Clinical Trials Aren’t the Only Way to Know if Flu Shots Work

Earlier this year, the U.S. Department of Health and Human Services (HHS) stopped recommending that all children get an annual influenza vaccine. Instead, it made the shot a matter of “shared clinical decision-making”—something for parents and a doctor to weigh case by case—citing, among other reasons, a lack of randomized controlled trials proving the vaccine’s efficacy in children, including the very young.After a lawsuit from public health organizations, a federal court blocked it, leaving the previous recommendation in place. But the case is ongoing, and earlier this year President Donald Trump issued an executive order directing the government to treat a recent HHS assessment as a “guiding resource” and to revisit the childhood vaccine schedule. That assessment argues that recent evidence behind annual flu shots for children, much of it from observational studies rather than randomized trials, is thin. While we believe that the evidence base, which in fact includes many clinical trials, is stronger than suggested by that assessment, it is correct to note that observational studies of annual flu shots suffer from various statistical biases.In a new study published this summer, ...