US adults who get annual flu shots 25% more likely to get COVID vaccine - CIDRAP

US adults who get vaccinated against the flu every year were 24.7% more likely to complete a primary COVID-19 vaccine regimen than those who never received the flu vaccine, finds a study yesterday in JAMA Network Open.

Rand Corp. researchers used their American Life Panel, a probability sample of US adults, to analyze self-reported flu vaccine uptake in the 2009 to 2017, 2019-20 (largely prepandemic), and 2021-22 (pandemic) flu seasons. The team also evaluated COVID-19 vaccine status during the latter two seasons.

Of 1,366 survey respondents, 85% were White, 11% were Hispanic, 7% were Black, and 2% were Asian. Average age was 56 years.

Among 358 participants who always received the flu vaccine through 2017, 81.4% to 92.2% still did so two to four seasons later. But of 642 respondents who never received the flu vaccine, only 20.3% received it in 2019 to 2020, rising to 23.5% during the pandemic. Those who always got the flu shot were 24.7% more likely to be vaccinated against COVID-19 than those who never did so.

COVID-19 vaccination was 50% more common in respondents vaccinated against the flu in 2021-22 (90.8% of 944 vs 60.9% of 723; risk ratio [RR], 1.50). And flu vaccine uptake in 2021-22 was 230% higher among COVID-vaccinated participants (57.1% of 1,025 vs 17.3% of 341; RR, 3.30).

COVID-19 vaccinees were much more likely to receive the flu vaccine in 2022 after not receiving it in 2020 (odds ratio [OR], 12.82). Recipients of both vaccines had higher educational attainment, while Democrats were more likely than Republicans to receive the COVID-19 vaccine (OR, 4.43) but not to switch from not receiving to receiving the flu vaccine.

"Most strikingly, among individuals who historically never got the influenza vaccine, those receiving COVID-19 vaccine were substantially more likely to switch toward getting the influenza vaccine," the authors wrote. "This suggests that investing in vaccine acceptance has payoffs beyond the vaccine itself."