What happens to immunity levels after COVID-19 infection?

Australian scientists have described the evolution of immunity levels up to four months after COVID-19 infection, finding that, although antibody levels drop dramatically in the first to two months, the decrease then decreases substantially.

The results suggest that protective COVID-19 vaccines should generate stronger antibody responses than natural infection.

The research team, including Dr. Jennifer Juno of the University of Melbourne, senior researcher at the Peter Doherty Institute for Infection and Immunity (Doherty Institute), has investigated how the immune system, particularly B and T cells, responds to COVID- Protein 19 peak.

The spike protein allows SARS-CoV-2 to attach and enter cells in humans and is crucial in inducing neutralizing antibodies to protect against reinfection.

B cells are responsible for producing antibodies that recognize SARS-CoV-2, while T cells play an important role in supporting the development of B cell responses.

Dr. Juno said one of his impressive observations was that during the four months that they followed the patients, the number of B cells that recognize the spike protein increased in almost all of them, regardless of the severity of the disease.

“This is interesting because our work and other recent studies suggest that these B cells continue to accumulate and potentially evolve over time. This should be useful for protection in the event of another exposure, in the sense that these ‘memory’ cells should be able to be activated again, “said Dr. Juno.

“Although we still don’t know how many antibodies you really need to be protected, whether through a vaccine or through natural infections, the recent results of phase 3 vaccine tests should allow us to understand how long natural immunity should last.

“In addition, what remains to be understood is whether these changes in B-cell memory can help the immune system recognize and be protected against new variants of SARS-CoV-2 that are emerging today.”

Dr. Juno said that recent data on the main vaccines shows that they are eliciting at least twice the levels of antibodies from the natural infection, which is very encouraging.

Provided by the Doherty Institute for Infection and Immunity