How long does coronavirus immunity last? Some studies suggest months

New research is now emerging that suggests a person can have immunity to the new coronavirus as many as eight months after getting infected with the COVID-19 disease.

A study by the La Jolla Institute for Immunology was published online this week, in which the researchers tracked 185 COVID-19 patients, most of whom had recovered from mild disease, and found enough immune cells to protect against infection after six to eight months. The paper is yet to be peer-reviewed.

“Most people have a significant amount of immune memory to this virus for six or more months and for you to have protection from getting a disease again, that has to come from immune memory,” Shane Crotty, a virologist and co-author of the study, told Global News, adding that such an amount is enough to keep people from getting seriously ill for multiple years.

“We don’t know for sure right now which parts of the immune system are the best at stopping this virus, but we’ve got pieces of information that we think are encouraging,” he said on Thursday.

Another paper published in the Immunity medical journal last month found that people with mild cases can produce antibodies that can help fend off the coronavirus for at least five to seven months after infection.

The research, while inconclusive, offers more insight into the virus that has infected more than 56 million people and been connected to at least 1.35 million deaths since it was first reported in China last December.

Other studies have also suggested long-lasting immunity, which experts say is an encouraging sign and bodes well for vaccine development.

“This is important data to take us forward to better understand the long-term response of Sars-Cov-2 or the COVID-19 virus but not definitive at this stage,” Dr. Jim Kellner, a member of Canada’s  COVID-19 Immunity Task Force, told Global News.

According to the World Health Organization (WHO), the majority of people who are infected mount an immune response within a few weeks of infection, but more research is needed on this front.

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“We are still learning about how long the antibodies last,” the WHO told Global News. “So far, we have data that shows that the immune response lasts for several months.”

Anna Banerji, an infectious disease specialist at the University of Toronto, said knowing the time frame for immunity will determine if future vaccines will need to be used more than once or — like the flu shot – once every year.

“There are many different ways that the body responds to a virus — it could be antibodies or other immune cells that respond to an infection. So we don’t know if the immunity to this particular virus will last a lifetime or it will last for a short period of time,” she said.

While developing an immune response means re-infection is less likely, getting COVID-19 again is still possible.

There have already been some cases of the virus mutating and people getting a second infection.

“It probably takes a high level of antibodies to totally prevent infection,” Crotty said.

“Even if you get infected, your immune system may still be able to keep you from getting sick, keep that infection small and keep it asymptomatic, where your immune response may go and kill off all the virus within a few days before you even notice you’ve been infected and so you don’t get sick,” he explained.

— With files from Heather Yourex-West, Global News.

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