Estimating the Asymptomatic Proportion of 2019 Novel Coronavirus onboard the Princess Cruises Ship, 2020

Kenji Mizumoto; Katsushi Kagaya; Alexander Zarebski; Gerardo Chowell

If asymptomatic cases where missed as a result of this, it would mean we have underestimated the asymptomatic proportion. Second, it is worth noting that the data of passengers and crews employed in our analysis is not a random sample from the general population. Considering that most of the passengers are 60 years and older, the nature of this age distribution may lead to underestimation if older individuals tend to experience more symptoms. An age standardized asymptomatic proportion would be more appropriate in that case. Third, the presence of symptoms in cases with COVID-19 may correlate with other factors unrelated to age including prior health conditions such as cardiovascular disease, diabetes, immunosuppression. Therefore, more detailed data documenting the baseline health of the individuals including the presence of underlying diseases or comorbidities would be useful to remove the bias in estimates of the asymptomatic proportion.