Scientists have used the renewal theory in probability to limit recall bias in initial case data. The researchers have determined a new estimate for the incubation period of COVID-19. Their mean estimate was 7.76 days, this is longer than the previous estimates of 4 to 5 days.
The estimate involved the largest amount of patient samples to date in such an analysis. The implications of a longer incubation period could help direct safer and more effective quarantine measures. To work effectively, it is imperative that the disease's incubation period be accurately determined, in order to ensure quarantined individuals are separated from the general public for the proper duration.
Previous estimates of 4 to 5 days were based on small samples sizes, limited data, and self-reports that could be biased by the memory of the patient. Jing Qin, and colleagues, developed a low-cost approach to estimate incubation periods and applied it to 1,084 confirmed cases of COVID-19 that had known histories of travel or residency in Wuhan, China. Their approach improves accuracy by relying on a public database of dates of infection, and uses the renewal theory in probability to reduce recall bias.
The team calculated that the median incubation period was 7.75 days, with 10% of patients showing an incubation period of 14.28 days. The authors do highlight a point of caution in that their approach relies on several assumptions and may not apply to later cases where the virus may have mutated.