Covid vaccine side effects up to three times more common in those who have had virus

Sarah Knapton
·3-min read
A health worker signals to a colleague that she is available to administer a vaccine at a mass Covid vaccination centre in Barry, South Wales - Matthew Horwood/Getty Images Europe
A health worker signals to a colleague that she is available to administer a vaccine at a mass Covid vaccination centre in Barry, South Wales - Matthew Horwood/Getty Images Europe

Vaccine side effects are seen up to three times more often in people who have previously been infected with coronavirus, new figures show.

The latest data from the King's College ZOE app, which has logged details from more than 700,000 vaccinations, found those with a prior infection were far more likely to report side effects than people who have not had the virus.

The difference between the two was particularly pronounced among those who had been given the Pfizer jab.

More severe side effects are often a sign of better immunity, and emerging research suggests just one dose of vaccine gives a similar protective effect to two doses in people who have had a previous infection.

Experts have now started to question whether people with prior immunity from a natural infection need a second dose at all.

The ZOE data shows that 12.2 per cent of people reported side effects after their first Pfizer jab, but that jumped to 35.7 per cent of those with a previous infection.

For the Oxford/AstraZeneca jab, 31.9 per cent of people reported symptoms following their first vaccine, rising to 52.7 per cent of those who had previously been diagnosed with diagnosed with the virus. Most people reported muscle aches, feeling groggy or headaches.

Ellie Barnes, professor of hepatology and immunology at the University of Oxford and one of the Oxford vaccine team, said: "There's emerging data to show that when you've had a Covid infection your T-cells become activated, and then over the weeks after that they become memory T-cells and kind of calm down.

"But they are then able to respond very rapidly to subsequent vaccination. So if you've been infected before and then get your first dose of the vaccine, you have a really excellent response to that single dose compared to someone that wasn't infected before."

Last month, researchers from Mount Sinai Hospital, in New York, found that people with prior infection had between 10 and 20 times more antibodies after their first vaccination than those who had never had the virus. The authors said those with a previous infection would be unlikely to need a second dose and jab supplies could be diverted elsewhere.

The University of Maryland, in the US, also found a greater antibody response in healthcare workers who had previously been infected after vaccination.

Eleanor Riley, professor of immunology and infectious disease at the University of Edinburgh, said: "Both papers suggest that people who have had a PCR confirmed covid-19 infection may only require one dose of the vaccine.

"Certainly, this would appear to provide them with protection that is at least as good as two doses of vaccine. However, incorporating this into a mass vaccination programme may be logistically complex and it may be safer, overall, to ensure that everyone gets two doses."

Lawrence Young, a virologist and professor of molecular oncology, at the University of Warwick, said: "If future work can confirm this high level of immunity post a single mRNA vaccine in this group of individuals, this could become a viable option when there are concerns around vaccine supply."

The King's research showed that women were twice as likely as men to suffer side effects from the Pfizer jab and around 50 per cent more likely from the AstraZeneca vaccine.