St. Jude Study Questions Efficacy of the Flu Vaccine in Children With Leukemia

A retrospective study, published in the Journal of Pediatrics, has found that young patients with leukemia who have been vaccinated against the influenza virus are as susceptible to develop flu as their unvaccinated peers. These findings highlight the need to develop additional protective measures for this more at-risk population.

According to the CDC, children, especially those under 5 years, are at a higher risk of flu-related complications and should be vaccinated. Flu-related complications have led to between 7000 and 26,000 hospitalizations among this younger population since 2010 in the United States, and children with cancer, who have a weakened immune system due to their treatment, have been listed by the CDC as being at a higher-risk of flu-related complications.

Using data accumulated over 3 successive flu seasons—2011 to 2012, 2012 to 2013, and 2013 to 2014—researchers in the current study evaluated the rate of flu infection in 498 patients at St. Jude Children’s Research Hospital who were receiving treatment for acute leukemia. Of the 354 patients who had received a flu shot, 98 had been administered a booster dose. The patients had received the trivalent influenza vaccine, designed to afford protection against 3 strains of the virus based on their prevalence in a particular season. It is important to note that the flu vaccines in this study were considered a fairly good match for the circulating seasonal viruses.

The study found that despite receiving flu shots, the rate of flu and flu-like illness was similar between the vaccinated and the 144 unvaccinated patients who were evaluated.

According to the study’s senior author Elisabeth Adderson, MD, associate member of the St. Jude Department of Infectious Diseases, the evidence is preliminary. “The annual flu shot, whose side effects are generally mild and short-lived, is still recommended for patients with acute leukemia who are being treated for their disease,” Adderson said in a statement. “However, the results do highlight the need for additional research in this area and for us to redouble our efforts to protect our patients through other means.”

Adderson recommends several preventive strategies in this pediatric population whose immune system is extra susceptible due to their cancer treatment:

• Maintain good personal hygiene
• Avoid crowded places during the flu season
• "Cocooning,” which ensures everyone who comes in close contact with patients—family members, healthcare providers, and others—are vaccinated.