This Year's Flu Vaccine Prevents Illness About Half The Time

Feb 21, 2020

This season’s flu vaccine is effective about 45 percent of the time, according to preliminary data from the Centers for Disease Control and Prevention.

That's much better than last year, when the vaccine worked 29 percent of the time.

Vaccines are developed roughly a year out from each flu season. Since the virus mutates rapidly, picking the right viral strain to develop an inoculation for is a challenge.

“It’s like trying to hit a moving target,” said the University of Pittsburgh's Dr. Richard Zimmerman, who heads one of the five CDC sites that study flu vaccine effectiveness.

The flu is very common, so physicians stress it remains the public’s best bet for staying healthy, even if it only prevent illness about half the time.

“The results of that,” he said, “is reduction in millions of illnesses, millions of medical visits, likely 100,000 or more hospitalizations, and 1,000s of deaths prevented.”

Interestingly, Zimmerman said that data show the vaccine has a higher level of efficacy in Canada.

“It does raise questions, what’s happened?” he said.

Final results of the vaccine’s effectiveness will be presented at the CDC’s June meeting.