How Long Could Covid-19 Immunity Last? It's Not Just About Antibodies

published 26.06.2020 18:00

If people really are experiencing drastic drops in antibody levels a few months post-infection, then using antibody tests as a way to identify people supposedly “safe” from the virus will fall flat on its face.

We have some evidence from studies of other human coronaviruses that antibody levels tend to meaningfully wane after a year or two post-infection, and people can be reinfected around then.

But two to three months later, over 90% of both groups experienced a significant reduction in covid-19 specific IgG antibodies; a majority of both groups also experienced a drop in the antibodies that block the virus from infecting cells, which are called neutralizing antibodies.

A recent study making the rounds everywhere is certainly unnerving: It found that previously infected people can lose almost all of a type of antibody to the coronavirus within three months.

It also further throws into question the notion of using herd immunity—the idea that enough immune people in a population will prevent the virus from spreading to vulnerable segments not yet infected—to get through this pandemic, according to Bruce Walker, an immunologist and director of the Harvard University Center for AIDS Research.