Are Influenza Vaccine Failures One Reason for Declining Flu Shot Uptake?

The rates of adults and children in the United States receiving influenza vaccinations have been steadily declining in recent years, according to the U.S. Centers for Disease Control and Prevention (CDC). During the 2019-2020 “flu season,” 63.7 percent of American children between six months to 17 years of age received flu shots, compared to 55.4 percent in 2023-2024. During 2019-2020, 48.4 percent of adults in the country got flu shots, compared to 44.9 percent in 2023-20024.^{1 2}

“It’s a really disappointing trend,” said Jonathan Miller, MD, chief of pediatric primary care at Nemours Children’s Health in Wilmington, Delaware. “I suspect that the COVID pandemic and the sort of political milieu during this time has had a lot of impact on vaccine confidence and an increase in vaccine hesitancy.”²

Vaccination “Fatigue” and Fear of COVID Shot Failures May Be Factors

Another factor that is often cited for the drop in flu vaccinations is what some public health officials call post-COVID “vaccination fatigue.” For the past four years, people in the U.S. have been urged to get COVID-19 shots and boosters. Many are simply tired of getting so many shots in such a short period of time. “It’s also fatigue due to the COVID vaccines not being particularly effective at preventing symptoms, which causes people to believe that [vaccines] are not effective,” said Jacob Glanville, PhD, CEO of biotechnology company Centivax, Inc. in San Francisco.^{2 3}

“I think a lot of fatigue stems from the pandemic and the fear that it generated,” noted internist Kathryn Glassberg, MD with Kaiser Permanente Northwest in Portland, Oregon. Some of that fear may have something to do with the widely reported serious adverse reactions to the COVID shots, and this certainly could, at least indirectly, affect attitudes toward flu vaccinations.^{4 5 6 7 8 9 10 11 12 13 14}

A study released last year by KFF (formerly Kaiser Family Foundation) of San Francisco found that one-third of adults believed that the COVID shots “caused thousands of sudden deaths in otherwise healthy people.”¹⁵

CDC Estimates Effectiveness of Flu Shots at 34.5 Percent

Then, of course, there is the effectiveness, or ineffectiveness, of the influenza vaccines that may helping fuel “vaccine hesitancy” toward them. The CDC recently came out with its interim estimate for the effectiveness of the influenza vaccines for the current flu season (2024-2025), and it’s not good—34.5 percent.^{16 17}

The CDC based its estimate on data from the southern hemisphere, specifically involving the predominance of the influenza A virus subtype H3N2 (and to a lesser degree, A(H1N1) in five South American countries (Argentina, Brazil, Chile, Paraguay, and Uruguay). In what sounds like classic understatement, Kawsar Talaat, MD, of Johns Hopkins University in Baltimore admitted the rate is “a little bit disappointing.”^{16 17 18} She added:

This is on the lower end of what would be expected but not outside the range.¹⁸

Dr. Talat, however, noted:

It’s very early here… We’re not seeing a lot of flu. We might have different virus (strains) and different proportions.¹⁸

This suggests that effectiveness rate for the shots may eventually go up. Or, on the other hand, it could be even lower. During the 2023-2024 flu season, the shots were reportedly 42 percent effective. The last time the effectiveness rate was lower than 34.5 percent was in 2018-2019 when it was only 29 percent. But it has been worse than that. Particularly poor performances for influenza vaccines occurred in 2004-2005, 2005-2006 and 2015-2016, when the shots turned out to be only 10 percent, 21 percent and 19 percent effective respectively.^{16 19 20}

Nine Licensed Influenza Vaccines. All Contain Allergens.

There are nine influenza vaccines that are licensed by the U.S. Food and Drug Administration (FDA) for distribution during the 2024-2025 flu season, including the Afluria Quadrivalent (produced by Sequris), Fluad Quadrivalent (Sequris), Fluarix Quadrivalent (GSK), Flublok Quadrivalent (Sanofi Pasteur), Flucelvax Quadrivalent (Sanofi Pasteur), FluLaval Quadrivalent (Sanofi Pasteur), FluMist Quadravalent (MedImmune), Fluzone Quadrivalent (Sanofi Pasteur) and Fluzone High-Dose Quadrivalent (Sanofi Pasteur).²¹

Each of these influenza vaccines contains at least one ingredient that is a potential allergen…

• Alfuria contains the mercury-based preservative thimerosal (multiple-dose vials), egg protein, neomycin and polymyxin.
• Fluad contains egg protein, kanamycin, neomycin and polysorbate 80.
• Fluarix contains egg protein, gentamicin and polysorbate 80.
• Flublok contains polysorbate 20.
• Flucelvax contains thimerosal (multiple-dose vials) and polysorbate 80.
• FluLaval contains egg protein and polysorbate 80.
• FluMist contains egg protein, gentamicin, pork gelatin, monosodium glutamate (MSG) and ethylenediaminetetraacetic acid (EDTA).
• Fluzone contains egg protein.
• Fluzone High-Dose contains thimerosal (multiple-dose vials) and egg protein.²¹

For the sake of clarification, by “effective,” the CDC is referring to reducing the risk of influenza-related hospitalizations or “medically attended influenza virus infection,” not actually preventing influenza infections.¹⁹

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