Asymptomatic infection may lead to greater immunity

Monica Gandhi, professor of medicine and infectious diseases specialist, University of California San Francisco

- POOJA BIRAIA JAISWAL

IN THE JOURNAL of General Internal Medicine, Monica Gandhi writes about the hypothesis that universal masking reduces the “inoculum” or dose of the virus inhaled, leading to milder, asymptomatic infections. She tells THE WEEK how asymptomatic Covid-19 infections could be helpful and about other findings in her research. Edited excerpts:

Q/ You say that a high rate of asymptomatic infection is good.

A/ Yes, a high rate of asymptomatic infection in Covid-19 can be a good thing. This virus has protean manifestations, ranging from no symptoms to severe disease and death. In mid-July, the Center for Disease Control and Prevention in the US estimated the rate of asymptomatic infection with Covid-19 to be 40 per cent. Asymptomatic infection can be a problem (in terms of spread), but getting infected and not being sick is a good outcome for a patient.

Moreover, if individuals develop immunity to Covid-19 after asymptomatic infection, that is helpful in slowing down the spread of the disease. There is accumulating evidence that cell-mediated immunity develops after asymptomatic infection. There are two arms to the immune response—antibodies and cell-mediated immunity. Cell-mediated immunity provides longer term protection and, if this develops to asymptomatic infection, it is a very good outcome.