In any given flu season, vaccine effectiveness varies. One factor is how well the vaccines match the virus that is actually prevalent. Other factors influencing effectiveness include the age and general health of the recipient. In the overall population, the CDC says studies show vaccines can reduce the risk of flu by about 50 to 60 percent when the vaccines are well matched.
Health officials say it’s especially important to vaccinate children because they often spread the disease, are better able to develop antibodies from the vaccines and, if they don’t get sick, they won’t expose grandma and grandpa. While most people who get the flu recover, it is a serious disease responsible for many deaths each year, particularly among older adults and young children. Influenza’s intensity varies annually, with the CDC saying deaths associated with the flu have ranged from about 3,300 a year to 49,000 during the past 31 seasons.
To develop vaccines, manufacturers and scientists study what’s circulating in the Southern Hemisphere during its winter, which is our summer. Then — based on that evidence — forecast what flu strains might circulate here to make vaccines that are generally delivered in late July.
For the upcoming season, the vaccines will include three or four strains, including two A strains, an H1N1 and an H3N2, as well as one or two B strains, according to the CDC. It recommends that everyone older than 6 months get vaccinated, unless they have health conditions that would prevent it.
The vaccines can’t give a person the flu because the virus is killed before it’s included in the shot. This year, the nasal vaccine is not recommended for use, as studies showed it was not effective during several of the past flu seasons.
But when to go?
“The ideal time is between Halloween and Thanksgiving,” said Haynes at UConn. “If you can’t wait and the only chance is to get it in September, then go ahead and get it. It’s best to get it early rather than not at all.”
This Kaiser Health News story also ran on NPR.