Once the coronavirus enters the body, the immune system springs into action, producing antibodies that bind to and neutralize the virus. This immune protection has “memory” so the next time the body encounters the same pathogen, it can identify it quickly and shield against reinfection.
Previous studies had sparked a debate about just how long this sustained immune protection against SARS-CoV-2 lasts because patients’ antibody levels were found to take a dive in the first few months following recovery.
Australian researchers have now, for the first time, demonstrated that COVID-19 survivors could, in fact, rely on their immune defenses to thwart reinfection for at least 8 months. This new data also helps ease other concerns that newly-developed COVID vaccines will not be able to confer protection over long periods.
Menno van Zelm from Monash University, together with a team of collaborators, published their findings in the high-ranking journal, Science Immunology. As part of the study, the team followed a cohort of 25 COVID-19 patients, taking blood samples from early during infection up to 242 days since their diagnoses.
The team did note the characteristic “drop off” of antibody levels at around two weeks after infection. Critically, however, using flow cytometry they also showed that the patients had antibody-producing memory B cells in their blood. These cells specifically targeted the spike and nucleocapsid proteins of SARS-CoV-2. These B cells lingered for at least eight months, indicating that the patients would be safeguarded against reinfection during this period and possibly beyond.
"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," said van Zelm.
"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."