In a new study, researchers found that people who have been infected with the COVID-19 virus have immune memory to protect against reinfection for at least eight months.
The research is the strongest evidence for the likelihood that vaccines against the virus, SARS-CoV-2, will work for long periods.
The research was conducted by a team from Monash University and elsewhere.
Previously, many studies have shown that the first wave of antibodies to coronavirus wane after the first few months, raising concerns that people may lose immunity quickly.
In the study, the team found the discovery that specific cells within the immune system called memory B cells, “remembers” infection by the virus, and if challenged again, through re-exposure to the virus, triggers a protective immune response through rapid production of protective antibodies.
The researchers recruited a cohort of 25 COVID-19 patients and took 36 blood samples from them from Day 4 post-infection to Day 242 post-infection.
As with other studies — looking only at the antibody response — the researchers found that antibodies against the virus started to drop off after 20 days post-infection.
However — importantly — all patients continued to have memory B cells that recognized one of two components of the SARS-CoV-2 virus, the spike and nucleocapsid proteins.
These virus-specific memory B cells were stably present as far as eight months after infection.
According to the team, the results give hope to the efficacy of any vaccine against the virus and also explains why there have been so few examples of genuine reinfection across the millions of those who have tested positive for the virus globally.
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.
One author of the study is Associate Professor Menno van Zelm.
The study is published in Science Immunology.
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