Immunity

Shane Crotty, an immunologist, considers "hybrid immunity"; or "superhuman immunity" or "bulletproof as coined by other scientists, to be impressively potent against SARS-CoV-2. Whatever might be the name, this type of immunity brings a ray of hope amidst the COVID-19 crisis.

Recent researches have found an extraordinarily powerful immune response against SARS-CoV-2, in some people, by producing very high levels of antibodies with great flexibility. These antibodies have the capacity to fight off the prevailing as well as future emerging coronavirus variants.

Paul Bieniasz, a virologist at Rockefeller University, says that these people might be quite well protected against all or most of the SARS-CoV-2 variants that may emerge in future. Bieniasz and his colleagues, in a study, found antibodies in individuals with hybrid immunity that have the potential of strongly neutralizing the six variants of concern tested [delta, beta, and several other viruses related to SARS-CoV-2, including one in bats, two in pangolins and the one responsible for first coronavirus pandemic, SARS-CoV-1].

They also shared the probability of these individuals having some degree of protection against the SARS-like viruses that are yet to infect humans.

This "superhuman" or "hybrid" immune response can develop in individuals having a "hybrid" exposure to the virus, specifically, people with prior infection with the coronavirus in 2020, followed by immunization with mRNA vaccines. 

Theodora Hatziioannou, a virologist at Rockefeller University, considers these people to have amazing responses to the vaccine and be in the best position to fight the virus. He further explained these antibodies to have the potential to even neutralize SARS-CoV-1, the first coronavirus, which emerged 20 years ago, which is very different from SARS-CoV-2.

These antibodies even showed the potential to deactivate an engineered virus, highly resistant to neutralization. This virus suffered 20 mutations that can prevent SARS-CoV-2 antibodies from binding to it. Antibodies from people who were only vaccinated or priorly coronavirus infected persons (non-vaccinated) could not fight against this mutant virus. But antibodies of people with the "hybrid immunity" neutralized it, proving the strength of mRNA vaccines in people with prior exposure to SARS-CoV-2.

Another study, published in The New England Journal of Medicine, supports this hypothesis. In this study, the researchers’ analyzed antibodies of people priorly infected with the original SARS virus -SARS-CoV-1 (back in 2002 or 2003) and who then received an mRNA vaccine this year. Interestingly, these people too demonstrated a high level of antibodies that could neutralize a whole range of variants and SARS-like viruses.

What for people who arent infected with SARS-CoV-2 to date?

John Wherry, an Immunologist at the University of Pennsylvania, stated that they can see some of this antibody evolution happening in people who are just vaccinated, although it is faster in people who have been infected.

A recent study by Wherry et al. published online in late August showed that over time, people with two doses of the vaccine (and no prior infection) produce more flexible antibodies that can better recognize many of the variants of concern. Thus a third dose of the vaccine can give a boost and push the evolution of the antibodies further.