What to Know about that Bombshell Cleveland Clinic Study on Flu Vaccine Effectiveness
Far from a bombshell — the Cleveland Clinic preprint on flu vaccine effectiveness is just another dud, while anti-vaccine influencers ignore all the unvaccinated children who are dying with flu.
A new preprint about the Effectiveness of the Influenza Vaccine During the 2024-2025 Respiratory Viral Season has anti-vaccine influencers very excited.
A preprint (has not undergone peer review) that is claiming that “Among 53402 working-aged Cleveland Clinic employees, we were unable to find that the influenza vaccine has been effective in preventing infection during the 2024-2025 respiratory viral season.”
What to Know about that Bombshell Cleveland Clinic Study on Flu Vaccine Effectiveness
A preprint whose conclusions were quickly dismissed by many experts.
Dismissed because of the inherent bias in the study created by using an unvaccinated group made up of folks who were using exemptions to get out of the hospital’s flu vaccine mandate.
“For several years Cleveland Clinic has had a mandatory participation influenza vaccination program, which requires employees to either receive an annual influenza vaccine or seek an exemption on medical or religious grounds.”
Effectiveness of the Influenza Vaccine During the 2024-2025 Respiratory Viral Season
How does that create bias?
Well, if you didn’t want a flu shot, you might not faithfully participate in a flu shot study!
“The ratio of the proportion of the vaccinated who got tested to the proportion of the unvaccinated who got tested for influenza on each day of the study was significantly higher than 1.00 for most of the study (Figure 1), suggesting that the vaccinated were more likely to be tested than the unvaccinated on any given day.”
Effectiveness of the Influenza Vaccine During the 2024-2025 Respiratory Viral Season
The researchers dismiss the fact that the vaccinated got tested more, saying that it was because of “a higher number of infections,” but it could have been that fewer unvaccinated were coming in to get tested when they were sick.
“If controls are selected from a different population than the cases (e.g., cases are from a health clinic and controls from a community sample) with different health care seeking behaviors, selection bias related to health care seeking (and the likelihood to be vaccinated) may be introduced.”
Biases to Consider in Vaccine Effectiveness Studies
Anyway, it is one preprint…
“Among children and adolescents aged <18 years, VE against any influenza was 32%, 59%, and 60% in the outpatient setting in three networks, and against influenza-associated hospitalization was 63% and 78% in two networks. Among adults aged ≥18 years, VE in the outpatient setting was 36% and 54% in two networks and was 41% and 55% against hospitalization in two networks.”
Interim Estimates of 2024–2025 Seasonal Influenza Vaccine Effectiveness — Four Vaccine Effectiveness Networks, United States, October 2024–February 2025
One preprint with results that are very different from that of other published studies on this year’s flu vaccine effectiveness.
“Preliminary estimates indicate that receipt of the 2024–2025 influenza vaccine reduced the likelihood of medically attended influenza and influenza-associated hospitalization.”
Interim Estimates of 2024–2025 Seasonal Influenza Vaccine Effectiveness — Four Vaccine Effectiveness Networks, United States, October 2024–February 2025
That alone should lead you to question their methodology, not jump to embrace their conclusions just because it fits your anti-vaccine agenda.
The preprint might be getting a lot of attention as anti-vaccine influencers launder it through their social media accounts and websites to draw attention away from the fact that unvaccinated children are dying with measles, but know that it is neither a landmark nor a bombshell.
“This season is classified as a high severity season overall and for all age groups (children, adults, older adults) and is the first high severity season since 2017-2018.”
Weekly US Influenza Surveillance Report: Key Updates for Week 13, ending March 29, 2025
And the only serious questions about this past year’s flu season that you should have is, why are so many kids dying with flu?
As of early April, there have already been 168 flu deaths in kids.
And why are so few kids getting vaccinated and protected against the flu?
Is it because their parents have been listening to anti-vaccine influencers telling them that the flu vaccine doesn’t work?
“Nine pediatric influenza-associated deaths with IAE were reported to CDC during the 2024–25 season through February 8, 2025; four had documented ANE (two ANE deaths were proactively reported to CDC by state health departments, and two additional deaths were identified during CDC outreach to states). All four ANE deaths were aged <5 years; one child had underlying medical conditions, and all four had laboratory-confirmed influenza A(H1N1)pdm09.”
Reports of Encephalopathy Among Children with Influenza-Associated Mortality — United States, 2010–11 Through 2024–25 Influenza Seasons
Anti-vaccine influencers who never mention things like death from influenza-associated encephalopathy or encephalitis (IAE).
A complication of the flu that mainly occurs in those who are not vaccinated…
References
Effectiveness of the Influenza Vaccine During the 2024-2025 Respiratory Viral Season. Nabin K. Shrestha, Patrick C. Burke, Amy S. Nowacki, Steven M. Gordon medRxiv 2025.01.30.25321421; doi: https://doi.org/10.1101/2025.01.30.25321421
CDC Seasonal Flu Vaccine Effectiveness Studies. https://www.cdc.gov/flu-vaccines-work/php/effectiveness-studies/index.html
Weekly US Influenza Surveillance Report: Key Updates for Week 13, ending March 29, 2025 https://www.cdc.gov/fluview/surveillance/2025-week-13.html
Fazal A, Reinhart K, Huang S, et al. Reports of Encephalopathy Among Children with Influenza-Associated Mortality — United States, 2010–11 Through 2024–25 Influenza Seasons. MMWR Morb Mortal Wkly Rep 2025;74:91–95. DOI: http://dx.doi.org/10.15585/mmwr.mm7406a3.
Biases to Consider in Vaccine Effectiveness Studies. https://www.cdc.gov/flu-vaccines-work/php/effectivenessqa/biases-to-consider.html
CDC: 13% of kids who died from flu this year had brain damage. https://www.cidrap.umn.edu/influenza-general/cdc-13-kids-who-died-flu-year-had-brain-damage
What is it with the Cleveland Clinic? This is not the first time they have done awful studies, there was something similar with COVID vaccination.
Seriously if not getting vaccinated would weed out the fucking gene pool of morons forever. Bring it on. So tired of trying to be logical and calm with these stupid assholes