Research suggests COVID-19 immunity could last for months or longer

If someone has tested positive for COVID-19, how long can immunity last?

Researchers say they now have the answers thanks to blood tests. The findings, based on analyses of blood samples from 188 COVID-19 patients, suggests immunity can last for at least eight months after the onset of symptoms from the initial infection, according to research published in SCIENCE this week.

Dr. Alessandro Sette, with The La Jolla Institute for Immunology, said immunity could last eight months or possibly longer.

Survivors of SARS from 2003 still have immune memory cells in their blood. Those cells are key to surviving a future infection.

“The virus arrives and the cells that are born literally to recognize that thing – they go crazy … So they start to multiply,” Sette said. “Now you have a thousand cells. So what happens is, if a virus comes back – the race between your immune system and the virus starts again. But the immune system starts from 1,000-fold more cells. And so it wins.

This doesn’t mean someone who has survived COVID-19 can stop taking precautions, Sette said.

There is a range in natural immune responses, he said. Some can be on the low end. Additionally, someone could become reinfected and be asymptomatic and pass on the infection, he said.