Two doses of the Pfizer vaccine provided 95% protection against Covid in those who previously tested positive for the virus, a study found.

Researchers at King’s College London analysed data from more than a million regular UK contributors to the ZOE Covid study app, which allows people to log their vaccination status and test results along with daily health reports.

They defined six groups of people, according to whether they were double vaccinated with either the Pfizer or AstraZeneca vaccines or were unvaccinated, and whether they had previously tested positive for Covid-19.

They then looked at how many people in each of these groups reported testing for positive the virus during the UK Delta wave from May to June 2021, and calculated their level of protection.

READ MORE: Covid in Scotland: Schools set for big step closer to normality 

Researchers found that two doses of the AstraZeneca vaccine gave 71% protection against infection, increasing to 90% for people who had previously tested positive for Covid.

Two doses of the Pfizer vaccine provided 87% protection, which went up to 95% for people who had already been infected with the virus.

By contrast, having Covid without being vaccinated only gave 65% protection against catching it again.

Researchers found that among those who were infected in the first wave of the pandemic in Spring 2020, protection from a previous infection didn’t wane, up to 450 days later, independent of whether the person was vaccinated or not. 

Professor Tim Spector, lead scientist on the ZOE Covid Study app, said:  “Regardless of which vaccine is administered, this latest research shows that having a natural Covid-19 infection before being fully vaccinated does mean greater protection.

READ MORE: Where can I go on holiday? Countries that are still on the Covid red list 

"This is really positive news for overall immunity levels in the UK, and means that large numbers of people will have effective and long lasting protection from Covid-19."

Prof Spector said those who have had the virus and two vaccines would still have a very high level of protection.

He said: "If you’re not yet eligible for a booster, but have had a previous infection and two vaccines, I wouldn't be too worried as your protection will be very high.

"It’s important we focus on the number of high-risk people who remain unvaccinated, which is still too high, as we fall behind the rest of Europe, slowing our progress in reducing rates of infection and bringing the pandemic to an end.”