CDC Updates Flu Vax Efficacy: Negligible Immunity Increases to Moderate 35 Percent Efficacy

By Marina Zhang
Marina Zhang
Marina Zhang
Marina Zhang is based in New York and covers health and U.S. news. Contact her at
July 5, 2022 Updated: July 5, 2022

Estimation of the influenza vaccine’s efficacy has increased from negligible to moderate, improving to 35 percent in vaccine efficacy, according to the Centers for Disease Control and Prevention (CDC) on June 22.

The CDC announcement backtracked on its previous interim estimates in March for 2021 to 2022 seasonal influenza found that the vaccine did not offer significant immunity, with estimated immune protection of 16 percent.

“Seasonal influenza vaccination did not reduce the risk for outpatient respiratory illness,” wrote the authors of the March study.

Nonetheless, the same authors also encouraged the uptake of influenza vaccines despite insignificant scientific evidence of benefit, with a projected vaccine uptake of 188 to 200 million doses among Americans.

Though CDC claims that recent flu vaccine efficacy hovered in the range of 40 to 60 percent efficacy, other reports have shown a 30 to 40 percent vaccine efficacy instead, way below the recommended level for vaccine efficacy.

The CDC now says that the influenza vaccine offers moderate protection against the virus by reducing mild to moderate symptoms by 35 percent.

The World Health Organization’s website wrote that vaccines need to have at least 50 percent efficacy to be approved; this statement is in stark contrast to the reality of approved vaccines with vaccine efficacy dropping below 50 percent, sometimes with even insignificant efficacy.

Declining Flu Vaccination Rates: An Aftermath of COVID-19 Vaccination

Since February, data from the CDC has shown that vaccination uptake has seen a significant drop for the 2021 to 2022 season, even for those that are of “increased risk of flu complications.”

Similar results have also been observed in a study by the University of California, finding a drop in influenza vaccination rate to be the most significant in states that had low COVID-19 vaccination rates.

They suggest that the drop in influenza vaccination may have been due to the public’s attitudes toward COVID-19 spilling into public health. Those that think unfavorably of COVID-19 vaccines may also extend these sentiments to other vaccines administered by the general health care sector.

“Many Americans who never before declined a routine, potentially life-saving vaccine have started to do so,” said the study’s lead author Dr. Richard Leuchter in the university’s media release.

The authors proposed “belief generalization” as the reason, giving the example of how someone may not wear a mask to signal their beliefs publicly, those that oppose or support the COVID-19 vaccine may also “feel that they should, in turn, oppose or support other vaccines.”

Though the study did not make any direct associations between specific influenza vaccination decreases with pandemic policies and the promotion of COVID-19 vaccines, it indicated that “safety concerns and mistrust of COVID-19 vaccines or government” may have been factors associated with the COVID-19 vaccination rates and the decrease in influenza vaccine uptake.