Researchers from the University of Arizona Health Sciences studied the production of antibodies from a sample of nearly 6,000 people and found immunity lasts for at least several months after being infected with SARS-CoV-2, the virus that causes COVID-19.
“We clearly see high-quality antibodies still being produced five to seven months after SARS-CoV-2 infection,” said lead researcher Deepta Bhattacharya, associate professor University of Arizona College of Medicine Tucson’s Department of Immunobiology. “Many concerns have been expressed about immunity against COVID-19 not lasting. We used this study to investigate that question and found immunity is stable for at least five months.”
When a virus first infects cells, the immune system deploys short-lived plasma cells that produce antibodies to immediately fight the virus. Those antibodies appear in blood tests within 14 days of infection. The second stage of the immune response is the creation of long-lived plasma cells, which produce high-quality antibodies that provide lasting immunity.
Researchers tracked antibody levels for more than several months, although they believe immunity lasts much longer.
“This research not only has given us the ability to accurately test for antibodies against COVID-19, but also has armed us with the knowledge that lasting immunity is a reality,” said Dr. Michael Drake, Senior Vice President University of Arizona Health Sciences.
Earlier studies extrapolated antibody production from initial infections and suggested antibody levels drop quickly after infection, providing only short-term immunity. Bhattacharya believes those conclusions focused on short-lived plasma cells and failed to take into account long-lived plasma cells and the high-affinity antibodies they produce.
“The latest time-points we tracked in infected individuals were past seven months, so that is the longest period of time we can confirm immunity lasts,” Bhattacharya said. “That said, we know that people who were infected with the first SARS coronavirus, which is the most similar virus to SARS-CoV-2, are still seeing immunity 17 years after infection. If SARS-CoV-2 is anything like the first one, we expect antibodies to last at least two years, and it would be unlikely for anything much shorter.”
Researchers say they have tested nearly 30,000 people and more antibody tests are still available for anyone in Arizona age 18 and older at multiple locations throughout the state.
Since April, the University of Arizona’s Cole and Jeannie Davis Sports Center has served as a temporary clinic for antibody testing of first responders and health care workers.