More than one way to obtain robust COVID-19 immunity has been discovered, according to new laboratory research from the Oregon Health & Science University, published on Tuesday in the journal Science Immunology.
According to the study, two types of immunity: breakthrough infections after vaccination and natural infection followed by vaccination, produce essentially identical levels of immune protection.
"It makes no difference whether you get infected-and-then-vaccinated, or if you get vaccinated-and-then-a-breakthrough infection," co-senior author Fikadu Tafesse, Ph.D., assistant professor of molecular microbiology and immunology in the OHSU School of Medicine is quoted in EurekAlert's report as explaining the results. "In either case, you will get a really, really robust immune response – amazingly high."
Although the research was conducted before the discovery of the Omicron variant, experts believe that the hybrid immune responses will be comparable with the new highly transmissible strain.
According to EurekAlert, the new study builds on an OHSU research released in December that demonstrated exceptionally high levels of immune response in the aftermath of breakthrough infections, a phenomenon known as "super immunity."
That research was the first to detect cross-neutralization of blood serum from breakthrough patients using various live SARS-CoV-2 strains.
It does not matter whether someone gets a breakthrough illness or is vaccinated after a natural infection, according to the new study. Immune responses evaluated in blood serum in both cases indicated antibodies that were similarly plentiful and strong – at least 10 times more potent than immunity induced only by vaccination.
"The likelihood of getting breakthrough infections is high because there is so much virus around us right now," Tafesse said. "But we position ourselves better by getting vaccinated. And if the virus comes, we’ll get a milder case and end up with this super immunity."
For the research, scientists gathered a total of 104 people, all OHSU employees who were vaccinated with the Pfizer vaccine, and divided them into three groups: 42 people who were vaccinated without infection, 31 people who were vaccinated after an infection, and 31 people who developed breakthrough infections after vaccination.
The researchers took blood samples from each participant and exposed them to three forms of the live SARS-CoV-2 virus at a Biosafety Level 3 lab, controlling for age, sex, and time since vaccination and infection. They discovered that both groups with "hybrid immunity" produced higher levels of immunity than the group that was vaccinated but not infected.
Antibody levels following breakthrough infection, hybrid immunity, and vaccination alone.
© Photo : OHSU / SCIENCE IMMUNOLOGY
Moreover, the researchers believe that with the highly contagious Omicron variety spreading around the world, each new breakthrough infection could bring the pandemic closer to an end.
"I would expect at this point many vaccinated people are going to wind up with breakthrough infections – and hence a form of hybrid immunity," senior co-author Bill Messer, M.D., Ph.D., assistant professor of molecular microbiology and immunology and medicine (infectious diseases) at the OHSU School of Medicine said.
Nevertheless, the study authors said they have not studied numerous rounds of natural infection, but considering that billions of people around the world are still unvaccinated, many people will likely fall into that category.
And many unvaccinated people who have already been infected will most likely be infected again due to Omicron and other variants that are likely to come.
A previous study of the unvaccinated has revealed a considerably more variable amount of immune response than vaccination, according to Messer. In that study, the findings underscored the necessity of vaccination in conjunction with maintaining public health measures to stop the spread of COVID-19.
"I can guarantee that such immunity will be variable, with some people getting equivalent immunity to vaccination, but most will not," he said. "And there is no way, short of laboratory testing, to know who gets what immunity. Vaccination makes it much more likely to be assured of a good immune response."
The study's other senior co-author Marcel Curlin, M.D. told EurekAlert that natural infection alone has a varying level of immunity.
"Some people produce a strong response and others do not," he said. "But vaccination combined with immunity from infection almost always provides very strong responses."
He also expressed confidence that the novel coronavirus will be a relatively mild endemic sickness, similar to a seasonal respiratory tract infection, rather than a global pandemic.