People aged 18 to 69 who had received a first dose were 12.8 per cent less likely to report that they were still experiencing persistent symptoms, according to experimental findings published by the Office for National Statistics (ONS).
A first vaccine dose appears to alleviate symptoms in long Covid sufferers, a new study has suggested, although it is unclear whether this improvement lasts until a second dose.
A second dose was associated with a further 8.8 per cent drop, with “statistical evidence” of a sustained improvement afterwards.
Because the study is based on a survey of self-reported symptoms, the ONS was unable to say for certain that vaccines affect the chances of getting long Covid.
The data is not clear on whether an initial improvement in symptoms after a first dose is sustained over time until a second dose, while long-term associations between a vaccine and long Covid “remain unknown”.
Long Covid is defined as symptoms that persist for at least 12 weeks after first having Covid-19.
The ONS used self-reported instances of long Covid between 3 February and 5 September.
Daniel Ayoubkhani, ONS head of health modelling, said: “Today’s study, the largest internationally to look at long Covid after vaccination, shows that the likelihood of ongoing symptoms is reduced after vaccination.
“But we can’t say for certain whether vaccination caused the observed changes, and it remains unknown as to whether these will be sustained in the long term.”
The ONS found no statistical evidence of differences in self-reported long Covid between people who received AstraZeneca, Pfizer or Moderna vaccines.
There was also no evidence of differences in trends based on social or demographic characteristics – such as age, gender and ethnicity – or from health-related factors such as whether someone had previously been admitted to hospital with acute Covid-19.
Commenting on the study, Dr Fergus Hamilton, an honorary research fellow at the University of Bristol, said: “This research is very reassuring to people who are suffering with prolonged symptoms after Covid-19.
“As shown in previous research, there does appear to be a observed benefit of vaccination in reducing symptom burden in patients who have been previously infected. This has now been shown in multiple cohorts, and suggests that the observed finding is likely true.
“The major questions – which are hard to unpick from research like this – is whether the association is causal, and what the mechanism of the association might be.”
A previous study from King’s College London suggested that being fully vaccinated cuts the risk of an infection turning into long Covid.
It showed that in the minority of people who catch Covid, despite receiving two doses, the odds of developing symptoms lasting longer than four weeks are cut by 50 per cent. This is compared with people who are not vaccinated.
