Protection against COVID-19 reinfection may last only for months

Study finds that 20-30% of those who had COVID-19 had poor neutralising activity against the virus after six months

A longitudinal cohort study in India has found that some people who had COVID-19 lacked meaningful immunity against the novel coronavirus to prevent reinfection months later. The study found that 20-30% of infected people had declining virus neutralising activity despite having stable seropositivity six months later. The declining neutralising activity seen in 20-30% of infected people would mean that they might be vulnerable to reinfection. Studies are now under way to understand the presence and activity of memory T cells which can prevent the infection from progressing to severe disease. The first serosurvey was carried out in August-September 2020 and the six-month follow-up was carried out from the end of January to February 2021.