October is the prime time to get a flu vaccine to protect yourself through the worst of the respiratory season. However, keep your expectations in check. This year’s shot may be less effective than last year’s at preventing severe disease.
Newly released data from the Southern Hemisphere, where flu season typically runs from April through September, suggests that this year’s flu vaccines offer 34% efficacy against hospitalization, compared with 50% last year. Overall, though, an evaluation of hospitalizations from places like Brazil, Argentina, Chile, Uruguay and Paraguay suggests that people who were vaccinated for influenza were at significantly lower risk for hospitalization from a severe respiratory infection than those who did not get a flu shot. The annual influenza vaccine targets three strains of seasonal flu, and scientists make an educated guess months before the fall season.
It takes about six months for pharmaceutical makers to produce the flu vaccine. They try to create a formula that they believe will align perfectly with the circulating strains. In some years, scientists have been more on target than others.
The big question is whether the same influenza viruses will predominate during the 2024-25 U.S. flu season as in the Southern Hemisphere.
“We know this is what happened in the Southern Hemisphere during their flu season, but patterns there don’t always predict how the season will unfold in the United States,” said Dr. Bharvarth Shukla, an associ.
