Protective immunity against COVID-19 could last 8 months or more

Editor's Note

This study led by researchers from the Center for Infectious Disease and Vaccine Research, La Jolla Institute for Immunology, La Jolla, California, finds that response to COVID-19 by the immune system can last for at least 8 months after the onset of symptoms.

The researchers measured antibodies, memory B cells, helper T cells, and killer T cells in blood samples from 188 COVID-19 patients.

The researchers found that:

• COVID-19-virus-specific antibodies persist in the bloodstream months after infection, and memory B cells are at the ready to reactivate and produce more antibodies to fight reinfection if a person encounters COVID-19 again.
• COVID-19 spike protein-specific memory B cells increased in the blood 6 months after infection.
• COVID-19 survivors had an army of T cells ready to fight reinfection—helper T cells lingered, ready to trigger an immune response if they saw COVID-19 again,  and killer T cells remained, ready to destroy infected cells and halt a reinfection.

These findings imply that there is a good chance people will have protective immunity for at least 8 months and probably well beyond, the researchers say. It is also possible that immune memory will be similarly long lasting following vaccination.

The researchers are continuing to analyze blood samples from these 188 patients and hope to track their responses 12 to 18 months after their onset of symptoms. They also plan to evaluate the immune response following vaccination.