Previous COVID-19 Infection Plus Vaccine Defends Delta Variant Best
Publishing as a non-peer-reviewed preprint study on August 25, 2021, researchers led by Tal Patalon and Sivan Gazit at Maccabi Healthcare Services in Tel Aviv, Israel, analyzed a healthcare database containing information about 2.5 million Israelis.
They examined new SARS-CoV-2 betacoronavirus infections in people who had never been infected but had been vaccinated with the mRNA Comirnaty (Pfizer - BioNTech) vaccine, and those who were not yet vaccinated but had recovered from COVID-19, and in people who had received one dose of Comirnaty and had also previously had COVID-19.
These researchers found that Israelis who had never been infected and were vaccinated in January and February were 6-13 times more likely to become infected during June – August 2021, when the Delta variant was the dominant strain circulating in Israel unvaccinated people who had recovered from SARS-CoV-2.
They also compared two groups of 14,000 unvaccinated people who had recovered from SARS-CoV-2 with a similarly sized group of people who had previously been infected and had received one dose of the Comirnaty vaccine.
The research team found that the previously infected but unvaccinated group was 2x as likely to be reinfected as those previously infected and received one dose of the Comirnaty vaccine.
The study indicates that the natural immunity gained through becoming infected and recovering from SARS-CoV-2 is of great value in protecting against future disease.
Moreover, this protection is further enhanced when combined with COVID-19 vaccination.
'It’s important to note that although natural immunity can be highly protective, it can come at a great cost – millions haven’t survived COVID-19, and others have suffered severe disease and hospitalization, said GAVI in a statement issued on August 31, 2021.