Immunity to COVID-19 lasts up to 8 months after infection, study reveals

MELBOURNE, Australia — As coronavirus vaccines finally get distributed across the world, the next question is how long will they last. A new study is giving health officials hope that treatments will have a long lifespan after discovering that the human body is already resilient to reinfection. Researchers from Monash University in Australia say people who have contracted COVID-19 have an immune memory that lasts at least eight months.

While previous studies show that patients likely only carry antibodies to coronavirus for a few months, the Australian team says their findings are the strongest evidence that vaccines will provide long-lasting protection. The new report finds specific cells in the immune system, memory B cells, actually “remember” the infection caused by COVID-19. If challenged again by the virus, memory B cells trigger an immune response which rapidly produces new antibodies.

The study examined 36 blood samples from 25 COVID patients. Researchers looked at the immune reactions starting on Day 4 post-infection through Day 242 post-infection.

Although the results show the number of antibodies against coronavirus begin to decrease after 20 days post-infection, patients continue to possess memory B cells that recognize one of two key components of the SARS-CoV-2 virus. These are the spike and nucleocapsid proteins. Researchers say memory B cells retain their COVID memory even eight months after the first infection.

‘Results show definitively that patients infected with COVID-19 virus retain immunity’

Monash Associate Professor Menno van Zelm says the results also explain why there have been so few incidents of COVID reinfection among the millions of people testing positive during the pandemic.

“These results are important because they show, definitively, that patients infected with the COVID-19 virus do in fact retain immunity against the virus and the disease,” van Zelm says in a media release.

“This has been a black cloud hanging over the potential protection that could be provided by any COVID-19 vaccine and gives real hope that, once a vaccine or vaccines are developed, they will provide long-term protection.”

The study appears in the journal Science Immunology.