New flu data from the southern hemisphere suggests this year’s vaccine isn’t as effective against severe illness as previous iterations, a finding that may not bode well for Americans as the nation kicks off flu season.
Researchers tracked the vaccine’s effectiveness in five South American countries – Argentina, Brazil, Chile, Paraguay and Uruguay – during their flu season from March to July.
They found flu shots reduced the risk of hospitalizations by about 34%, according to the study published Thursday in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.
Public health experts typically expect flu vaccines to reduce hospitalization risk by closer to 50%, said Dr. Kawsar Talaat, associate professor of international health at the Johns Hopkins Bloomberg School of Public Health.
“It’s a little bit disappointing,” she said. “This is on the lower end of what would be expected but not outside the range.”
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