Sep 8, 2023
Early Flu Shot Data Shows Effectiveness Against Hospitalization
, Bloomberg News
(Bloomberg) -- Flu shots reduced people’s risk of being hospitalized for the disease by about half, according to early data from countries south of the equator, a positive sign for the US and Europe where the upcoming season is still on the horizon.
Influenza vaccines formulated to target circulating flu strains were 52% effective at preventing hospitalizations in young children and older adults in the Southern Hemisphere, according the US Centers for Disease Control and Prevention, roughly in line with how the shots usually perform. Flu season for countries like Argentina, Brazil and Chile typically runs from to March to July.
“This report might help health officials in Northern Hemisphere jurisdictions prepare for a potentially early influenza season and highlight the benefits of vaccination,” the CDC said.
The CDC recommends that everyone 6 months and older get an influenza vaccine every season, although young children and older adults are at highest risk of severe complications and death. Sanofi, GSK Plc, CSL Ltd., AstraZeneca Plc and other companies make seasonal flu shots.
Twice a year, health experts from around the world convene to make recommendations about which strains of influenza the season’s vaccines should target. While effectiveness varies from year-to-year, depending on how well-matched the vaccines are to strains, flu shots typically reduce the risk of serious illness by 40% to 60%.
Vaccines for the Northern Hemisphere flu season that begins in October and lasts through May are usually very similar to the ones used in the south. So far, early flu cases identified in the US appear to be caused by the same strains of flu that were dominant in the Southern Hemisphere, the CDC said, “providing an encouraging outlook for vaccine protection.”
Whether these strains will remain dominant in the US as flu season ramps up is still unclear, the CDC said.
“I think these results bode well,” said Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia. “Influenza is hard. The virus continues to evolve not only from one year to the next, but during the winter season and even during a single infection.”
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