4. Observational study: prospective longitudinal cohort
In this paper just published in the New England Journal of Medicine, the authors report the natural history of asymptomatic SARS-CoV-2 infection from part of the cohort of the 410 infected people on the cruise ship, Diamond Princess, who were asymptomatic at the time of testing. Ninety-six people infected with SARS-CoV-2 who were asymptomatic at the time of testing, and 32 cabinmates who tested negative on the ship, were transferred from the Diamond Princess to a hospital in central Japan between February 19 and February 26 for continued observation. Clinical signs and symptoms of Covid-19 subsequently developed in 11 of these 96 people, a median of 4 days after the first PCR test, which meant that they had been presymptomatic rather than asymptomatic. The risk of being presymptomatic increased with age. Eight of 32 cabinmates with a negative PCR test on the ship had a positive PCR test within 72 hours after arrival in the hospital but remained asymptomatic. In total, data on 90 people with asymptomatic SARS-CoV-2 infection, defined as persons who were asymptomatic at the time of the positive PCR test and remained so until the resolution of infection (as determined by two consecutive negative PCR tests), were reported. The authors concluded that, in this cohort, the majority of asymptomatically infected people remained asymptomatic throughout the course of the infection. The time to the resolution of infection increased with age.
View Article: https://www.nejm.org/doi/full/10.1056/NEJMc2013020