A Timeline of COVID-19 Developments in 2020

Updated January 1, 2021

As the year ended, the United States surpassed 20 million infections from SARS-CoV-2, and more than 346,000 deaths. Globally, cases rose to 83,832,334 and 1,824,590 deaths.

Cases in some parts of the country began surging again in the weeks after Thanksgiving; the same effect may be seen in January as health officials are gravely concerned about the extent of travel for the Christmas and winter holidays. The Transportation Security Administration said it screened the most passengers (1.3 million) on the Sunday before Christmas, the most since March 15.

While vaccines began to roll out in the last month of the year, distribution challenges became evident and the United States fell short of its goal of providing an initial dose to 20 million people by December 31.

This is an updated look at how the pandemic progressed throughout 2020.

January 9 — WHO Announces Mysterious Coronavirus-Related Pneumonia in Wuhan, China

At this point, the World Health Organization (WHO) still has doubts about the roots of what would become the COVID-19 pandemic, noting that the spate of pneumonia-like cases in Wuhan could have stemmed from a new coronavirus. There are 59 cases so far, and travel precautions are already at the forefront of experts’ concerns.

January 20 — CDC Says 3 US Airports Will Begin Screening for Coronavirus

Three additional cases of what is now the 2019 novel coronavirus are reported in Thailand and Japan, causing the CDC to begin screenings at JFK International, San Francisco International, and Los Angeles International airports. These airports are picked because flights between Wuhan and the United States bring most passengers through them.

January 21 — CDC Confirms First US Coronavirus Case

A Washington state resident becomes the first person in the United States with a confirmed case of the 2019 novel coronavirus, having returned from Wuhan on January 15, thanks to overnight polymerase chain reaction testing. The CDC soon after deploys a team to help with the investigation, including potential use of contact tracing.

January 21 — Chinese Scientist Confirms COVID-19 Human Transmission

At this point, the 2019 novel coronavirus has killed 4 and infected more than 200 in China, before Zhong Nanshan, MD, finally confirms it can be transmitted from person to person. However, the WHO is still unsure of the necessity of declaring a public health emergency.

January 23 — Wuhan Now Under Quarantine

In just 2 days, 13 more people died and an additional 300 were sickened. China makes the unprecedented move not only to close off Wuhan and its population of 11 million, but to also place a restricted access protocol on Huanggang, 30 miles to the east, where residents can’t leave without special permission. This means up to 18 million people are under strict lockdown.

January 31 — WHO Issues Global Health Emergency

With a worldwide death toll of more than 200 and an exponential jump to more than 9800 cases, the WHO finally declares a public health emergency, for just the sixth time. Human-to-human transmission is quickly spreading and can now be found in the United States, Germany, Japan, Vietnam, and Taiwan.

February 2 — Global Air Travel Is Restricted

By 5 pm on Sunday, those en route to the United States have to have left China or they can face a 2-week home-based quarantine if they had been in Hubei province. Mainland visitors, however, will need to undergo health screenings upon their return, and foreign nationals can even be denied admittance. Other countries beginning to impose similar air-travel restrictions at this point include Australia, Germany, Italy, and New Zealand.

February 3 — US Declares Public Health Emergency

The Trump administration declares a public health emergency due to the coronavirus outbreak. The announcement comes 3 days after WHO declared a Global Health Emergency as more than 9800 cases of the virus and more than 200 deaths had been confirmed worldwide.

February 10 — China’s COVID-19 Deaths Exceed Those of SARS Crisis

The COVID-19 death toll surpasses that of the severe acute respiratory syndrome (SARS) outbreak from 17 years ago, totaling 908 reported deaths in China in the last month compared with 774 deaths in the SARS crisis.

February 25 — CDC Says COVID-19 Is Heading Toward Pandemic Status

Explaining what would signify a pandemic, Nancy Messonnier, MD, director of the CDC's National Center for Immunization and Respiratory Diseases, says that thus far COVID-19 meets 2 of the 3 required factors: illness resulting in death and sustained person-to-person spread. Worldwide spread is the third criteria not yet met at the time.

March 6 — 21 Passengers on California Cruise Ship Test Positive

Twenty-one people of just 46 tested aboard a cruise ship carrying more than 3500 people off the California coast test positive for COVID-19, with 19 being crew members. The ship is held at sea instead of being allowed to dock in San Francisco while testing is conducted. Since the event, 60 passengers have sued the cruise line and parent company, Carnival Corp, for gross negligence in how passenger safety was handled.

March 11 — WHO Declares COVID-19 a Pandemic

In declaring COVID-19 a pandemic, Tedros Adhanom Ghebreyesus, director general of WHO, said at a briefing in Geneva the agency is “deeply concerned by the alarming levels of spread and severity” of the outbreak. He also expressed concern about “the alarming levels of inaction.”

March 13 — Trump Declares COVID-19 a National Emergency

President Donald Trump declares the novel coronavirus a national emergency, which unlocks billions of dollars in federal funding to fight the disease’s spread.

March 13 — Travel Ban on Non-US Citizens Traveling From Europe Goes Into Effect

The Trump administration issues a travel ban on non-Americans who visited 26 European countries within 14 days of coming to the United States. People traveling from the United Kingdom and the Republic of Ireland are exempt.

March 17 — University of Minnesota Begins Testing Hydroxychloroquine

The University of Minnesota launches a clinical trial to investigate whether hydroxychloroquine can prevent an individual exposed to COVID-19 from becoming ill or reduce the severity of the infection. The trial is limited to those at high risk of exposure and aims to enroll 1500 individuals.

March 17 — CMS Temporarily Expands Use of Telehealth

CMS expands its telehealth rules, permitting use during the COVID-19 pandemic as a means to protect older patients from potential exposure. The relaxation allows Medicare to cover telehealth visits the same as it would regular in-person visits.

March 17 — Administration Asks Congress to Send Americans Direct Financial Relief

Trump asks Congress to expediate emergency relief checks to Americans as part of an economic stimulus package. The proposal comes just as the United States reports its 100th death from COVID-19.

March 19 — California Issues Statewide Stay-at-Home Order

California becomes the first state to issue a stay-at-home order, mandating all residents to stay at home except to go to an essential job or shop for essential needs. The order also instructs health care systems to prioritize services to those who are the sickest.

March 24 — With Clinical Trials on Hold, Innovation Stalls

Overwhelmed hospitals are keeping out everyone who does not need to be there, and that means delaying the start of new clinical trials, according to an interview. The Center for Biosimilars^® reported that drugs with fresh FDA approvals are not likely to launch, as their chances of making it into circulation are dim with hospitals struggling just to find enough personal protective equipment.

March 25 — Reports Find Extended Shutdowns Can Delay Second Wave

Mathematical models based on social distancing measures implemented in Wuhan, China, show keeping tighter measures in place for longer periods of time can flatten the COVID-19 curve.

March 26 — Senate Passes CARES Act

The Senate passes the Coronavirus Aid, Relief, and Economic Security (CARES) Act, providing $2 trillion in aid to hospitals, small businesses, and state and local governments, while including an elimination of the Medicare sequester from May 1 through December 31, 2020.

March 27 — Trump Signs CARES Act Into Law

The House of Representatives approves the CARES act, the largest economic recovery package in history, and Trump signs it into law. The bipartisan legislation provides direct payments to Americans and expansions in unemployment insurance.

March 30 — FDA Authorizes Use of Hydroxychloroquine

FDA issues an emergency use authorization (EUA) for “hydroxychloroquine sulfate and chloroquine phosphate products” to be donated to the Strategic National Stockpile and donated to hospitals to treat patients with COVID-19. The EUA would be rescinded June 15, except for patients in clinical trials, in the wake of reports of heart rhythm problems among some patients.

March 31 — COVID-19 Can Be Transmitted Through the Eye

A report in JAMA Ophthalmology creates a stir with the finding that patients can catch the virus that causes COVID-19 through the eye, despite low prevalence of the virus in tears. The coverage of the study involving 38 patients from Hubei Province, China, drew some of AJMC.com’s highest readership of 2020, as the findings contradicted assumptions by leading professional societies.

April 8 — Troubles With the COVID-19 Cocktail

“What do you have to lose?” Trump asks when touting the malaria drug hydroxychloroquine or the related chloroquine as possible treatments for COVID-19. With a common antibiotic, azithromycin, the drug cocktail becomes an early candidate to prevent hospitalization or death. But Trump’s promotion of the combination, despite known heart risks for some patients, prompts the American Heart Association, the American College of Cardiology, and the Heart Rhythm Society to warn in a joint guidance that the drugs are not for everyone.

April 16 — “Gating Criteria” Emerge as a Way to Reopen the Economy

After Trump briefly entertains the idea of reopening the US economy in time for Easter Sunday, the White House releases broad guidelines for how people could return to work, to church, and to restaurants and other venues. The plan outlines the concept of “gating criteria,” which call for states or metropolitan areas to achieve benchmarks in reducing COVID-19 cases or deaths before taking the next step toward reopening.

April 28 — Young, Poor Avoid Care for COVID-19 Symptoms

As the pandemic lingers, the term “deferred care” caught fire in health care circles—referring to the fact that many would avoid a doctor’s office or hospital for any procedure that could wait. But a Gallup poll finds a darker side to this phenomenon: 1 in 7 Americans report they would not seek care for a fever or dry cough—the classic symptoms of COVID-19. The reason? Cost concerns. Those most likely to avoid medical treatment for symptoms are younger than age 30 and make less than $40,000 a year. By the end of April, 26.5 million Americans have filed for unemployment since mid-March.

April 29 — NIH Trial Shows Early Promise for Remdesivir

National Institutes of Health (NIH) trial data, which are not peer reviewed, show that remdesivir, made by Gilead Sciences, is better than placebo in treating COVID-19. Patients with advanced COVID-19 and lung involvement who received the antiviral had a 31% faster recovery time, or about 4 days.

May 1 — Remdesivir Wins EUA

Shortly after the trial data are published, FDA grants an EUA to remdesivir after preliminary data from an NIH trial found the treatment accelerated recovery in individuals with advanced COVID-19 and lung involvement.

May 9 — Saliva-Based Diagnostic Test Allowed for At-Home Use

The FDA broadens authorization of a saliva-based test to detect COVID-19 infection; the EUA is granted to Rutgers Clinical Genomics Laboratory. The test makes it possible for those who cannot get to a collection center to get tested, including those who are home because they are ill, quarantined, or at high risk of infection due to their age or comorbidities.

May 12 — Death Toll Likely Underestimated, Fauci Testifies

Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, testifies before the US Senate that the US death toll of 80,000 is likely an underestimate. He warns against the relaxation of social distancing and says he is “cautiously optimistic” that a vaccine will be effective and achieved within 1 or 2 years.

May 21 — United States and AstraZeneca Form Vaccine Deal

The Trump administration and AstraZeneca announce a collaboration to speed development of a COVID-19 vaccine called AZD1222. HHS says it expects the first doses to be available as early as October 2020; phase 3 clinical studies are underway this summer.

May 28 — US COVID-19 Deaths Pass the 100,000 Mark

The CDC says surpassing 100,000 deaths is a “sobering development and a heart-breaking reminder of the horrible toll of this unprecedented pandemic.” It asks that Americans continue following local and state guidance on prevention strategies, such as social distancing, good hand hygiene, and wearing a face mask while in public.

June 4 — Lancet, NEJM Retract COVID-19 Studies on Hydroxychloroquine

On the same day, The New England Journal of Medicine and The Lancet both retract 2 studies on the use of hydroxychloroquine in COVID-19, after the authors said they could not vouch for the data used. A private database of medical records compiled by a little-known firm called Surgisphere was used in both studies. The retractions bring to light the difficulty of publishing vital COVID-19 research while ensuring accuracy.

June 10 — US COVID-19 Cases Reach 2 Million

The number of confirmed cases of COVID-19 hits 2 million in the United States as new infections continue to rise in 20 states. Cases begin to spike as states ease social distancing restrictions.

June 16 — HHS Announces COVID-19 Vaccine Doses Will Be Free for Some

Officials associated with the United States’ Operation Warp Speed, a project to rapidly develop and deploy a COVID-19 vaccine, explain that the vaccine would be provided for free to elderly patients and other vulnerable populations who cannot afford it.

June 18 — WHO Ends Study Into Hydroxychloroquine

WHO announces it will stop testing hydroxychloroquine as a treatment for COVID-19. The data from the Solidarity Trial show the drug did not reduce mortality. According to WHO, patients who were previously administered the drug would finish their course or stop based on a supervisor’s discretion.

June 20 — NIH Halts Trial of Hydroxychloroquine

Just days after WHO ended its own trial, the NIH announces it is halting a clinical trial examining the safety and effectiveness of hydroxychloroquine as a treatment for COVID-19. The study indicates that the treatment does no harm, but also provides no benefit.

June 22 — Study Suggests 80% of Cases in March Went Undetected

A study in Science Translation Medicine suggests that as many as 80% of Americans who sought care for flu-like illnesses in March were actually infected with the virus that causes COVID-19. According to the research, if one-third of these patients sought COVID-19 testing, it may have amounted to 8.7 million infections.

June 26 — White House Coronavirus Task Force Addresses Rising Cases in the South

For the first time in 2 months, the White House Coronavirus Task Force holds a briefing. The focus of the discussion is the rising number of cases and growing positive test rate in some states. As cases rise, Texas and Florida both decide to halt the reopenings as each state records growing numbers of cases.

June 29 — Gilead Sets Price for Remdesivir at $3120

Gilead Sciences sets a price for remdesivir, which can shorten hospitalization stays for patients with COVID-19, at $520 a vial. With a treatment course of 6 vials, the typical treatment course will be $3120 per patient for people covered with private insurance. Critics of the price point are quick to point out that taxpayers funded the COVID-19 remdesivir trial through the National Institute of Allergy and Infectious Diseases.

June 30 — Fauci Warns New COVID-19 Cases Could Hit 100,000 a Day

In his appearance before the Senate Health, Education, Labor, and Pensions Committee, Fauci warns that while the current daily number of new cases in the United States is hovering around 40,000, that could reach as high as 100,000 new cases per day given the outbreak’s current trajectory.

July 2 — States Reverse Reopening Plans

Several states, including California and Indiana, postpone or reverse plans to reopen their economies, as the United States records 50,000 new cases of COVID-19—the largest one-day spike since the pandemic’s onset. New Mexico also extends the state’s emergency public health order through July 15 and implements a $100 fine for those not adhering to required mask usage.

July 6 — Scientists, Citing Airborne Transmission, Ask WHO to Revise Guidance

Hundreds of scientists call on the WHO to revise recommendations on COVID-19 to better reflect its potential for airborne transmission. Previously, the organization stated that COVID-19 spreads primarily via small droplets from the nose or mouth emitted when an infected individual coughs, sneezes, or speaks.

July 7 — CMS Plans to Pay More for Home Dialysis Equipment

CMS proposes a rule aimed at keeping patients outside of dialysis centers for treatment as the nation faces rising cases. The transitional add-on payment for new and innovative equipment or supplies would allow greater access to home dialysis machines, improving accessibility for Medicare beneficiaries.

July 7 — US Surpasses 3 Million Infections, Begins WHO Withdrawal

The same day that the United States reports 3 million COVID-19 infections, the nation begins its withdrawal from WHO, citing its response to the global pandemic. The Trump administration notifies the United Nations of its decision, which would not take effect until 2021 and could be reversed by President-elect Joe Biden.

July 9 — WHO Announces COVID-19 Can Be Airborne

WHO announces that the novel coronavirus can be transmitted through the air after more than 200 scientists sign a letter urging the agency to revise its recommendations. In an updated scientific brief, WHO notes that the virus may linger in the air in crowded indoor spaces and emphasizes that the virus may be spread by asymptomatic individuals.

July 14 — States With COVID-19 Spikes Report Greatest Health Insurance Coverage Losses

As of May 2020, states with the greatest percentage of nonelderly adults who are currently uninsured included Florida, Texas, Oklahoma, Mississippi, North Carolina, South Carolina, and Georgia, according to an analysis from Families USA. These states also report the highest numbers of new COVID-19 cases per 100,000 residents as of July 12.

July 14 — Early Moderna Data Point to Vaccine Candidate’s Efficacy

Data from phase 1/2 trials of Moderna Inc’s COVID-19 vaccine show that doses produced immune responses in all 3 groups of 15 volunteers. The company was the first to enter large-scale human trials. Adverse effects of the vaccine candidate, which is administered twice 28 days apart, include injection site pain and chills.

July 15 — New Hospital Data Reporting Protocol Prompts Concern

An announcement mandates that all hospitals must bypass the CDC and send COVID-19–related information to a central database run by HHS Protect. Previously, data were sent to the CDC’s National Healthcare Safety Network site. Following the change, questions are raised regarding the future of COVID-19 data transparency and politicization.

July 16 — US Reports New Record of Daily COVID-19 Cases

The United States reported a record 75,600 cases of COVID-19 in a single day, breaking a record set the week prior. At this point, daily cases have seen 11 record totals in the past month alone. Texas, Hawaii, and Montana are among the 10 states reporting new record daily totals.

July 20 — Diagnostic Delays From COVID-19 May Increase Cancer-Related Deaths

The next several years could bear witness to thousands of additional deaths from cancer that could have been prevented through routine diagnostic care that was delayed because of the COVID-19 pandemic. Notably, delays in referrals and screenings for breast, colorectal, esophageal, and lung cancers were indicated in a pair of studies published in The Lancet Oncology to potentially lead to almost 10% (n = 3291-3621) more deaths in England over the next 5 years.

July 21 — Vaccines From AstraZeneca, CanSino Biologics Show Promising Results

Two experimental vaccines, one from AstraZeneca and the other from CanSino Biologics, show promising results against COVID-19. The interim results of AstraZeneca’s phase 1/2 COV001 trial of AZD1222 show that the vaccine was tolerated and generated robust immune responses against the virus in all participants who were evaluated. In the CanSino Phase 2 trial, the vaccine induced significant neutralizing antibody responses, with as many as 95% of patients showing either cellular or humoral immune responses at day 28 post vaccination.

July 22 — HHS, DOD Announce Vaccine Distribution Agreement With Pfizer and BioNTech

HHS and the Department of Defense (DOD) strike a partnership with biotech giants Pfizer and BioNTech for a December delivery of 100 million doses of their COVID-19 vaccine candidate, BNT162, in a deal that could expand to 600 million doses if the vaccine receives approval or an EUA from the FDA, and even then only if phase 3 clinical trial results confirm that the vaccine is safe and effective.

July 23 — Antibody Levels Drop After First 3 Months of COVID-19 Infection

Findings from a research letter published in the New England Journal of Medicine indicate that levels of antibodies against SARS-CoV-2, the virus that causes COVID-19, dropped dramatically across the first 3 months of infection. At this rate, researchers note that antibody resistance would be depleted within a year, although experts note that the possibility of being infected again with the virus is very unlikely.

July 23 — Antibody Cocktail May Treat, Prevent COVID-19

Researchers conceive of an antibody cocktail that uses antibodies directed at different locations on the familiar “spike” on SARS-CoV-2 that gives the virus its “corona.” The scientists found the antibodies fell into 2 distinct groups, targeting different regions of the viral spike. Thus, they say, the battle against COVID-19 could be waged on separate fronts, much like those against HIV and some forms of cancer.

July 27 — Moderna Vaccine Begins Phase 3 Trial, Receives $472M From Trump Administration

In beginning the first phase 3 clinical trial to examine a vaccine candidate against COVID-19, Moderna announces that the Trump administration increased funding by $472 million to expand the trial to 30,000 US participants. The move now brings the total investment made by the Biomedical Advanced Research and Development Authority to $955 million.

July 27 — Senate Introduces HEALS Act

Republicans introduce a package of bills known together as the Health, Economic Assistance, Liability Protection, and Schools (HEALS) Act, which provides provisions for another stimulus check, more money for small businesses, and liability protections for companies seeking to bring employees back to the workplace during the pandemic.

July 29 — FDA Grants Truvian EUA for Rapid Antibody Test

FDA grants Truvian Sciences an EUA for its Easy Check COVID-19 IgM/IgG antibody test after it was shown to exceed EUA requirements, including a sensitivity rate of 98.44% and a specificity of 98.9%. The announcement follows the FDA’s increased oversight of antibody tests on May 5, requiring them to meet standards of other molecular tests.

August 3 — New US Pandemic Phase; US to Pay Sanofi, GlaxoSmithKline $2B for Vaccine

Coronavirus response coordinator Deborah Birx, MD, says the United States has entered a new phase of the pandemic, as widespread cases nationwide differ from early concentrated outbreaks first reported in March and April. Birx’s comments come as the United States agrees to a $2.1 billion deal with GlaxoSmithKline and Sanofi Pasteur in an effort to develop, manufacture, and scale up delivery of a COVID-19 vaccine.

August 4 — Rural Hotspots Face Lack of Intensive Care Unit Beds

Almost 5 months after the pandemic was declared a national emergency in the United States, 49% of low-income areas have no free beds in their intensive care units vs 3% of the wealthiest. Hospitals are now being forced to transfer their sickest patients to care facilities in these wealthier areas, with the Southwest and West facing an especially difficult bed shortage.

August 7 — Talks Stall on Second Relief Package

Stimulus checks from the first package rolled out seemingly quickly, but talks stall between the White House and Democrats on a potential subsequent round of relief, even as jobless claims reach a record high of 1.186 million. Trump continues to claim he will issue executive orders if a deal cannot be reached.

August 11 — Trump Administration Reaches Deal With Moderna

Despite still waiting on final data, the Trump administration reportedly agrees to pay $1.5 billion to Moderna for 100 million doses of its vaccine candidate, mRNA-1273, or an average per-dose price of $15. The vaccine, however, is still under investigation in the joint phase 3 COVE trial Moderna is conducting with the National Institute of Allergy and Infectious Diseases and the Biomedical Advanced Research and Development Authority.

August 12 — Severe Obesity Increases Mortality Risk From COVID-19

Investigators from Kaiser Permanente publish their findings showing that patients with a body mass index (BMI) of 40 to 44 kg/m² have a risk of death from COVID-19 that is more than twice that of individuals whose BMI is 18.5 to 24 mg/m². An abundance of comprehensive patient data enabled the team to isolate obesity’s effects compared with those resulting from more than 20 comorbidities, health care use, and population density, among others. At the heart of this finding is that excess fat exacerbates the breathing issues brought on by COVID-19.

August 13 — Biden Calls for 3-Month Mask Mandate

Still a presidential nominee, Joe Biden calls on all governors to require their citizens to wear masks anytime they go out in public through November, and he claims he will mandate the practice if elected. At this point, there are a reported 165,000 deaths from COVID-19, and the measure is estimated to save 40,000 lives in the coming months. At this point, mask mandates still vary greatly among the states and regions.

August 15 — FDA Approves Saliva Test

The federal agency issues an EUA for SalivaDirect, a test developed by researchers at the Yale School of Public Health that is less invasive compared with the current standard nasal swabs. With shorter wait times not affecting test sensitivity, labs can reportedly run 90 test samples, which are collected in sterile containers, in under 3 hours. The test is also inexpensive and produces results similar to nasal swabbing.

August 17 — COVID-19 Now the Third-Leading Cause of Death in the US

In just 4 days, there’s been a 3.2% uptick in COVID-19–related deaths, to 170,434, giving the disease a No. 3 ranking behind heart disease in the top spot and cancer at No. 2. Deaths now exceed 1000 per day and nationwide cases exceed 5.4 million. Testing has dropped off by an average 68,000 per day, despite death being 8 times more likely in the United States vs in Europe.

August 23 — Convalescent Plasma Is Cleared for Use by FDA

The FDA issues another EUA, this time for convalescent plasma from recovered patients as a therapy to fight COVID-19. There is ongoing debate about the treatment, which is rooted in experts’ skepticism that all patient populations will derive benefit from it, due to a lack of efficacy data. Meanwhile, White House Press Secretary Kayleigh McEnany claims it is a therapeutic breakthrough.

August 24 — Remdesivir’s Clinical Benefits Questioned

A global, multicenter study finds that the antiviral drug remdesivir had little effect on patients hospitalized with COVID-19. The findings, published in JAMA, indicate there were no significant differences in duration of supplemental oxygen or hospitalization between the intervention group given remdesivir and the control group given standard care.

August 25 — CDC Changes Testing Guidance, but Later Reverses Itself

The CDC quietly changes its guidance on who should get tested for COVID-19, saying that individuals who are asymptomatic, but have been exposed, do not need testing. After it is revealed the decision had bypassed CDC’s usual scientific review process and without internal review, the changes are reversed.

August 26 — FDA Grants EUA to Abbott’s Rapid Test

A portable rapid COVID-19 test that can deliver results in under 15 minutes was cleared by the FDA under an EUA. The test is aimed at places like workplaces and schools.

August 28 — First Known Case of COVID-19 Reinfection Reported in the US

A 25-year-old man from Nevada became reinfected with COVID-19 in late May after recovering from a mild case in April, reports say. It marks the first reported case of reinfection in the United States; the second occurrence resulted in a much more severe case, requiring hospitalization and oxygen. A full study of the case is published in Lancet Infectious Disease Journal in October.

September 1 — US Rejects WHO Global COVID-19 Vaccine Effort

The United States says it will not participate in an initiative by the WHO to develop, make, and distribute a COVID-19 vaccine. COVAX, with 172 countries participating, was launched so that an eventual vaccine could be distributed evenly to poor and developing countries.

September 3 — Steroids Reduce Mortality in Severe Cases; Sanofi, GSK Begin Human Vaccine Trials

Three studies report that inexpensive steroids are the most effective treatment to date for serious COVID-19. Results from the studies find that the use of systemic corticosteroids can reduce the risk of death by one-third in individuals hospitalized with COVID-19 compared with usual care or placebo.

Additionally, Sanofi and GlaxoSmithKline (GSK) start a clinical trial of their protein-based vaccine; the COVID-19 vaccine uses the same protein-based technology as one of Sanofi’s influenza vaccines and is combined with an adjuvant, or booster, developed by GSK.

September 3 — Bioethicists Weigh In on Equitable Vaccine Distribution

Nineteen bioethicists outline measures for equitable distribution of limited supplies of any COVID-19 vaccine; the plan, called the Fair Priority Model, considers 3 types of harms caused by COVID-19 and 3 values that must be adhered to when considering the allocation of a scarce supply of vaccine.

September 8 — AstraZeneca Halts Phase 3 Vaccine Trial

The phase 3 trial for AstraZeneca’s potential COVID-19 vaccine is halted for a safety data review following an unknown adverse reaction in a patient. The patient was part of the United Kingdom arm of the trial. At the time, the nature of the adverse reaction was not known, but the company did say that the participant was expected to recover. AstraZeneca says the hold was initiated as “a routine action.”

September 14 — US Airports Stop Screening International Travelers

The government announces it will stop screenings taking place at some airports since January. In March, incoming flights from high-risk countries, including China, Iran, and much of Europe, were funneled through 15 designated airports, but as of September 14, the flights will no longer be redirected and all passenger screenings will be halted. As part of the screening process, passengers had their temperatures taken and were subject to a basic health screening about typical COVID-19 symptoms before they could go through passport control and customs.

September 14 — Pfizer, BioNTech Expand Phase 3 Trial

After initially aiming to recruit 30,000 participants, Pfizer and BioNTech announce they will expand the phase 3 trial of their COVID-19 vaccine by 50% to 44,000. The goal of expanding the trial is to increase data on safety and efficacy and promote a more diverse population, including adolescents as young as 16 years and patients with HIV, hepatitis C, or hepatitis B. The Pfizer/BioNTech vaccine is provided as 2 shots given 3 weeks apart, but the vaccine must be kept at a temperature of –70 degrees Celsius (–94 degrees Fahrenheit), which may make distribution a challenge.

September 14 — NIH Launches Investigation Into Halted Astrazeneca Trial

After AstraZeneca put its phase 3 trial on hold, the NIH announces it is launching an investigation into the adverse reaction before the FDA decides whether or not to resume the trial. The participant suffered spinal cord damage, and there remained some uncertainty about what happened to cause the damage.

September 15 — CDC Reports on Spread of COVID-19 at Restaurants

A study published in Morbidity and Mortality Weekly Report finds that people who recently tested positive for COVID-19 were 2.4 times more likely to have dined out. The study considered restaurant dining to include being seated at a patio, being seated outdoors, and being seated indoors. The odds jumped almost 4-fold for participants who had been to a bar or café. The majority of participants (71%) claimed to have worn masks in the 2 weeks before their diagnosis.

September 16 — Trump Administration Releases Vaccine Distribution Plan

A plan devised by HHS and the DOD aims to make a COVID-19 vaccine free for all Americans, with the vaccine being rolled out in January 2021. Once a vaccine is authorized, the plan dictates that 6.6 million kits of supplies needed to administer vaccines will also be distributed. The plan does not include a decision on who would be the first to receive the vaccine.

September 17 — Europe Reports Rising COVID-19 Cases

Europe reports a sharp increase in COVID-19 cases, with numbers growing at a higher rate than they did during the previous peak in March. In the first half of September, more than half of all European countries reported an increase greater than 10%.

September 21 — CDC Pulls Guidance Saying COVID-19 Transmission Is Airborne

The CDC removes guidance from its website that had been posted 3 days earlier saying that the transmission of COVID-19 is airborne. CDC says the document was posted in error and the guidance was a “draft version of proposed changes.”

September 21 — Johnson & Johnson Begins Phase 3 Vaccine Trial

Johnson & Johnson announces that it began a large phase 3 clinical trial of its COVID-19 vaccine candidate. This vaccine does not need to be frozen and may require 1 administration instead of 2. The trial is expected to test the vaccine in 60,000 participants, making it the largest phase 3 trial of all vaccines currently being tested.

September 23 — A New, More Contagious Strain of COVID-19 Is Discovered

A study conducted at Houston Methodist Hospital finds a more contagious strain of COVID-19 in a large portion of recent patient samples. Investigators analyzed samples from the earliest phase of the pandemic and a more recent infection wave, finding that nearly all strains from the more recent phase had a mutation that allows the virus to bind and infect more cells.

September 25 — Midwest States See Increase in COVID-19 Cases

Over the course of September, Midwest states experience a dramatic rise in COVID-19 cases, with South Dakota alone having a 166% increase and 10 other states reporting record 1-day increases. The annual Sturgis motorcycle rally, school and university reopenings, and Labor Day weekend celebrations have all been cited as case links.

September 28 — Global COVID-19 Deaths Surpass 1 Million

The number of deaths linked to COVID-19 worldwide crosses the 1 million mark, according to The New York Times, surpassing the deaths caused by HIV, dysentery, malaria, influenza, cholera, and measles combined in 2020.

September 29 — HHS to Distribute 100 Million Rapid Tests to States

HHS announces a plan to send 100 million rapid COVID-19 tests, developed by Abbott, to states by the end of the year. The rapid tests are cheaper and faster than laboratory tests and can return results in about 15 minutes. The plan was designed to assist K-12 schools in reopening.

September 29 — Regeneron Announces Positive Results for Monoclonal Antibody Treatment

Regeneron releases study results from its ongoing phase 1/2/3 trial showing that its proposed monoclonal antibody treatment for COVID-19, REGN-COV2, was linked to quicker recovery, reduced viral load, and the need for fewer medical visits. REGN-COV2 is a mixture of 2 monoclonal antibodies (REGN10933 and REGN 10987).

October 2 — Trump, First Lady Test Positive for COVID-19; Trump Enters Hospital

President Trump announces that he and First Lady Melania Trump have tested positive for COVID-19. After experiencing mild symptoms of the disease, Trump was taken to Walter Reed National Military Medical Center, “out of an abundance of caution,” said Press Secretary Kayleigh McEnany in a statement.

October 5 — Trump Leaves Hospital, Continues Receiving Treatment

After 3 days, Trump is discharged from the hospital and transported back to the White House, where he would continue to receive treatment for COVID-19 and be monitored. White House physician Sean Conley, DO, says that the president’s fever is gone and that his oxygen levels are normal. During his time at the hospital, Trump’s treatment consisted of Regeneron’s investigational antibody cocktail, remdesivir, and dexamethasone.

October 8 — NEJM Criticizes Trump’s COVID-19 Response; 39 States See Case Spikes

In an editorial published by the New England Journal of Medicine (NEJM), 34 editors call out the Trump administration’s response of the COVID-19 pandemic, stating that leaders have “taken a crisis and turned it into a tragedy.”

Additionally, 39 states report seeing a rise in COVID-19 cases. Nine states set 7-day records for infections, and Wisconsin and Hawaii report a record number for deaths in a 7-day period.

October 8 — More Americans Trust Biden to Lead Health Care System

A poll released on this date by Gallup-West Health, but taken before Trump’s COVID-19 diagnosis, finds that more Americans trust Biden to lead the US health care system through the pandemic. The poll notes that Biden had the support of 52% of voters on this issue, compared with 39% who supported Trump, with the remaining undecided. The results leave room for Trump to narrow Biden’s wide lead in the national polls.

October 8 — White House COVID-19 Outbreak Grows to 34

By this date, the cluster of people infected by the COVID-19 outbreak connected to the Rose Garden ceremony for Supreme Court Justice Amy Coney Barrett has grown to 34, including several White House staff members, according to The Washington Post. CDC experts offer assistance with contact tracing.

October 9 — US Signs Deal With AstraZeneca

The Trump administration signed a $486 million agreement with AstraZeneca to develop an antibody treatment for COVID-19, which would call for HHS and the DOD to work with the company to roll out late-stage development and large-scale manufacturing of AZD7442, a cocktail of 2 monoclonal antibodies with potential to treat or prevent the disease.

October 12 — Johnson & Johnson Halts Vaccine Trial

Johnson & Johnson halts recruitment for its phase 3 ENSEMBLE trial for its COVID-19 vaccine halts vaccine trial over a patient’s unexplained illness, a development first reported in POLITICO. The company reports at the time that adverse events that temporarily pause recruitment are not uncommon and mean that clinical trials are being conducted in a safe manner. It later resumes the study of its 1-dose regimen, which is unique among the leading vaccine candidates. The company has also launched ENSEMBLE 2 to study a 2-dose version of the vaccine.

October 15 — US Cases Spike Again; Studies Connect Blood Type and COVID-19 Risk

The United States reports 60,000 new COVID-19 cases, a number not reached since early August. Cases rise countrywide, and 44 states report caseloads surpassing those seen in mid-September. More rural states see numbers even higher than during first waves in the spring.

A pair of studies in Blood Advance suggest that the risk of becoming infected with COVID-19 or developing life-threatening complications from the virus might be related to blood type. Researchers caution that the results do not point to any blood type being completely protective or vulnerable to the virus.

October 19 — Global Cases Top 40 Million

Data from Johns Hopkins University indicate that COVID-19 cases have topped 40 million worldwide as the United States and other countries see their highest rates of new cases in months. More than 1.1 million people have been killed by the virus worldwide so far, and nearly 220,000 of those deaths were in the United States, which remains the hardest-hit country in the world.

October 22 — FDA Approves Remdesivir as First COVID-19 Drug

Gilead’s remdesivir is the first FDA-approved drug to treat COVID-19 after 3 randomized trials found it to decrease the length of hospital stays and reduce the likelihood that patients will require oxygen. None of the trials showed reduced risk of mortality, however, and a WHO-backed study found that the drug had “little to no effect” on hospitalized patients. The FDA does not mention the WHO trial in its risk-benefit assessment of remdesivir, stating that an NIH-backed trial supporting the approval was better suited to assess time to recovery than the WHO-backed trial.

October 23 — AstraZeneca and Johnson & Johnson Announce Restart of COVID-19 Vaccine Trials

AstraZeneca and Johnson & Johnson announce plans to restart clinical trials for their respective COVID-19 vaccine candidates after they both stopped due to safety concerns. Johnson & Johnson’s stalled on October 11, and a patient in the AstraZeneca trial developed neurological symptoms before its study was halted on September 6. An independent monitoring committee determined that the trial for the latter vaccine candidate was safe to continue.

October 28 — CMS Issues Vaccine, Treatment Coverage Rules

CMS provides new rules for insurance coverage, increasing what Medicare pays hospitals for COVID-19 treatments. Trump and Congress had enacted legislation calling for COVID-19 vaccines to be free, but new rules were necessary to fit that policy into the various payment requirements for public and private insurance. The new rules waive co-pays or deductibles on vaccines for seniors with Medicare.

November 4 — US Reports Unprecedented 100,000 Cases in 1 Day

The US hits a grim milestone with 100,000 new COVID-19 cases reported in a single day for the first time. The unprecedented spike in cases leads to a shortage of N95 face masks at health care facilities despite increased production, and workers continue to ration and reuse masks with no end in sight.

November 5 — Study Predicts Difficulties in Nationwide COVID-19 Immunity

An analysis of flu vaccination rates during the 2019-2020 flu season suggests that the path to vaccinating the majority of the country for SARS-CoV-2, thus achieving sufficient immunity, will not be an easy one. Just 52% of the US population received a flu vaccine in the time frame of the analysis, and the study also highlighted disparities: Lower vaccination rates were recorded in Black and Hispanic adults than White adults, and elderly adults were more likely to receive a vaccine.

November 9 — President-Elect Biden Announces COVID-19 Transition Team; Pfizer Publishes Vaccine Results

After former Vice President Joe Biden is determined to be the president-elect on November 7, he announces the names of the scientific, medical, and public health professionals who will serve on his Transition COVID-19 Advisory Board. The same day, Pfizer releases data from its COVID-19 vaccine trial showing that the vaccination was 90% effective.

November 9 — FDA Issues EUA for Eli Lilly’s Antibody Treatment

The FDA issues an EUA for Eli Lilly’s bamlanivimab, a monoclonal antibody treatment that mimics the immune system’s response to infection with SARS-CoV-2 and appears to protect high-risk patients with COVID-19 from progressing to more severe forms of the disease. Clinical trials showed reductions in COVID-19–related hospitalizations or emergency visits in these patients within 28 days of treatment compared with placebo.

November 11 — Indoor Venues Responsible for Much of COVID-19’s Spread

A new study in Nature observes that most new cases of COVID-19 originated from indoor gatherings in places like restaurants, gyms, and grocery stores, according to analysis of cell phone mobility data from large cities. The authors suggest that low-income neighborhoods have higher new case burdens because their public venues are more crowded and residents are more likely to work outside their homes.

November 16 ­— Moderna Reveals Vaccine Efficacy Results

The positive vaccine news continues with Moderna’s announcement that its experimental vaccine reduces the risk of COVID-19 infection by 94.5% in participants who received it. Like Pfizer’s vaccine, the Moderna vaccine works using mRNA, an innovative approach that has not yet been used in approved vaccines against any disease.

November 16 — FDA to Move Rapidly on EUAs for Pfizer, Moderna Vaccines

On CNBC’s “Squawk Box,” HHS Secretary Alex Azar says the FDA will move “as quickly as possible” to clear Pfizer’s and Moderna’s vaccine candidates for emergency use as long as the data support authorization. Both authorization applications are currently being completed, but Azar says that the FDA’s teams are working with both companies to “remove any unnecessary bureaucratic barriers.”

November 17 — Fauci Highlights the Need for Long-term Follow-up of COVID-19 Effects

During a talk at the American Heart Association Scientific Sessions, Fauci discusses the cardiovascular implications of COVID-19 and highlights the need to follow up with patients to better understand the long-term effects of infection. He points to symptoms like profound fatigue, shortness of breath, muscle aches, sporadic fevers, and an inability to concentrate, which up to one-third of patients live with for weeks or months after contracting COVID-19.

November 18 — Pfizer, BioNTech Vaccine Is 95% Effective

The results of a nearly 44,000-person trial demonstrate that the COVID-19 vaccine from Pfizer and BioNTech is 95% effective, making it as effective as vaccines for shingles and measles. Pfizer also announces that it will seek FDA approval within days so that distribution of the vaccine can happen by the end of the year.

November 20 — Pfizer, BioNTech Submit EUA Application; CDC Warns Against Holiday Travel

Pfizer and BioNTech submit their COVID-19 vaccine to the FDA for an EUA, making them the first companies to seek such an approval in the United States. The EUA submission includes safety data on about 100 children between the ages of 12 and 15 years.

At the same time, the CDC urges Americans to stay home for Thanksgiving amid national spikes in COVID-19 cases and hospitalizations. The agency recommends that people avoid mingling with people who have not resided in their household for the last 14 days. As cases in the United States surpass 11 million, CDC officials worry that the situation could worsen during the holiday season.

November 23 — AstraZeneca Reports Vaccine Is 90% Effective; FDA Grants EUA for Second Antibody Treatment

When AstraZeneca’s COVID-19 vaccine is administered as a half dose followed by a full dose at least a month later, it can be approximately 90% effective. This vaccine is easier to distribute and scale up than other vaccines, and the drug maker says it can have as many as 200 million doses by the end of 2020 and 700 million by the end of the first quarter of 2021.

Meanwhile, the FDA grants an EUA for a second COVID-19 antibody treatment. The cocktail, manufactured by Regeneron, was administered to Trump when he was battling COVID-19 at the beginning of October. In a clinical trial of 800 people, the treatment significantly reduced virus levels within days.

December 10 — FDA Advisory Panel Recommends Pfizer, BioNTech COVID-19 Vaccine

An FDA advisory panel endorses the first COVID-19 vaccine. The application for the Pfizer and BioNTech’s vaccine is heard in a public, day-long meeting; voting 17-4, with 1 abstention, the Vaccines and Related Biological Products Advisory Committee (VRBPAC) decides the benefits of the vaccine outweigh the risks for those 16 and older.

December 11 — FDA Agrees to EUA for COVID-19 Vaccine From Pfizer, BioNTech

A day after the panel votes, the FDA agrees to an EUA for the Pfizer, BioNTech vaccine, allowing shipments to begin; vaccinations of health care workers begin within days.

December 17 — FDA Panel Backs Moderna COVID-19 Vaccine

A week after hearing the application for the country’s first COVID-19 vaccine, the same FDA advisory panel meets and agrees that a second vaccine, from Moderna, will benefit individuals 18 years and older. The vote is 20-0, with 1 abstention. The Moderna vaccine is given 28 days apart; the Pfizer-BioNtech one, 21 days apart.

December 18 — FDA Signs Off on EUA for Moderna's COVID-19 Vaccine

The FDA issues the second EUA allowing shipments of the Moderna COVID-19 vaccine to begin.

December 21 — New COVID-19 Variant Circling the UK

The UK announces that a new strain of the virus that causes COVID-19, B.1.1.7, is spreading across the country. The novel variant is more contagious, but does not appear to be more lethal or lead to more severe disease.

December 23 — US Buys More Pfizer Vaccine

The Trump administration announces it will buy an additional 100 million doses of Pfizer and BioNTech’s vaccine.

December 28 — Novavax Starts Phase 3 Trial of COVID-19 Vaccine

Novavax begins a phase 3 clinical trial, PREVENT-19, for its investigational COVID-19 vaccine, NVX-CoV2373, in 30,000 volunteers in Mexico and the United States.

December 29 — First US Case of New COVID-19 Variant Found in Colorado

The recently discovered novel variant found a week prior in the United Kingdom is detected in a Colorado man in his 20s with no travel history. Scientists say they are concerned, but not surprised, since viruses are known to mutate.

December 30 — UK Approves Emergency Authorization for the AstraZeneca and Oxford COVID-19 Vaccine

As UK cases surge, regulators clear a vaccine from AstraZeneca and Oxford, AZD1222, for individuals 18 years and older.

December 31 —US Falls Short of Goal to Give 20 Million Vaccinations by Year End

As the year closed, the CDC says about 2.8 million people so far have received an initial vaccination. The US says on December 30 that about 14 million doses have been distributed, out of total of 20 million allocated doses.