Scientists studying the coronavirus are hopeful after multiple studies have found that people who have even a mild case of COVID-19 are showing signs of lasting immunity. While the antibodies that fight off the infection disappear after a few weeks, researchers are finding that low levels of the antibodies remain in a person's system, which would allow them to fight off a new infection.
"The antibodies decline, but they settle in what looks like a stable nadir," Dr. Deepta Bhattacharya told the New York Times. "The response looks perfectly durable."
The studies have not been peer-reviewed yet, but researchers believe the data shows that even mild cases of COVID-19 are capable of providing lasting immunity from a second infection.
"This is exactly what you would hope for," Marion Pepper, an immunologist at the University of Washington who authored one of the new studies, said. "All the pieces are there to have a totally protective immune response."
One study found that T cells, which fight off a virus when it enters your body, persist in a person's blood for months after they have recovered. When the T cells were exposed to the coronavirus in a lab, they cloned themselves and began aggressively fighting off the infection.
Scientists do not know how long the immunity will last and will need to conduct more studies to definitively determine if the remaining antibodies are capable of preventing a second infection from taking hold.
"This is very promising," said Smita Iyer, an immunologist at the University of California, Davis, who is studying immune responses to the coronavirus in rhesus macaques but was not involved in the new studies. "This calls for some optimism about herd immunity, and potentially a vaccine."
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