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Two studies published in BMJ Medicine look at COVID-19 vaccination and long COVID.
Dr Catherine Hyams, PostDoctoral Clinical Research Fellow and Respiratory Specialist, University of Bristol, said:
“It is always challenging to provide robust real-world evidence of the effect of vaccines, never more so than in a pandemic and its aftermath – it is even more difficult when trying to evaluate a condition like long COVID which is new, has a wide range of symptoms and can fluctuate over time. Tran and colleagues adapted an ongoing study to provide evidence as to whether COVID19 vaccines reduce the severity of long COVID. It’s important to recognise that there are limitations to this study – small patient numbers, and an adapted methodology. They found COVID19 vaccines given after COVID19 infection cause a small reduction in patient symptoms and importantly show that vaccinated patients with long COVID reported that their quality of life was better than patients with long COVID who were not vaccinated. This suggests that COVID vaccination does improve the quality of life in patients with long COVID, even if the vaccine is given after the patient has long COVID.
“The evidence from this study is supported by another analysis of all the available evidence on this subject. Byambasuren and colleagues reviewed evidence from 164,392 patients across 16 studies, effectively pooling the results, although only 12 studies included evidence about vaccination before infection with COVID. The researchers found that having one dose of COVID vaccine before infection probably does not reduce the risk of long COVID, but the evidence is more suggestive that two or more doses is likely to be beneficial. However, there are really substantial differences between the way all the reviewed studies were conducted and a risk of bias in the analysis, making it difficult to be certain that this evidence is completely accurate.
“COVID19 vaccines are safe, have a very low risk of side-effects and have been shown to significantly reduce the risk of death, severe COVID19 disease and complications from COVID19 infection. These studies provide encouraging evidence that COVID19 vaccines are likely to have some effect on reducing the risk of developing long COVID and may even reduce the severity or length of long COVID when given after someone has developed this condition. This additional benefit of COVID19 vaccines should not be ignored and, although we need more evidence in the case of long COVID, if there is additional therapeutic benefit to using COVID19 vaccines, then we should be harnessing this to improve patient outcomes and the quality of their lives.
“It may well not be possible to conduct trials comparing COVID19 vaccine versus placebo (per WHO protocol) on COVID19 vaccine effectiveness against long COVID, but well-conducted and standardised real-world studies can be just as powerful and in fact often provide evidence which randomised controlled trials cannot. As COVID19 and resultant long COVID remains a significant worldwide problem, it is therefore vital that well-conducted real-world studies are undertaken to address this question.”
Prof Sir Andrew Pollard, Director of the Oxford Vaccine Group and Ashall Professor of Infection and Immunity, University of Oxford, said:
“This observational study of the effect of vaccination against COVID19 on long COVID symptoms suggests a small reduction in symptom scores among those who were vaccinated when compared with controls. Because long COVID includes such a varied group of symptoms it is unclear from this study who might benefit or whether these differences are clinically important in the long run. The authors rightly point out the potential for bias in observational studies because the people in the vaccinated and unvaccinated groups are not randomly selected from the population and have made different decisions about immunisation. There might be a placebo effect as those who got vaccinated may have believed they would feel better. Nevertheless, such studies provide evidence that should drive further investigation into whether vaccination helps and, if so, who will benefit, and we should address the biological plausibility question by evaluating the “why”. For patients who have long COVID, it would seem sensible to be vaccinated in case these effects are real, but it would be better to do so as part of a randomised controlled trial so that we have a more definitive answer.”
‘Efficacy of first dose of covid-19 vaccine versus no vaccination on symptoms of patients with long covid: target trial emulation based on ComPaRe e-cohort’ by Viet-Thi Tran et al. and ‘Effect of covid-19 vaccination on long covid: systematic review’ by Oyungerel Byambasuren et al. were published in BMJ Medicine at 23:30 UK time on Tuesday 28 February.
DOI: 10.1136/bmjmed-2022-000229
DOI: 10.1136/bmjmed-2022-000385
Declared interests
Dr. Catherine Hyams is the Principal Investigator of the AvonCAP study and a Co-Investigator of the AvonCAP GP2 study. AvonCAP evaluates the effectiveness of COVID-19 vaccines against severe disease in hospitalised patients (publishing results to this effect), and is an investigator-led study from the University of Bristol which is funded through a collaborative agreement by Pfizer Inc. Dr Hyams is also a member of the UKHSA COVID-19 Vaccine Effectiveness (VE) Working Group.
Prof Sir Andrew Pollard: “This comment is made in a personal capacity. Andrew Pollard is chair of the UK Department of Health and Social Care’s (DHSC) Joint Committee on Vaccination and Immunisation (JCVI), but does not chair or participate in the JCVI coronavirus committee, and was a member of the World Health Organization’s (WHO) Strategic Advisory Group of Experts until the beginning of 2022. He has received research funding for coronavirus vaccine research from UKRI, CEPI and NIHR. Oxford University has entered into a partnership with Astra Zeneca for the development of a coronavirus vaccine.”