Quantifying bias of COVID-19 prevalence and severity estimates in Wuhan, China that depend on reported cases in international travelers

Abstract

Risk of COVID-19 infection in Wuhan has been estimated using imported case counts of international travelers, often under the assumption that all cases in travelers are ascertained. Recent work indicates variation among countries in detection capacity for imported cases. Singapore has historically had very strong epidemiological surveillance and contact-tracing capacity and has shown in the COVID-19 epidemic evidence of a high sensitivity of case detection. We therefore used a Bayesian modeling approach to estimate the relative imported case detection capacity for other countries compared to that of Singapore.We estimate that the global ability to detect imported cases is 38% (95% HPDI 22% -64%) of Singapore's capacity. Equivalently, an estimate of 2.8 (95% HPDI 1.5 -4.4) times the current number of imported cases, could have been detected, if all countries had had the same detection capacity as Singapore. Using the second component of the Global Health Security index to stratify likely case-detection capacities, we found that the ability to detect imported cases relative to Singapore among high surveillance locations is 40% (95% HPDI 22% -67%), among intermediate surveillance locations it is 37% (95% HPDI 18% -68%), and among low surveillance locations it is 11% (95% HPDI 0% -42%). Using a simple mathematical model, we further find that treating all travelers as if they were residents (rather than accounting for the brief stay of some of these travelers in Wuhan) can modestly contribute to underestimation of prevalence as well. We conclude that estimates of case counts in Wuhan based on assumptions of perfect detection in travelers . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. : medRxiv preprintterm can be well approximated as We plot this approximation of V given doubling times . V ≈ 1 − e −(r+γ)d aligned with 4 , a range of durations of detectable infection and a range of lengths of stay 2 ( Figure 2 ). Results:We estimate that the global ability to detect imported cases is 38% (95% HPDI 22% -64%) of Singapore's capacity. Equivalently, an estimate of 2.8 (95% HPDI 1.5 -4.4) times the current number of imported cases, could have been detected, if all countries had had the same detection capacity as Singapore, which leads to 1.8 (95% CI 0.5 -3.4) undetected cases per detected case. The ability to detect imported cases among high surveillance countries is 40% (95% HPDI 22% -67%), among intermediate surveillance countries it is 37% (95% HPDI 18% -68%), and among low surveillance countries it is 11% (95% HPDI 0% -42%). : medRxiv preprint 7In this paper, we have aimed to test two assumptions underlying the estimation of incidence at the epicentre of the SARS-Cov2 outbreak. The first of these is that the capacity for detection of international imported cases is 100% sensitive and specific across locations. While we know of no reason to doubt specificity of detection, we tested the assumption of perfec...

Evolving Epidemiology and Impact of Non-pharmaceutical Interventions on the Outbreak of Coronavirus Disease 2019 in Wuhan, China

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