Combination of Natural Infection and Vaccination Provides Maximum Protection Against COVID Variants

A combination of vaccination and naturally acquired infection appears to boost production of maximally potent antibodies against the COVID-19 virus, new UCLA study finds.

The findings, published Dec. 7, 20221, in the peer-reviewed journal mBio, raise the possibility that vaccine boosters may be equally effective at improving the ability of antibodies to target multiple variants of the virus, including the delta variant. , which is now the predominant strain, and the recently discovered omicron variant. (The study was conducted before the emergence of delta and omicron, but Dr. Otto Yang, the study’s senior author, said the results could potentially apply to those and other new variants.)

“The main message from our research is that someone who has had COVID and is subsequently vaccinated develops not only an increase in the amount of antibody, but also an improved quality of the antibodies – improving the ability of antibodies to act against variants. said Yang, a professor of medicine in the division of infectious diseases and microbiology, immunology and molecular genetics at the David Geffen School of Medicine at UCLA. “This suggests that repeated exposure to the spike protein allows the immune system to continue to improve the antibodies if someone had COVID and was subsequently vaccinated.”

(The spike protein is the part of the virus that binds to cells, resulting in infection.)

Yang said it is not yet known whether the same benefits will be realized for people who have repeated vaccinations but have not contracted COVID-19.

The researchers compared blood antibodies in 15 vaccinated people who had not previously been infected with SARS-CoV-2, the virus that causes COVID-19, to infection-induced antibodies in 10 people who were recently infected with SARS-CoV-2 but had not yet been vaccinated. Several months later, the 10 participants in the last group were vaccinated, after which the researchers reanalyzed their antibodies. Most people in both groups had received the two-dose Pfizer-BioNTech or Moderna vaccines.

The scientists evaluated how antibodies worked against a panel of spike proteins with several common mutations in the receptor binding domain, which is the target of antibodies that help neutralize the virus by preventing it from binding to cells.

They found that the mutations in the receptor binding domain reduced the potency of antibodies obtained by both natural infection and vaccination alone to about the same extent in both groups of people. However, when previously infected people were vaccinated about a year after natural infection, the potency of their antibodies was maximized to a point where they recognized all the COVID-19 variants the scientists tested.

“Overall, our findings raise the possibility that resistance of SARS-CoV-2 variants to antibodies can be overcome by stimulating further maturation through continued exposure to antigens through vaccination, even if the vaccine does not deliver variant sequences,” the researchers write. They suggest that repeated vaccinations could accomplish the same thing as getting vaccinated after having COVID-19, although further research will be needed to address that possibility.

For more information about this study, see Infection Plus Vaccination Provides Better Protection Against COVID-19 Variants.

Reference: “Infection plus vaccination yields better antibodies against COVID-19 variants” by F. Javier Ibarrondo, Christian Hofmann, Ayub Ali, Paul Ayoub, Donald B. Kohn, and Otto O. Yang, December 7, 2021, mBio.
DOI: 10.1128/mBio.02656-21

The other authors of the study are F. Javier Ibarrondo, Christian Hofmann, Ayub Ali, Paul Ayoub and Dr. Donald Kohn, all from UCLA.

The research was funded by the AIDS Healthcare Foundation and several private donors.