Vaccinate Your Family is excited to feature a series from Voices for Vaccines “Just the Facts” that breaks down common vaccine questions and misinformation using clear, evidence-based explanations. Adapted with credit to Voices for Vaccines, these installments are designed to help partners, community health workers, and families evaluate claims they may see online. Each post will focus on a specific topic and provide straightforward facts that support confident and informed decision-making. To learn more about Voices for Vaccines, visit their website here.
Adapted with credit to Voices for Vaccines. Originally published October 30, 2025
The Claim:
On his online show, Del Bigtree claims that a Cleveland Clinic study found people who got last year’s flu shot were more likely to catch the flu than those who didn’t. He also criticizes doctors for recommending the vaccine without knowing this and suggests people stop trusting them.
The Facts:
A recent study from the Cleveland Clinic was released as a preprint. This means it has not yet gone through peer review, the process where other scientists carefully check a study to confirm that the methods and conclusions are reliable. Because that review has not happened, the authors clearly state that the study “should not be used to guide clinical practice.” In other words, doctors should not use the study to make medical decisions at this stage.
There were also limitations in the study. One major concern was selection bias, meaning the group of people included may not fairly represent everyone. For example, people who get the flu shot may be more likely to visit a doctor or get tested when they feel sick, while those who are unvaccinated may be less likely to get tested at all. This can make it appear that more vaccinated people have the flu even if that is not actually the case.
Another issue is that the study only looked at how many people tested positive for flu, not how sick they became. A key goal of the flu vaccine is to prevent severe illness. Even if someone still gets the flu after being vaccinated, they are usually less likely to experience complications or require hospitalization. For instance, a vaccinated person might have mild symptoms for a couple of days, while an unvaccinated person could develop a high fever and be bedridden for a week. The vaccine also helps reduce the risk of serious complications like pneumonia, especially in older adults and people with chronic health conditions.
Since the study did not look at these more important health outcomes, it does not provide the full picture of how the flu vaccine protects people. More rigorous research is needed before drawing conclusions about the vaccine’s effectiveness.
Science is always evolving and our understanding may have changed since this was originally posted. For the most up-to-date information, review the latest Just the Facts topics from Voices for Vaccines.
Content adapted from Voices for Vaccines with credit to their “Just the Facts” series.