Previous COVID-19 Infection Gives Double Vaccinated Individuals Higher Rate of Protection

Priscilla Lynch 

October 08, 2021

Previous COVID-19 infection together with being double vaccinated, increases an individual’s protection against COVID-19 to as much as 94%, according to the latest analysis from the ZOE COVID Study, which investigates real-world vaccine effectiveness.

The study found that two doses of the AstraZeneca COVID-19 vaccine provided 71% protection against infection up to 6 months after vaccination, while protection was increased to 90% among those who previously tested positive for COVID-19.

Two doses of the Pfizer-BioNTech mRNA COVID-19 vaccine gave 80% protection up to six months after vaccination, which increased even further to 94% with a previous COVID-19 infection.

The analysis found that a previous COVID-19 infection without vaccination gave only 65% protection.

The research also found that the protection from a previous COVID-19 infection alone did not wane for up to 450 days after being infected, which was independent of vaccination status. This is unlike vaccine-only protection, which ZOE has observed probably begins to wane after 3 months.

Prof Tim Spector, the 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 double vaccination does mean greater protection. 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. This is also strong evidence to support the need for vaccination, even for those who have already had COVID-19. 

“When it comes to a booster jab, it’s my opinion that if you’re not in one of the eligible groups for a booster yet, but have a previous infection and two vaccines, you shouldn’t be too worried as your protection will be very high. It’s likely that there will be high levels of uptake in those who are double vaccinated and are invited for a booster, so it’s more important we focus on those who remain unvaccinated, which is still too high, and we are quickly falling behind the rest of Europe.”

Young People

Separate data from the ZOE study found that the number of daily new UK COVID-19 cases continues to increase rapidly in the under-19s, with an estimated one in 30 children aged between 10-19 years currently have COVID-19. Cases are also rising in the 30-49 age group, but at a slower rate, while cases of COVID-19 remain low and stable in contributors over the age of 50.

In total, there are currently 66,033 new daily symptomatic cases of COVID-19 in the UK on average, based on PCR and lateral flow test (LFT) data from up to October 2. This represents an increase of 13.6% from 58,126 new daily cases last week. 

In the double vaccinated population, it is estimated there are currently 16,901 new daily symptomatic cases in the UK, continuing a slow rise in recent weeks, with 14,352 cases last week.

This article originally appeared on Univadis, part of the Medscape Professional Network.


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