The natural immune protection that develops after a SARS-CoV-2 infection offers considerably more of a shield against the Delta variant of the pandemic coronavirus than two doses of the Pfizer-BioNTech vaccine, according to a large Israeli study. The newly released data show people who once had a SARS-CoV-2 infection were much less likely than vaccinated people to get Delta, develop symptoms from it, or become hospitalized with serious COVID-19. The study shows that double vaccinated people were six to 13 times more likely to get infected than unvaccinated people who were previously infected with the coronavirus. The study demonstrates the power of the human immune system.
The researchers also found that people who had SARS-CoV-2 previously were more highly protected against reinfection than those who were vaccinated.
The new work (read below) could inform discussion of whether previously infected people need to receive both doses of the Pfizer-BioNTech vaccine or the similar mRNA vaccine from Moderna.
Vaccine mandates don’t necessarily exempt those who had a SARS-CoV-2 infection already and the current recommendation is that they be fully vaccinated, which means two mRNA doses or one of the J&J adenovirus-based vaccine.
The study (read below), conducted in one of the most highly COVID-19–vaccinated countries in the world, examined medical records of tens of thousands of Israelis, charting their infections, symptoms, and hospitalizations between 1 June and 14 August, when the Delta variant predominated in Israel.
It’s the largest real-world observational study so far to compare natural and vaccine-induced immunity to SARS-CoV-2, according to its leaders.
The massive surge of COVID-19 infections in Israel, one of the most vaccinated countries on earth, is nothing less than a disaster. The Israel vaccine crisis should be a warning to the rest of the world.
The research impresses Nussenzweig and other scientists who have reviewed a preprint of the results, on medRxiv. “It’s a textbook example of how natural immunity is really better than vaccination,” says Charlotte Thålin, a physician and immunology researcher at Danderyd Hospital and the Karolinska Institute who studies the immune responses to SARS-CoV-2.
“To my knowledge, it’s the first time [this] has really been shown in the context of COVID-19.”
The study shows the benefits of natural immunity, but “doesn’t take into account what this virus does to the body to get to that point,” says Marion Pepper, an immunologist at the University of Washington, Seattle