Flu Shots Remove One Influenza Virus Strain

An independent committee of vaccine experts unanimously endorsed removing one influenza virus strain from future influenza vaccines.

On October 5, 2023, the Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted to eliminate the influenza B/Yamagata lineage viruses since it has not been detected for about three years.

The VRBPAC vote follows the World Health Organization's recent announcement that it endorsed eliminating the influenza B/Yamagata/16/88 lineage component from the 2024 Southern Hemisphere flu shot formulation.

Flu seasons in the Southern Hemisphere usually occur between April and September, while the Northern Hemisphere's is generally between October and May.

This change should not impact the effectiveness of flu shots.

A recent U.S. CDC report found the adjusted vaccine effectiveness against severe acute respiratory infection hospitalization associated with any influenza virus during the 2023 Southern Hemisphere flu season was 51.9% (95% Confidence Interval 39.2%–62.0%).

For the 2023-2024 flu season in the U.S., there should be ample supply of vaccines at health clinics and pharmacies. According to a report by the Global Healthy Living Foundation and IQVIA, about 60% of vaccinations during the 2022 flu season took place at pharmacies in the U.S.

Vaccine manufacturers have projected to supply as many as 156.2 million to 170 million doses of influenza vaccines for the 2023-2024 season.

As of September 23, 2023, the CDC says about 100 million doses had been distributed in the U.S. All influenza vaccines are quadrivalent for this flu season, such as FLUMIST® and FLUCELVAX®.