Effective containment explains sub-exponential growth in confirmed cases of recent COVID-19 outbreak in Mainland China

Benjamin F Maier; Dirk Brockmann

is the (which was not peer-reviewed) The copyright holder for this preprint . https://doi.org/10.1101/2020.02.18.20024414 doi: medRxiv preprint All fits were performed with fixed values of R 0,free = 6.2 and T I = 8d. Note that the effective, observed basic reproduction number R 0,eff has lower values and varies for each of the affected provinces as discussed in Sec. IV and shown in Tab. I. A: In Hubei, the model captures both, the initial rise of confirmed cases as well as the subsequent algebraic growth. The confirmed cases are predicted to saturate at C = 51, 000. The model also predicts the time-course of the number of unidentified infectious individuals I(t) which peaks on Feb. 7th and declines exponentially afterwards. While the order of I(t) is associated with rather large fluctuations depending on the fitting procedure, the predicted peak time is robust, consistently around Feb. 7th. B: Model prediction for case numbers aggregated over all affected provinces other than Hubei. The case numbers' algebraic growth is well reflected and predicted to saturate at C = 12, 600. In contrast to Hubei, the fraction of unidentified infecteds peaks around Feb. 1st, approximately a week earlier. The insets in A and B depict both data and fits on a log-log scale. C: Fits for confirmed cases as a function of time for the remaining 8 most affected provinces in China. All curves are well captured by the model fits that predict similar values for the peak time of unidentified infecteds. the transmission process in the same way and (ii) case counting is decoupled from the quarantine process (see App. C). We find that these model variants describe the real case count data reasonably well for the majority of provinces, further evidence of the importance of containment policies that target the susceptible population. In App. B we present further analytical evidence for this conclusion.