The B cells that create antibodies mature into what are called plasma cells, Bhattacharya said. “Generally, you get a ton of short-lived plasma cells,” he said.
“They make a ton of antibodies.” But these are not antibodies that do much to protect the body from the virus.
“The best cells compete with each other,” he said. “Only those go on to become long-lived cells. Those form later in the response.”
The team has tested close to 30,000 people and has looked at some who have been tested several times.
“I think it’s good news,” Bhattacharya said.
The novel coronavirus has only been around for less than a year, so it will take time to know just how long immunity lasts. “That said, we know that people who were infected with the first SARS coronavirus, which is the most similar virus to SARS-CoV-2, are still seeing immunity 17 years after infection. If SARS-CoV-2 is anything like the first one, we expect antibodies to last at least two years, and it would be unlikely for anything much shorter,” he said.
The severe acute respiratory syndrome virus infected close to 8,000 people and killed about 800 before it was stopped in 2004.
People who were sicker with Covid-19 had a stronger immune response, Bhattacharya said. “The people sampled from the ICU had higher levels of antibodies than people who had milder disease.” He doesn’t yet know what that will mean for long-term immunity.