THE risk of long covid may be lower in people who catch the coronavirus after being vaccinated.
Daniel Ayoubkhani at the UK's Office for National Statistics (ONS) and his colleagues looked at a random sample of people, aged 19 to 69, who tested positive for the coronavirus between April 2020 and November 2021. The sample included 3090 people who had received a second dose of either the Pfizer/BioNTech, Moderna or Oxford/AstraZeneca coronavirus vaccine at least two weeks before they first tested positive.
These participants were paired up with a random sample of 3090 unvaccinated people, with the individuals being matched by their age, sex, socioeconomic status, any pre-existing health conditions and whether they were white or a different ethnicity. The sample size was too small to group the participants according to more specific individual ethnicities, says co-author Vahé Nafilyan. All the participants were part of the UK Covid-19 Infection Survey.
Long covid was defined as any symptom the participants self-reported 12 weeks after testing positive that they could only put down to the coronavirus.
Of the unvaccinated participants, 14.6 per cent reported having at least one long covid symptom, compared with 9.5 per cent of those who were vaccinated. Vaccines were linked with a 41 per cent lower risk of long covid at 12 weeks (Open Forum Infectious Diseases, doi.org/jd6x). The longer-term risk wasn't explored.
Coronavirus vaccines were linked with a 41 per cent lower risk of long covid at 12 weeks post-infection
According to Ayoubkhani, a major limitation of the study is that most of the vaccinated participants were infected when the delta variant was dominant, whereas most of the unvaccinated people probably caught the alpha variant.
The question is now less about if vaccination reduces long-term symptoms, but why and how much, says Michael Edelstein at Bar Ilan University in Israel.