How would changes in case definitions affect inferences on the transmission dynamics of COVID-19 in China?
HKU SPH researchers recently published a paper on Lancet Public Health about the effect of changing case definitions of COVID-19 on the epidemic curve and transmission parameters in mainland China during the first epidemic wave. They summarized seven versions of case definitions issued in China, which were initially narrow and were gradually broadened as knowledge increased. They estimated that when the case definitions were changed, the proportion of infections being detected as cases increased. They also estimated that if the fifth version has been applied throughout the outbreak with sufficient testing capacity, there would have been more than 230,000 confirmed cases by Feb 20, 2020, compared with the 55,508 confirmed cases reported on that date.
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