CORONAVIRUS | Levels of an antibody found in recovered Covid-19 patients fell sharply in two to three months after infection for both symptomatic and asymptomatic patients, according to a Chinese study, raising questions about the length of any immunity against the novel coronavirus.

The research, published in Nature Medicine on June 18, highlights the risks of using Covid-19 'immunity passports' and supports the prolonged use of public health interventions such as social distancing and isolating high-risk groups, researchers said...