Covid vaccination reduces the risk of developing long Covid, while current sufferers may experience an improvement in symptoms after getting jabbed, a comprehensive review by the UK Health Security Agency suggests.
The “rapid evidence briefing” drew together data from 15 UK and international studies, about half of which examined whether Covid vaccination protected against developing long Covid if someone had never been infected, while the rest looked at the impact of vaccination among people who already had long Covid.
It found that, as well as any benefit obtained by not catching the virus in the first place, those who do catch it are less likely to develop long Covid if they have received one or two doses of vaccine compared with unvaccinated individuals.
According to the two studies that measured individual long Covid symptoms, the fully vaccinated were less likely than unvaccinated people to develop medium- or long-term symptoms such as fatigue, headache, weakness in the arms and legs, persistent muscle pain, hair loss, dizziness, shortness of breath, loss of smell or scarring of the lungs.
“There is also evidence that unvaccinated people with long Covid who were subsequently vaccinated had, on average, reduced long Covid symptoms, or fewer long Covid symptoms than those who remained unvaccinated,” the review said.
There were, however, some people who reported worsened symptoms after vaccination, it added.
Deborah Dunn-Walters, chair of the British Society for Immunology Covid-19 taskforce and a professor of immunology at the University of Surrey, said there was not yet enough information to explain why vaccination should lead to an improvement in people’s symptoms. “The term ‘long Covid’ covers a wide range of post-Covid conditions and so we don’t yet fully understand all the processes involved,” she said.
One theory is that it may help clear up remaining reservoirs of virus in the body, or fragments of virus that are triggering ongoing inflammation. Another possibility is that vaccination rebalances the immune response in individuals whose symptoms are being driven by autoimmune-like processes – this may also explain why a few people report worse symptoms after vaccination, Dunn-Walters added.
She said: “This review re-emphasises the importance of everyone, no matter their age, getting vaccinated against Covid-19. Although there has been a high uptake of the vaccines in the UK so far, a significant number of people still need to come forward for a first or second dose. We must continue to make every effort to reach these people and encourage them to come forward for Covid-19 vaccination.”
Prof Stephen Powis, the national medical director of NHS England, said: “With more than 10,000 people in hospital with Covid [in the UK], this study is a timely and important reminder that vaccines remain our best protection against the virus, reducing the chances of becoming seriously unwell as well as the effects of long Covid.”