Each week, OMRF Vice President of Research Dr. Rod McEver opens “Adam’s Journal” to answer a medical question from Adam Cohen, OMRF’s senior vice president & general counsel.
I know health officials sometimes caution people not to get the influenza vaccine too early so that protection doesn’t wear off before flu season ends. How long does immunity from a flu shot last? Would a booster after the first shot help?
Dr. McEver Prescribes
For this question, I consulted Judith James, M.D., Ph.D., who has studied the influenza vaccine at the Oklahoma Medical Research Foundation. Dr. James is an immunologist, board-certified rheumatologist, and OMRF’s vice president of clinical affairs. Here’s what she said:
Flu activity in the U.S. usually increases in early fall and peaks from December to February. Those who get a flu vaccine before November should have adequate protection against severe disease and death through spring. Although two doses may sound better than one, flu boosters are currently only recommended for young children.
How long a flu shot lasts depends on individual immune systems, but the vaccine is usually effective for 6-8 months. Immunity wanes toward the end of our flu season. All viruses mutate, but influenza viruses do so rapidly. This perpetual viral drift necessitates the annual flu vaccine.
Studies of second doses of flu vaccine in one season have shown no benefit for most adults. But among the very young, it’s a different story.
For children ages 6 months to 8 years getting their first flu shot, the Centers for Disease Control and Prevention recommends two doses spaced at least four weeks apart. For a young immune system that hasn’t seen the flu before, this booster dose of vaccine is important to the body’s ability to mount a protective response when it encounters the virus.
This double dose of protection for kids may impact their likelihood of contracting the flu in future seasons. In a 2016 study in the Pediatric Infectious Disease Journal, researchers found young children who’d received two doses during a prior season were only half as likely as their peers to contract flu the next year.
Do you have a health query for Dr. McEver? Email firstname.lastname@example.org and your question may be answered in a future column!