Previous COVID-19 infection protects against Delta better than Pfizer shot: Report

People who were previously infected with COVID-19 are reportedly better protected from the highly contagious Delta variant when compared to those without previous infections and who have received the Pfizer-BioNTech COVID-19 vaccine, according to research shared on medical journal medRxiv.

The study, which was completed by researchers in Israel — one of the most highly vaccinated countries in the world — has not yet been peer-reviewed.

What are the details?

People who recovered from a bout with COVID-19 may face lower risk from the Delta variant when compared to those who have not been infected with coronavirus at all and have just the two-dose Pfizer vaccine, Bloomberg reported.

According to a Friday report from Science magazine's Meredith Wadman, "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 that some scientists wish came with a 'Don't try this at home' label."

Researchers' findings argue that people who received both doses of the Pfizer vaccine and who had not previously contracted COVID-19 were 13 times likelier to contract the highly transmissible Delta variant, compared to those who previously suffered an infection, when either the vaccination or the infection occurred in January or February 2021.

In those who were infected "at any time before vaccination (from March 2020 to February 2021), evidence of waning natural immunity was demonstrated"; however, people who had not had COVID-19 previously were still nearly six times likelier get a breakthrough case of the Delta variant and over seven times likelier to have symptomatic illness than those who had previously been infected.

Researchers concluded, "This study demonstrated that natural immunity confers longer lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity. Individuals who were both previously infected with SARS-CoV-2 and given a single dose of the vaccine gained additional protection against the Delta variant."

What are other experts saying about this?

Infectious diseases experts, however, warn that while the study is generally good news, all COVID-19 vaccines remain highly protective against "severe disease and death."

Michel Nussenzweig, immunologist at Rockefeller University, told Wadman, "What we don't want people to say is: 'All right, I should go out and get infected, I should have an infection party.' Because somebody could die."

Charlotte Thålin, a physician and immunology researcher at Danderyd Hospital and the Karolinska Institute, added, "It's a textbook example of how natural immunity is really better than vaccination. To my knowledge, it's the first time [this] has really been shown in the context of COVID-19."