Flu season is upon us, and hitting hard. That’s one reason American health officials are urging people to get vaccinated.
Some media reports have speculated that this year’s flu shot will only be about 10% effective for Americans, based on results seen in Australia during its flu season. The US Centers for Disease Control and Prevention (CDC) said it expects this year’s effectiveness rate to be closer to last year’s number, between 32% and 39%.
“It’s not possible to predict with certainty if the flu vaccine will be a good match for circulating flu viruses,” the agency says. The flu vaccine is made to protect against the flu viruses that…will likely be most common during the season. However, experts must pick which flu viruses to include in the flu vaccine many months in advance in order for flu vaccines to be produced and delivered on time.”
Because circulating flu virus strains change, it’s difficult for health agencies to predict how bad flu season will be in a given year. Every February, a group of researchers from around the world meets at the World Health Organization to pin down three or four flu strains that might infect people in the Northern hemisphere during the following winter. In September, they consider the Southern hemisphere.
Despite a lack of certainty, health officials generally agree that the best way to protect a population is for as many people as possible to get the shot and participate in what scientists call “herd immunity.” When more people in a society become immune to a virus—or any disease—chances decrease that someone who isn’t immune will be exposed. That could mean the difference between life and death for some people who have weaker immune systems—including the elderly, young children, and people with chronic medical conditions.
During the 2014-15 flu season, which was particularly severe, more than 700,000 people were hospitalized. “Flu seasons every year are bad so there’s never a mild flu season,” said Dan Jernigan, director of the CDC’s influenza division on a Jan. 12 call with reporters. “This season is on that more severe side…all the more reason to take those precautions.”
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