Coronavirus vaccines reduce risk of long Covid, study suggests

·4 min read
 (AFP via Getty Images)
(AFP via Getty Images)

The risk of developing long Covid appears to be significantly reduced after vaccination, new research suggests.

In a study of more than 6,000 people, run by the Office for National Statistics, those who were double-jabbed with Pfizer or Moderna were 41 per cent less likely to report persistent symptoms 12 weeks after testing positive for Covid.

This figure dropped to 37.7 per cent for people vaccinated with doses of AstraZeneca.

Across the 6,180 people enrolled in the research, 9.5 per cent of the vaccinated group said they had experienced long Covid, compared with 14.6 per cent of a socio-demographically matched group who were unvaccinated.

The research did not assess the impact of boosters and was relevant up to 30 November, meaning it did not cover the subsequent Omicron wave.

Dr Claire Steves, a senior clinical lecturer at Kings College London, said the study “backs up findings we published last year, using a different dataset.”

She added: “It’s another reason for people to be vaccinated, as well as reducing risk of severe initial illness.

“However, this study reminds us that while substantially lessened, vaccination doesn’t completely get rid of the risk of long Covid entirely, so with numbers so high it’s still important that we search for treatment strategies and ensure people affected have the support they need.”

However, the ONS cautioned that it was unable to definitively say that vaccination causes a reduction in the risk of developing long Covid.

“That’s because this is an observational study,” said Kevin McConway, emeritus professor of applied statistics at the Open University.

“People weren’t allocated at random to be vaccinated or not – they did what they would have done anyway, regardless of the survey. Therefore there will be many differences between the vaccinated and the unvaccinated people, apart from the simple fact of vaccination.

“Any combination of these other differences could be the real cause of the differences in the chance of long Covid, in whole or in part, and not the vaccination at all.”

However, he said, “I think these results do provide quite a big measure of indicative evidence that double vaccination might well cause a reduction in the risk of long Covid, if one is unlucky enough to become infected after being vaccinated.”

According to the latest ONS estimates, some 1.3 million people in the UK have long Covid - defined as symptoms lasting more than 12 weeks.

Separate analysis from the ONS shows that lower vaccination take-up among some ethnic groups contributes to an increased risk of Covid-19 death, particularly for people from black African and Caribbean backgrounds.

Most ethnic minority groups have continued to experience greater rates of death involving Covid-19 during the third wave of the virus compared with people identifying as white British.

These differences have been attributed mostly to social and demographic factors, such as geography, type of residence and health.

But levels of vaccination coverage are now contributing to the elevated risk of death observed in some groups, according to the ONS.

It is the first time vaccination take-up has been linked in this way with estimates of mortality rates. Between 13 June and 1 December 2021, the risk of death involving Covid-19 for black African males in England was 1.4 times greater than that for white British males, after adjusting for age, demographic factors and certain pre-existing conditions.

But after also adjusting for vaccination status - to reflect if someone has received a first, second or third dose - this difference was found to have been eliminated.

A similar pattern was evident for black Caribbean males, with the risk 1.7 times greater before adjusting for vaccination status, but no excess risk after.

For black African and Caribbean females, the risk of Covid-19 death before adjusting for vaccination was estimated at 1.8 and 2.1 times greater than white British females respectively - but again, this excess risk disappeared after accounting for vaccine take-up.

The figures suggest that, once adjusted for vaccination status, there is "no evidence" that the risk of death involving Covid-19 is greater for people from these ethnic groups than for the white British ethnic group, the ONS said.

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