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People who build up high levels of immune cells from coronaviruses that cause the common cold could have some protection against COVID-19, according to a small study published Monday in Nature Communications.
Previous studies have shown that T cells created from other coronaviruses can recognize SARS-CoV-2, the virus that causes COVID-19. In the new study, researchers at Imperial College London found that the presence of these T cells at the time of COVID-19 exposure could reduce the chance of getting infected.
The findings could provide a blueprint for a second-generation, universal vaccine to prevent infection from COVID-19 variants, including Omicron and ones that crop up later.
“Being exposed to SARS-CoV-2 virus doesn’t always result in infection, and we’ve been keen to understand why,” Rhia Kundu, PhD, the lead study author from Imperial’s National Heart and Lung Institute, said in a statement.
People with higher levels of T cells from the common cold were less likely to become infected with COVID-19, the researchers found.
“While this is an important discovery, it is only one form of protection, and I would stress that no one should rely on this alone,” Kundu said. “Instead, the best way to protect yourself against COVID-19 is to be fully vaccinated, including getting your booster dose.”
For the study, Kundu and colleagues analyzed blood samples from 52 people who lived with someone with confirmed COVID-19 in September 2020. Among the 26 people who didn’t contract COVID-19, there were “significantly higher levels” of pre-existing T cells from common cold coronaviruses, as compared with the 26 people who did become infected.
The T cells researched in the study are considered “cross-reactive” and can recognize the proteins of SARS-CoV-2. They offer protection by targeting proteins inside the SARS-CoV-2 virus, rather than the spike proteins on the surface that allow the virus to invade cells.
The current COVID-19 vaccines target the spike proteins, which are more likely to mutate than internal proteins, the researchers wrote. The Omicron variant, for instance, has numerous mutations on spike proteins that may allow it to evade vaccines.
The data suggests that the next step of COVID-19 vaccine development could focus on internal proteins, the researchers said, which could provide lasting protection because T cell responses persist longer than antibody responses that fade within a few months of vaccination.
“New vaccines that include these conserved, internal proteins would therefore induce broadly protective T cell responses that should protect against current and future SARS-CoV-2 variants,” Ajit Lalvani, MD, the senior study author and director of Imperial’s Respiratory Infections Health Protection Research Unit, said in the statement.
But more research is needed, the authors said, noting that the study had a small sample size and lacked ethnic diversity, which puts limits on the research.
Nature Communications: “Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts.”
Imperial College London: “T cells from common colds cross-protect against infections with SARS-CoV-2.”
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