LOS ANGELES, Calif. — As COVID variants like Delta and Omicron have health experts questioning the effectiveness of current coronavirus vaccines, a new study finds a surprising combination that may provide a defense against these mutations. Researchers from UCLA say getting the COVID-19 vaccine and getting sick with earlier strains of COVID combine to produce potent antibodies against newer variants.
For those who have not been infected during the pandemic, study authors say it’s possible that vaccine booster shots could match this antibody response. However, their findings reveal that natural infection and vaccinations team up to provide “maximum protection” against COVID’s variants. The team notes their research started before the emergence of both the Delta and Omicrons strains.
“The main message from our research is that someone who has had COVID and then gets vaccinated develops not only a boost in antibody amount, but also improved antibody quality — enhancing the ability of antibodies to act against variants,” says study senior author Dr. Otto Yang, a professor of medicine at the David Geffen School of Medicine at UCLA, in a university release. “This suggests that having repeated exposures to the spike protein allows the immune system to continue improving the antibodies if someone had COVID then been vaccinated.”
COVID’s spike protein is the portion of the virus which attaches to the surface of human cells. From there, they slice through and hijack the cell’s functions to reproduce more of the virus. In variants (or mutations) of COVID-19, the spike changes shape, making it harder for natural and vaccine antibodies to recognize and stop the virus.
Powerful variant fighters found in the blood
The team compared antibodies in the blood of 15 vaccinated individuals who have never tested positive for COVID-19 with 10 unvaccinated people who contracted COVID-19. Several months later, all 10 unvaccinated patients received the COVID-19 vaccine, with most opting for two doses of either the Pfizer–BioNTech or Moderna two-dose shots.
Study authors examined how these antibody samples responded to encountering a wide variety of spike proteins, featuring common mutations discovered during the pandemic. Results show that mutations in the SARS-CoV-2 virus reduced the potency of antibodies acquired from a previous COVID infection. They also weakened the strength of antibodies coming from coronavirus vaccines in otherwise healthy adults.
However, when a patient had already contracted COVID and then added the antibodies from vaccinations, the combination was able to recognize all of the COVID-19 variants the UCLA team tested. Although booster shots could possibly replicate this effect, Dr. Yang says it’s still unclear if that will hold true.
“Overall, our findings raise the possibility that resistance of SARS-CoV-2 variants to antibodies can be overcome by driving further maturation through continued antigenic exposure by vaccination, even if the vaccine does not deliver variant sequences,” the researchers conclude.
The study is published in the journal mBio.