Flu Vaccine for All: A Critical Look at the Evidence

Eric A. Biondi, MD, MS; C. Andrew Aligne, MD, MPH


December 21, 2015


Does the evidence support the call for universal influenza vaccination?

Response from Eric A. Biondi, MD, MS
Assistant Professor of Pediatrics, Pediatric Hospitalist, University of Rochester Medical Center, Rochester, New York
Response from C. Andrew Aligne, MD, MPH
Assistant Professor of Pediatrics, Director of The Hoekelman Center, University of Rochester School of Medicine & Dentistry, Rochester, New York

Influenza vaccination is a yearly ritual. The Advisory Committee on Immunization Practices (ACIP)[1] and the American Academy of Pediatrics (AAP)[2] recommend annual influenza vaccination for all healthy persons 6 months of age or older who are without contraindications.

In an interview published in The Atlantic,[3] Tom Jefferson, head of the Vaccine Field Group at the Cochrane Database Collaboration (the world's leading producer of evidence-based medical reviews), voiced serious reservations about the data supporting influenza vaccine recommendations, stating that "The vast majority of the studies [are] deeply flawed. Rubbish is not a scientific term, but I think it's the term that applies."

A critical look at the evidence raises further questions about the flu shot recommendations. A 2012 Cochrane review[4] examining the efficacy of pediatric influenza vaccination noted that:

...industry-funded studies were published in more prestigious journals and cited more than other studies, independent of methodological quality and size. Studies funded from public sources were significantly less likely to report conclusions favorable to [influenza] vaccines... reliable evidence on influenza vaccines is thin but there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies.

And a 2014 Cochrane review[5] examining use of flu vaccine in healthy adults, including pregnant women, concluded that:

[Influenza] vaccination shows no appreciable effect on working days lost or hospitalization.

How Did We Get Here? The History of Influenza Vaccines

If the data supporting widespread influenza vaccination are weak, then why do such organizations as the AAP, ACIP, and the US Centers for Disease Control and Prevention (CDC) support a widespread influenza vaccination policy? As is so often the case, to understand the present, we must examine the past.

The 1918-1919 influenza pandemic, which occurred concurrently with World War I, killed approximately 50 million people around the world.[6] Despite little understanding of the etiology of the pandemic, physicians began administering various vaccines to soldiers in an attempt to stop the spread of the disease.

During World War II, the US Army, eager to prevent a recurrence of 1918, supported influenza vaccine development efforts by such scientists as Jonas Salk.[7] This early flu vaccine was studied in the military in 1944 and found to decrease episodes of illness with a temperature above 99°F[8]—a promising result, but not evidence of an impact on serious clinical outcomes. A subsequent evaluation in 1947 found that "the incidence of disease was no different in vaccinated and unvaccinated individuals."[9]

In other words, by the late 1940s a vaccine for influenza had been developed, but there was no evidence that it prevented serious outcomes. Nevertheless, the vaccine was released for use in the general population.

Then, in 1957, a new pandemic struck. The "Asian flu," although not as severe as the 1918 pandemic, would eventually cause 1-2 million deaths worldwide.[10] A vaccine was manufactured, and millions of doses were administered in the United States in response.[11] The vaccine had no appreciable effect on the trend of the pandemic.[12]


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.