CDC: Flu vaccine's 52% efficacy in Southern Hemisphere could indicate potency in U.S.

Sept. 8 (UPI) -- The Centers for Disease Control and Prevention said Friday that said the 2023 Southern Hemisphere seasonal influenza vaccine reduced the risk for flu-related hospitalizations by 52% -- a possible indicator of its efficacy in the United States this fall and winter.

The CDC said the results came from early seasonal data in which investigators collected mid-season flu vaccine data in five South American countries during their 2023 flu season.

"Circulating influenza viruses were genetically similar to those targeted by the 2023-24 Northern Hemisphere influenza vaccine formulation," the report said. "This vaccine might offer similar protection if these viruses predominate during the coming Northern Hemisphere influenza season."

The CDC said to lower the risk of influenza, particularly to those with the most vulnerable immune systems, it is suggesting that healthcare providers administer the seasonal influenza vaccine to all eligible persons aged above 6 months old.

While the flu accounts for up to 829,000 respiratory hospitalizations annually and as many as 71,710 deaths, vaccination coverage has been dropping since 2016.

The CDC said educating the public about the effectiveness of the vaccines could be one way to encourage the public to get vaccines and improve coverage rates.

"While what happens in the Southern Hemisphere is not always a predictor of what will happen in the United States," the report noted,

"if similar flu viruses continue to spread and predominate in the U.S. this upcoming flu season, U.S. flu vaccines could provide similar protection against severe illness resulting in hospitalization this fall and winter."

The CDC recommends it is particularly important for those with "very young children, people with preexisting health conditions, pregnant people and older adults" to be vaccinated for flu.

The agency said the best time to receive a flu vaccination is September and October.