Insights From the Northern Hemisphere's Flu Season 2022

The Georgia-based U.S. Centers for Disease Control and Prevention (CDC) recently reported the seasonal influenza vaccines selected for the 2021-2022 flu season were suboptimal at reducing outpatient respiratory illnesses caused by influenza A(H3N2) viruses.

The CDC’s Morbidity and Mortality Weekly Report (MMWR) found the overall vaccine effectiveness (VE) against medically attended outpatient acute respiratory infection (ARI) associated with influenza A(H3N2) virus was 16% (95% CI = −16% to 39%), which was considered not statistically significant.

This CDC analysis dated Mar. 11, 2022, indicates that this season’s flu shots did not successfully reduce influenza risk.

However, the MMWR reported some good news too.

There were very few influenza infections reported during the 2021-2022 season.

Among the 3,636 children and adults enrolled at the seven study sites during October 4, 2021–February 12, 2022, a total of 194 (5%) received a positive test result for influenza A virus infection, and none received a positive test result for influenza B virus infection.

From a real-world perspective, this data indicates there were not enough flu cases actually to evaluate influenza vaccine effectiveness this season.

Previously, Lisa Grohskopf with the CDC's Influenza Division confirmed this assumption on March 4, 2022, when she presented:

• The lowest influenza positivity (5%) was observed over the past ten seasons among Flu VE Network participants with respiratory illness,
• The numbers of influenza-positive participants were insufficient to estimate age group-specific VE or compare the effectiveness of different influenza vaccine products against the predominant A(H3N2) virus.

Predicting the future flu viruses impacts the composition of influenza vaccines produced each season.

The best news is the CDC, U.S. FDA, and the World Health Organization (WHO) have taken early action to improve VE results for the 2022-2023 flu season.

The WHO published its recommended composition of influenza virus vaccines for use in the 2022-2023 Northern Hemisphere influenza season on February 25, 2022.

The new changes apply to egg-based, cell culture, recombinant vaccines, and for both quadrivalent (four-strain) and trivalent (three-strain) vaccines.

And the FDA Vaccines and Related Biological Products Advisory Committee has already selected the influenza vaccine strains for the 2022–2023 season in the Northern Hemisphere.

To enhance consumer understanding, the CDC recently published updated influenza vaccine schedules for children and adults for the rest of 2022.

Since flu viruses are unpredictable and a global issue, the CDC suggests that most people older than six months stay protected with a flu shot, except when contraindicated.

To keep current on influenza vaccine news, visit PrecisionVacinations.com/flu.

PrecisionVaccinations publishes fact-checked research-based influenza vaccine news.

Note: This news article aggregated content from various CDC sources and edited them to render a mobile user experience. And these CDC researchers did not disclose any industry conflicts of interest.