One dose of AstraZeneca’s COVID-19 vaccine generates equal amounts of antibodies as two doses of Pfizer/BioNTech’s mRNA vaccine if the person has previously had COVID-19.
These are the findings from a co-study of the COMMUNITY study at Danderyd’s Hospital that investigates immunity after COVID-19. During the spring of 2020 samples from 2,149 co-workers at Danderyd’s Hospital were collected, and around 19% of them were shown to have antibodies against SARS-CoV-2. The participants and their immune responses have since then been monitored every forth month. During the spring of 2021 a great number of the participants were vaccinated against COVID-19. Some of them were vaccinated with Pfizer/BioNTech’s mRNA vaccine Comirnaty and some of them were vaccinated with AstraZeneca’s vaccine Vaxzevria.
“Studies have shown that an mRNA vaccine provides a quick and strong immune response in an individual that has previously had COVID-19. This is expected since a natural infection works like a so called primer and the vaccination as a booster for the immune defense. So far there has not been any data showing how a dose of AstraZeneca’s vaccine affects the immune defense in someone who has undergone an infection. Our results now show that one dose of AstraZeneca’s vaccine to a person that has previously had a COVID-19 infection provides a strong antibody defense against the regular SARS-CoV-2 variant – but also against virus variants of particular importance first detected in the UK, South Africa and Brazil,” says Charlotte Thålin, responsible scientist for the COMMUNITY study at Danderyd’s hospital and Karolinska Institutet. “The level of antibodies observed in a person that has previously been infected with COVID-19 and thereafter vaccinated with one dose of Vaxzevira is equally high or higher against all variants that we have tested. This was also true for participants that had COVID-19 a year ago. This indicates that one dose might be enough if you previously have had COVID-19, even though it was a long time ago.”
Photo of Charlotte Thålin: Magnus Laupa