Researchers said that after a previous infection with “Covid-19” and two doses of the “Pfizer” or “Moderna” vaccine, some people’s immune systems developed an amazing ability to respond to variants of the virus.
Researchers call this “super-immunity” or “hybrid immunity” – these patients’ immune systems can produce a lot of antibodies capable of responding to different variants, as documented in multiple studies in recent months.
In one study, patients with this “hybrid immunity” showed the ability to respond to current variants of concern, non-human coronaviruses, and perhaps even new variants that did not yet exist.
Scientists are studying these patients to better understand Covid immunity – and immunity to other viruses.
The “Pfizer” and “Moderna” vaccines work by providing the immune system with a piece of genetic material from the Corona virus – a piece of messenger RNA – that teaches the immune system to recognize the virus in case of infection.
With both an mRNA vaccine and a previous infection with Covid-19, patients may become highly immune to the disease.
Recent studies have shown that vaccinated and infected people show “supernatural” immunity, as some scientists have called it.
Theodora Hatziwano, a Rockefeller University virologist who has studied these patients, told NPR: “These people have amazing responses to the vaccine. I think they are in the best position to fight the virus.”
And the antibodies in the blood of these people can neutralize SARS-CoV-1, the first coronavirus, which emerged 20 years ago. “This virus is very different from SARS-CoV-2,” Hatziwano said.
Immunologist Shane Crotty explained, in a June 2021 commentary article for Science, “natural immunity” from a previous infection works differently from immunity from vaccination.
In natural immunity, the immune system will build various means of protection against the future invasion of the Corona virus.
This includes B cells and T cells, both of which remember the shape of the virus and can stimulate antibody production in the event of another infection.
Studies have found that natural immunity will usually last for seven to eight months. After about a year, the immune system will still retain some memory but may be more susceptible to changes.
If a person with natural immunity is vaccinated, the vaccination enhances the immune system’s memory of the Corona virus.
Crotty explains that the immune system handles any new exposure – whether it’s an infection or a vaccination – with a cost-benefit analysis of the volume of immune memory to be generated and maintained.
As a result, when a person is vaccinated after recovering from Covid, the vaccine acts as a signal to the immune system that this virus is a serious problem – and the immune system should devote more resources to protecting against it.
That means more B cells and T cells that remember what the coronavirus looks like — including B cells that are already trying to predict potential new viral variants.
Crotty calls these protective guesses of memory B cells by the immune system regarding viral variants that may emerge in the future.
T cells also help protect against future variants, as aspects of the virus that T cells recognize are unlikely to change as the virus mutates.
In one study that Crotty cited, researchers found that individuals who had previously been infected and had received the vaccination developed 100 times more protective antibodies against the B.1.351 variant compared to those who had only been infected.
These individuals had immune systems better prepared to fight the variant, even though they had not previously had this type.
Scientists have observed such a high level of immunity against the Corona virus in both people who have had severe “Covid” cases, and those who have mild symptoms or no symptoms at all.
A recent study by researchers at Rockefeller University — published online as a preliminary publication in August — demonstrated the power of hybrid immunity.
The researchers analyzed the immune system readiness of 15 patients previously infected with “Covid” who were subsequently vaccinated – compared to patients who were vaccinated only or infected only.
They tested blood plasma samples from “hybrid immune” patients against six different types of coronavirus, the original SARS virus, and coronaviruses found in bats and pangolins.
For all of these different variants, the “hybrid immune” patients’ immune systems were able to recognize the invaders and build up antibodies to fight them.
Researchers have even tested a new type of coronavirus, developed in the lab, that is specifically designed to withstand detection by the immune system. And these immune systems can still fight it.
“One could reasonably predict that these people would be well protected against most – and possibly all – SARS-CoV-2 variants that we are likely to see in the foreseeable future,” said Paul Peñas, a virologist at Rockefeller University and the study leader. But I also doubt that they have some degree of protection against SARS-like viruses that have not yet infected humans.”
This study, like others that have explored hybrid immunity, was small – and the researchers aren’t sure whether everyone who was vaccinated after infection would have the same immune response.
But it’s notable that all of the patients in this study had the same highly successful response to the various coronavirus variants, Hatziwano told NPR.
And immunologists plan to bring coronavirus immunity closer together, to develop more successful vaccines against this disease and others.