Prior Covid Infection Is As Effective At Preventing The Virus As Vaccination, U.K. Study Suggests

According to new research published Monday, people who have had Covid-19 in the past are protected against the disease.

CREMONA (ITALY) - JANUARY 6: A doctor prepares the Pfizer BioNTech Covid-19 vaccine at Cremona Hospital, Cremona, Italy on January 6, 2021. To be ready to inject, Pfizer's vaccine must be dilute and placed in single syringes. Each vial can contain 6 doses of vaccine. (Photo by Marco Mantovani/Getty Images). Getty Images

The Key Facts

The U.K.'s Office of National Statistics (ONS), published a study that examined more than 8,000 coronavirus positive tests in Britain between May to August. Delta was the predominant variant. The analysis showed that people who had recovered from Covid-19 were 71% less likely than those who did not. The study found that the two doses of vaccines AstraZeneca and Pfizer provided the same protection as the previous inoculation drives in Europe. The risk of contracting Covid-19 was reduced by 73% with two doses of Pfizer vaccine, compared to 62% with AstraZenecas vaccine. Researchers concluded that there was no evidence to suggest that full vaccination is more effective than natural infection in preventing Covid-19. Although the study was not peer-reviewed, it found that previous infection was equally effective in preventing symptoms of Covid-19. However, it did not examine the differences between vaccines and natural infection in preventing severe diseases.

Important Background

Numerous studies have been conducted on natural immunity. Many of these studies came up with different results. According to an Israeli study, people who received two vaccinations had six times the chance of contracting the delta variant of Covid-19 than those who had not had them. The study found that people who had been vaccinated were at a greater risk for symptomatic infections and had a 6.7-fold increase in the likelihood of being admitted to hospital. Other studies show that mRNA vaccines are more effective than Covid-19 in producing antibodies. Scientists recommend that anyone who has been infected with Covid-19 be vaccinated. This is despite the fact that there are many questions remaining about natural immunity, how it works, and how long it lasts.

Important Quote

Research has consistently shown that a second vaccine can increase immunity levels by combining an existing infection with the previous one. Sarah Croft (head of analysis for the U.K. Study) highlighted that those who have had a previous infection and received two vaccines were most protected.


Both vaccines proved less effective in preventing Covid-19 when the virus was in its delta wave than they were during the alpha wave. The effectiveness of two doses Pfizer vaccine were 80% in the earlier period, while 76% was for AstraZenecas vaccine. Croft suggested that this trend could be an indication of waning immunity to vaccines, as the data also includes participants who have had a longer average period of time since their second Covid vaccination.

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