Natural immunity to Covid-19 may be long-lasting: Study

A recent study has revealed that immunity triggered by SARS-CoV-2 infection could last longer than previously thought. The long-lasting antibody levels and immune memory cells could potentially lessen the severity of a re-infection.

The Vaccine Alliance, Gavi, disclosed the research findings on its website recently.

The researchers have found that people with COVID-19 seemed to have fairly robust and long-lasting immune responses. The antibodies lasted well, with a small drop in levels at 6-8 months after infection.

They also found that T cells levels reduced slightly, and B cells increased – a finding they can't explain.

In this pre-print, scientists looked at immunity to SARS-CoV-2 in 185 people with Covid-19, 41 of whom were more than six months past the initial infection. Most of the people studied had mild symptoms and had not required hospitalisation.

The researchers looked at four elements of the immune response – antibody levels, memory B cells (that remember the pathogen and when exposed to it again, trigger a rapid antibody response) and T cells (CD4 and CD8, that can help B cells or kill infected cells, respectively).

However, the scientists emphasise that these findings are not conclusive evidence of long-lasting protective immunity after SARS-CoV-2 infection because the mechanisms of immunity after COVID-19 have not been explicitly described.