According to new laboratory research led by Oregon Health & Science University (OHSU), breakthrough COVID-19 infections following vaccination, or natural infection followed by vaccination can lead to long-lasting “super immunity” to this disease. This is due to a greater abundance of antibodies that are at least ten times more potent than those generated by vaccination or infection alone.
The scientists recruited 104 OHSU employees who were vaccinated with the Pfizer BioNTech vaccine and divided them into three groups: 42 participants who were vaccinated but had not been infected, 31 who were vaccinated after an infection, and 31 who had breakthrough infections after vaccination. Blood samples from all of them were exposed to the Alpha, Beta, and Delta variants of the live SARS-CoV-2 virus in a laboratory at OHSU.
The findings suggest that people with “hybrid immunity” generated greater levels of protection against the coronavirus than those who were vaccinated but had no infection. “It makes no difference whether you get infected and then vaccinated, or if you get vaccinated and then a breakthrough infection,” said study senior co-author Fikadu Tafesse, an assistant professor of Molecular Microbiology and Immunology at OHSU. “In either case, you will get a really, really robust immune response – amazingly high.”
Although this study was done before the emergence of the highly transmissible Omicron variant, the researchers expect the hybrid immune responses generated by vaccination combined with Omicron infection to be similar. “The likelihood of getting breakthrough infections is high because there is so much virus around us right now,” said Professor Tafesse. “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.”
According to study senior co-author Bill Messer, another immunologist and expert in Molecular Microbiology at OHSU, each new Omicron breakthrough infection could potentially bring the pandemic closer to the end, and turn into a mostly mild endemic infection instead of a devastating pandemic. “I would expect at this point many vaccinated people are going to wind up with breakthrough infections – and hence a form of hybrid immunity,” he said.
Further research is needed to assess the immune responses following several natural infections with no vaccination. However, the scientists expect that immunity in such cases will be highly variable and that vaccination plus infection remains the best way of gaining super immunity.
The study is published in the journal Science Immunology.