Now might be the best time to get your flu shot.
There is mounting evidence that vaccine protection diminishes over the course of a single season since getting the flu shot, meaning an individual vaccinated in early September may be more vulnerable than someone vaccinated in late October when flu season hits.
A recent study published in Clinical Infectious Diseases found that an eight-week delay in vaccination might prevent about nine flu cases for every 1000 persons vaccinated during an average season. These findings backup previous research, including a 2017 study by CDC scientists that found vaccine effectiveness for strains of H1N1 declined up to 11 percent each month after administration.
"We're balancing two things. One is coverage of how many people get the vaccine every year. The CDC recommends everyone over six months of age get the flu vaccine – it's truly our best weapon to protect against this deadly disease. The other thing we're balancing is when is the best time to get the vaccine," said Kunal Rambhia, a University of Michigan graduate student who recently co-authored a paper in Clinical Infectious Diseases titled "Early Bird Gets the Flu." His study summarized 11 studies over the last several years that show evidence for this single-season waning immunity.
Over the past decade, vaccines have become available earlier in the season in efforts to increase coverage, especially as large pharmacy chains started offering them. But because flu season tends to peak in December or later, individuals who got vaccinated during July or August may not be protected the entire season.