Long COVID symptoms could be alleviated in some people through vaccination, researchers report today.
Writing in the latest edition of *The BMJ*, the authors, who include researchers from the Office for National Statistics (ONS), University of Leicester, University of Oxford and the University of Southampton, say vaccination after infection with SARS-CoV-2 is associated with a decreased risk of developing long-COVID symptoms.
However, the research team stress more data are needed before they can come to any firm conclusions, saying vaccination “may contribute to a reduction in the population health burden of long-COVID, at least in the first few months after vaccination”.
While COVID-19 vaccines are effective at reducing rates of infection, transmission, hospital admission, and death, there is also evidence that long-COVID is reduced in those who are infected after vaccination. The effectiveness of vaccination on pre-existing long-COVID remains unclear.
The latest survey by the ONS shows 44% of people who report long-COVID have had symptoms for at least one year, of whom two thirds say their symptoms are severe enough to limit their day-to-day activities.
For this study, to estimate associations between COVID-19 vaccination and long-COVID symptoms in adults with SARS-CoV-2 infection before vaccination, the researchers used ONS data for 28,356 adults aged 18-69 years who received at least one COVID-19 vaccine dose after testing positive for SARS-CoV-2 infection.
The average age of the cohort was 46, with 56% of participants being women and 89% white.
The team tracked the presence of long-COVID symptoms between February and September 2021 and symptoms of any severity were reported by 6,729 participants (24%) at least once.
The odds of experiencing long-COVID before receiving a first vaccination changed little over time, but a first vaccine dose was associated with an initial 13% decrease in the odds of long-COVID.
However, it is unclear from the data whether this improvement was sustained over the following 12 weeks, until a second vaccine dose was given.
Receiving a second vaccine dose was associated with a further 9% decrease in the odds of long-COVID, and this improvement was sustained at least over an average follow-up of nine weeks.
Similar results were also found when the focus was on long-COVID severe enough that individuals had to limit their day-to-day activities.
Although the study is observational, the authors say the results were consistent after taking account of sociodemographic characteristics, health related factors, vaccine type, or duration from infection to vaccination, suggesting that they withstand scrutiny.
“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,” they write.
They call for further research into the long-term relationship between vaccination and long-COVID.
Ayoubkhani D, Bermingham C, Pouwels KB et al. Trajectory of long covid symptoms after covid-19 vaccination: community based cohort study. *BMJ* 19 May 2022; doi: 10.1136/bmj 2021 069676
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