Recent preliminary research might offer some comfort to the many vaccinated Americans who came across Omicron this past winter. A pair of studies suggest that vaccinated people who caught the variant went on to develop a strong and diverse immune response to the SARS-CoV-2 coronavirus in general — more so than people who were vaccinated and boosted or people who were only infected with Omicron. The findings could also indicate that an updated booster, perhaps specific to Omicron, will be more effective at ensuring longer-term immunity moving forward.
The results come from two preprint papers released on the website bioRxiv in April and May: one from University of Washington researchers and the other from researchers at BioNTech, the company that, along with Moderna, developed the FDA-approved Spikevax COVID-19 vaccine.
The studies collected blood samples from various groups of patients and looked for biomarkers of immunity to the coronavirus, namely virus-specific antibodies and immune cells. These groups included people with an Omicron infection who had previously gotten two or three vaccine doses; vaccinated/boosted people who had caught the original virus or the Delta variant; vaccinated/boosted people who hadn’t caught any infection; and unvaccinated people who had freshly caught Omicron.
Overall, it was the vaccinated people with Omicron who appeared to have the most robust antibodies — not just to Omicron, but to the original SARS and SARS-CoV-2 virus and variants like Delta. The same pattern was seen with these individuals’ memory B-cells, the cells responsible for producing new antibodies in response to a familiar germ. However, unvaccinated people who were only infected with Omicron did not develop the same type of broad immune response.
The Washington study also found neutralising antibodies in the noses of these Omicron-infected and vaccinated people, which could provide a hardier defence against future infections. And they identified an antibody that seemed to be especially potent against various strains of the virus — one that might warrant further study as a potential treatment that can be reproduced in the lab.
The findings of both papers have yet to go through formal peer review, so they should be viewed with added caution. But they do line up with past research suggesting that people with hybrid immunity to the coronavirus — the result of being vaccinated and infected, in either order — can promote a broader immune response, particularly when people are infected by different variants. In contrast, other research has found that unvaccinated people infected with Omicron do not seem to develop durable protection against other variants of the virus.
At the very least, the new findings suggest that vaccinated people who caught Omicron should be well-protected, for the time being at least. In the U.S., that’s a large sample size, with one study estimating that as many as three-fourths of Americans may have caught it this winter. And because Omicron is so evolutionarily distinct from other lineages of the virus, it’s also possible that an updated booster specific to it could provide a more diverse immune response than the booster available now, which is still tailored to the original strain of the virus.
“That indicates that we are at the point where we may want to consider having a different vaccine to boost people,” David Veesler, an assistant professor at the University of Washington and lead researcher of the Washington study, told Bloomberg News.
Of course, the virus isn’t standing still. There are already other Omicron-related lineages out there, some of which may be capable of evading immunity even in people who have been vaccinated and infected with Omicron. And the continued evolution of the virus may very well require regular boosters or different vaccine strategies, such as nasal sprays, to effectively prevent large waves of illness in the future.
But even if we can develop these updated vaccines effectively enough, there are still more challenges ahead. Booster vaccination rates in the U.S. are far below the rates seen in similar countries, and funding shortages may mean that any available shots this year may have to be rationed to the most high-risk Americans.