Jan. 25 (UPI) -- Contracting COVID-19 after becoming fully vaccinated and or becoming vaccinated after being sickened with the virus provide strong immunity against future infection, a study published Tuesday by the journal Science Immunology found.
Both provide roughly equal levels of enhanced immune protection dubbed "super immunity" that is 10 times more potent than vaccination alone, the researchers said.
However, while they caution against intentional exposure to the virus to develop super immunity, they believe each new "breakthrough infection," or case that occurs in a fully vaccinated person, brings the pandemic closer to an end, they said.
Due to the highly contagious Omicron variant of the virus in circulation, "I would expect at this point many vaccinated people are going to wind up with breakthrough infections," study co-author Dr. Bill Messer said in a press release.
"Hence," they would develop "a form of hybrid immunity," said Messer, assistant professor of molecular microbiology and immunology and medicine (infectious diseases) in the Oregon Health and Science University School of Medicine in Portland.
With the release of the COVID-19 vaccines from Johnson & Johnson, Moderna and Pfizer-BioNTech last year, breakthrough infections were rare.
However, that was before the emergence of the Omicron variant in November, as the vaccines are less effective against the new strain, though they still protect against severe illness after infection.
For this study, researchers recruited 104 Oregon Health and Science University employees who were fully vaccinated with the Pfizer-BioNTech shot.
Participants were divided into three groups: 42 who were vaccinated with no infection, 31 who were vaccinated after an infection and 31 who had breakthrough infections after vaccination, the researchers said.
The researchers collected blood samples from each participant and exposed the samples to three COVID-19 variants, they said.
Both of the groups with "hybrid immunity," or vaccination plus infection, generated greater levels of immunity compared with the group that was vaccinated, but had no infection, the data showed.
"It makes no difference whether you get infected-and-then-vaccinated, or if you get vaccinated-and-then-a-breakthrough infection," study co-author Fikadu Tafesse said.
"In either case, you will get a really, really robust immune response," said Tafesse, assistant professor of molecular microbiology and immunology in the Oregon Health and Science University School of Medicine.
This study was conducted before Omicron began to circulate in the United States -- still, the researchers said they expect the hybrid or super immune responses would be similar with the new highly transmissible variant.
That's because, over time, the virus will run into an ever-expanding pool of human immunity, according to the researchers.
However, those sickened with Omicron who are not fully vaccinated will not develop high levels of immunity, the researchers said.
"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," he said.