A new study carried out by researchers, including from Monash University in Australia, found that Covid-19 survivors have an immune memory that can last for at least eight months, protecting them against re-infection.
The study, published in the journal Science Immunology, found that certain cells in the immune system called memory B cells “remember” the infection from the virus. When a person is exposed to the virus again, the B cells trigger a protective immune response by rapidly producing protective antibodies.
This also provided strong evidence of the likelihood that Covid-19 vaccines would work over long periods of time.
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For the study, the researchers recruited a cohort of 25 Covid-19 patients and took 36 blood samples from them from day 4 after infection to day 24 after infection.
The scientists found that antibodies to the virus fell off 20 days after infection.
However, they said that all of the patients continued to have memory B cells that recognized one of two components of the virus – the spike protein, which helps the virus enter host cells, and the nucleocapsid proteins.
Based on their analysis, the researchers said these virus-specific storage B cells were stably present for up to eight months after infection.
The scientists speculated that their study gives hope for the effectiveness of a vaccine against the virus. It also explains why there have been very few cases of reinfection in the millions of people who tested positive for the virus worldwide.
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The co-author of the study, Menno van Zelm of the Institute of Immunology and Pathology at Monash University, said in a statement: “These results are important as they definitely show that patients infected with the Covid-19 virus actually retain their immunity to the virus and the disease. ”
“This was a black cloud hanging over the potential protection any Covid-19 vaccine could offer and gives real hope that once a vaccine or vaccines are developed, they will provide long-term protection,” said van Zelm.