THURSDAY, May 19, 2022 (HealthDay News) -- Getting a COVID-19 shot after you've been infected could reduce your risk of developing prolonged COVID symptoms, or so-called long COVID, according to a new study.
"Our results suggest that vaccination of people previously infected may be associated with a reduction in the burden of long COVID on population health, at least in the first few months after vaccination," co-author Daniel Ayoubkhani, of the U.K. Office for National Statistics, and colleagues wrote.
For the study, the researchers analyzed data on more than 28,000 adults, aged 18 to 69, in the United Kingdom who received at least one COVID-19 vaccine dose after testing positive for infection.
Over seven months of follow-up, 24% of participants reported long COVID symptoms of any severity at least once. Before vaccination, there was little change in their chances of experiencing long COVID.
A first vaccine dose was associated with an initial 13% decrease in the likelihood of long COVID, but whether this reduction was sustained until the participants received another vaccine dose 12 weeks later is unclear.
A second vaccine shot was associated with a further 9% decrease in the odds of long COVID, and this was sustained for at least an average follow-up of nine weeks.
Similar results were also found when the researchers focused on long COVID severe enough to limit day-to-day activities, according to the study. The results were published online May 18 in the BMJ.
Because it's an observational study, it can't prove that getting vaccinated after infection protects against long COVID, the authors said in a journal news release.
However, they noted that their results were consistent after they accounted for income levels, health-related factors, vaccine type and length of time between infection and vaccination.
The researchers called for further research into the long-term connection between vaccination and long COVID, and more studies "to understand the biological mechanisms underpinning any improvements in symptoms after vaccination, which may contribute to the development of therapeutics for long COVID."
While questions remain about whether vaccination after infection may help protect some people against long COVID, it's clear that vaccination to reduce the risk of reinfection is important for people with long COVID, Manoj Sivan and colleagues said in an accompanying editorial. Sivan is with the University of Leeds in England.
"Unfortunately, many unknowns remain about the long-term prognosis of long COVID, including the effect of booster vaccines or recurrent COVID-19," the editorialists wrote. More research is required "before we can hope to predict the effects of vaccination on individuals," they added.
The U.S. Centers for Disease Control and Prevention has more on COVID vaccines.
SOURCE: BMJ, news release, May 18, 2022