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People who have been infected with the COVID-19 virus have sustained protection against reinfection for at least eight months, according to Australian researchers.

The findings suggest that vaccines against the virus will work for long periods, debunking many previous studies which showed that the first wave of antibodies to coronavirus wane after the first few months and raised concerns that people lose immunity quickly.

A collaboration between Monash University, the Alfred Hospital and the Burnet Institute, the study found a specific cell within the immune system called the memory B cell, which remembers infection by the virus, and if challenged again through re-exposure to the virus, triggers a protective immune response through rapid production of antibodies.

Researchers recruited 25 COVID-19 patients and took 36 blood samples from them from Day four post infection to Day 242 post infection.

As with other studies – looking only at antibody response – researchers found that antibodies against the virus began to drop off after 20 days post infection.

Importantly though, all patients continued to have memory B cells that recognised one of two components of COVID-19, the spike and nucleocapsid proteins. These virus-specific memory B cells were present up to eight months after infection.

According to lead researcher, Associate Professor Menno van Zelm, from Monash University’s Department of Immunology and Pathology, the results give hope to the efficacy of any vaccine against the virus and explain why there have been so few examples of reinfection across the millions of people who have contracted 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,” he said.

“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.”