Study Backs Decision to Move Forward With Pfizer Vaccine Candidate

Results of a phase 1 study of healthy adults receiving either of Pfizer and BioNTech’s 2 RNA-based vaccine candidates for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) supported the decision about which one to advance to later trials, researchers wrote Wednesday.

Writing in The New England Journal of Medicine, the authors said older adults had fewer systemic effects from BNT162b2 compared with BNT162b1. Pfizer has moved BNT162b2 into late-stage trials.

The study is part of Pfizer and BioNTech’s larger trial to find a vaccine to prevent SARS-CoV-2 from causing coronavirus disease 2019 (COVID-19). Previous studies conducted in Germany and the United States narrowed down the companies’ investigation to these 2 candidates.

Researchers have begun trial enrollment for a phase 2/3 international trial that will assess the safety and efficacy profile of BNT162b2 at the 30-μg dose level in up to 44,000 participants aged 18 to 85 years.

In the phase 1 study to evaluate safety and immunogenicity, a total of 195 healthy participants underwent a 4:1 randomization in 13 groups to either receive a placebo or vaccine candidate. Each group had 15 participants, where 12 would receive a vaccine candidate and 3 would receive a placebo.

Participants were aged 18 to 55 years and 65 to 85 years.

The ongoing, placebo-controlled, observer-blinded, dose-escalated phase 1 trial tested dosages of 10 μg, 20 μg, 30 μg, and 100 μg.

All of the groups received 2 doses administered 21 days apart, except for the group receiving 100 μg of BNT162b1, who only received 1 dose because patients who received the active vaccine experienced reactogenicity.

Severe systemic reactions, including fatigue, headache, chills, muscle pain, and joint pain, were reported in a small number of younger patients who received BNT162b2. However, none of the older recipients of BNT162b2 reported severe reactions.

The study’s results come days after pauses were announced for Johnson & Johnson’s and Eli Lilly’s vaccine trials. AztraZeneca’s vaccine trial was also temporarily halted in late September.

Amid the vaccine race, in response to being mentioned by the president during the first presidential debate, Pfizer’s CEO Albert Bourla released a statement earlier this month saying that the company will not succumb to political pressure or cut corners on development.

In September, a group of scientists and academics penned a letter to Bourla urging him to follow safety standards and wait until all participants in the phase 3 trial have received their second dose of the vaccine and that monitoring should occur through late November before filing for an Emergency Use Authorization.

Reference

Walsh, EE, French RW, Falsey AR, et al. Safety and immunogenicity of two RNA-based COVID-19 vaccine candidates. N Engl J Med. Published October 14 2020. doi:10.1056/NEJMoa2027906