Covid-19 antibodies may give us partial immunity to SARS and MERS

Antibodies from people who have had covid-19 or been vaccinated against it may give them partial protection against most other pathogens in the coronavirus family.

As a result of the virus behind the covid-19 pandemic, and related vaccination campaigns, many people may have some immunity to other coronaviruses, including two that could cause dangerous outbreaks in the future.

Someone being vaccinated against covid-19 in Los Angeles, California, in April 2021
Mario Tama/Getty Images

This includes the virus behind SARS, which started spreading in China in 2002 and killed around 1 in 10 of those infected before it was stopped by infection control measures, as well as the deadlier virus behind MERS, which kills 1 in 3 infected people. Small outbreaks of MERS still occur when the virus crosses to people from camels.

“We were hoping that there would be [some antibody binding] but I wasn’t expecting to see so much,” says Florian Krammer at the Icahn School of Medicine at Mount Sinai, New York. “I’m happy to see it.”

In the study, Krammer and his colleagues took blood samples from 85 people in the US who had either received two or three doses of one of the mRNA-based vaccines against covid-19, had been infected with the virus SARS-CoV-2, which can cause covid-19, or both. They compared these with 15 blood samples taken from people in the two years before the pandemic reached the US.

The blood was tested for antibodies against 21 different coronaviruses, including three variants of SARS-CoV-2, the virus behind SARS, the one behind MERS and four that cause common cold-like symptoms.

The pre-pandemic blood samples generally had no antibodies that could bind to the coronaviruses tested, although some could bind to two cold-causing coronaviruses called OC43 and HKU1, as well as a virus that affects cows, which is thought to share a common ancestor with OC43.

The samples taken during the pandemic, however, had antibodies that bound to most of the 21 viruses to some degree. This suggests a level of immunity that, while it probably wouldn’t prevent infection, would protect against severe illness and death, says Krammer. People may also have some protection against coronaviruses from T-cells, the other main arm of their immune system, he says.

Being infected with a cold-causing coronavirus is thought to bring about immunity only to that specific virus, so it is unclear exactly why infection with SARS-CoV-2 and covid-19 vaccines generated such broad immunity, says Krammer. “I think the pandemic changed a lot,” he says. “A lot of us have circulating antibodies that cross-react and a lot of us have immune memory that can cross-react.”

Compared with other coronaviruses, the one behind covid-19 is “quite different”, says Paul Klenerman at the University of Oxford. The broader immunity from SARS-CoV-2 could be because many people had a more severe infection with it than with a typical cold-causing coronavirus, he says.

The findings don’t mean that health authorities can stop making preparations for the next dangerous pandemic, such as one caused by a relation of the viruses behind SARS or MERS, because a new coronavirus could still cause many deaths, says Krammer. A pandemic could also be triggered by a completely different virus, such as bird flu.

Nevertheless, the work might help in developing vaccines that give strong protection against the whole coronavirus family, he says.


MedRxivDOI: 10.1101/2023.08.01.23293522

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