Studies suggest vaccines cut long COVID symptoms

Two recent studies suggest vaccinated people are significantly less likely to have symptoms associated with ‘long COVID’ after being infected with SARS-CoV-2.
 
An Israeli article published on MedRvix found those who had two vaccine doses reported fewer symptoms most closely linked with long COVID after infection compared with their unvaccinated counterparts.
 
The article has not yet been peer reviewed.
 
The researchers sent participating adults over the age of 18, all of whom had taken a PCR-test at three Israeli hospitals between March 2020 and November 2021, an online questionnaire. It included queries about demographics and whether participants were showing any symptoms linked with long COVID.
 
The study, which took place before the emergence of the Omicron variant, included the responses of 951 people confirmed with COVID-19, of whom 67% were double-dose vaccinated, while 2437 were uninfected with COVID-19 during the study period.
 
Binomial regression was used to compare self-reported symptoms in vaccinated and unvaccinated people after COVID-19 infection, as well as comparing the results to symptoms reported by those who had not been infected.
 
The researchers cited the most commonly reported long-COVID symptoms as fatigue, headache, weakness and persistent muscle pain.
 
Having two vaccination doses reduced reports of those symptoms after a positive PCR test by 64%, 54%, 57% and 68% respectively.
 
‘Those who received two doses were no more likely to report any of these symptoms than individuals reporting no previous SARS-CoV-2 infection,’ the article reads.
 
The researchers suggested the findings are a positive sign for those with breakthrough COVID-19 infections who have been vaccinated with Pfizer, the vaccine predominately used in Israel.
 
‘Vaccination with at least two doses of COVID-19 vaccine was associated with a substantial decrease in reporting the most common post-acute COVID-19 symptoms, bringing it back to baseline,’ they concluded.
 
‘Our results suggest that, in addition to reducing the risk of acute illness, COVID-19 vaccination may have a protective effect against long COVID.’
 
Among the study’s limitations is that it was unable to specify whether participants had been infected with SARS-Cov-2 before or after vaccination, with the authors suggesting more study is needed.
 
‘The effect of vaccination on long-term sequelae according to the infection/vaccination sequence warrants further research,’ they wrote.
 
There were 85 participants hospitalised with COVID-19 infection, leading researchers to say the study reflected the ‘mild end of the spectrum’ and that results should not be extrapolated for those who become severely ill.
 
The report also indicates COVID-19 vaccination seems to offer more protection against long-term symptoms in those aged over 60, which the authors acknowledge contradicts the findings of other studies.
 
‘Our analysis does not allow us to establish why the beneficial effect of the COVID-19 vaccine on long-term symptoms seems to be stronger in older age groups,’ they write.
 
‘A plausible explanation for the association found in the older individuals could be that younger individuals have more physiological reserve and are therefore able to recover on their own, which is not the case in older adults.’
 
Dr Soumya Swaminathan, the Chief Scientist at the World Health Organization (WHO), shared a report of the study in Nature magazine on social media saying it backed up data from the UK suggesting vaccination shielded people from long COVID.
 
The WHO formally recognised long COVID in October last year.
 
This month, the UK’s Office for National Statistics (ONS) also released figures showing a similar pattern to the Israeli study.
 
Using data from the UK’s Coronavirus Infection Survey (CIS), analysts found that being double-dose-vaccinated cut the chances of self-reported long COVID 12 weeks after infection by 41.1%.
 
The reduction is relative to study participants with a similar socio-demographic profile who were unvaccinated when infected.
 
The sample included adults aged 18–69 and considers those who reported COVID-19 infection at least two weeks after vaccination.
 
The analysis involved 6180 CIS participants who tested positive for COVID-19 for the first time between April 2020 and November 2021.
 
Participants were asked whether they would describe themselves as having symptoms more than four weeks after contracting COVID-19 that were ‘not explained by something else’.
 
The results showed ‘long COVID symptoms’ of any severity were reported by 9.5% of double-vaccinated participants and 14.6% of unvaccinated people.
 
A similar pattern was found for long COVID symptoms that limited day-to-day activities, a situation described by 5.5% of vaccinated participants and 8.7% of unvaccinated.

Researchers again included the caveat that it is still too early to understand the impact of the current variant of concern Omicron on long COVID, as well as the effect of third doses.
 
‘Longer follow-up time is needed to assess the impact of booster doses and the Omicron variant; furthermore, the observational nature of the analysis means that we cannot say whether COVID-19 vaccination caused subsequent changes in the likelihood of self-reported long COVID,’ the ONS release reads.
 
The ONS researchers say the data offers ‘no statistical evidence’ of any difference between vaccine types and the likelihood of reporting long COVID symptoms.

Log in below to join the conversation.
 

long COVID Omicron