Tracking Reproductivity of COVID-19 Epidemic in China with Varying Coefficient SIR Model

We propose a varying coefficient Susceptible-Infected-Removal (vSIR) model that allows changing infection and removal rates for the latest corona virus (COVID-19) outbreak in China. The vSIR together with proposed estimation procedures allow one to track reproductivity of COVID-19 through time assess effectiveness control measures implemented since Jan 23 2020 when city Wuhan was lockdown followed by an extremely high level self-isolation population. Our study finds had been significantly slowed down three weeks from January 27th February 17th 96.3% 95.1% reductions effective reproduction numbers R among 30 provinces 15 Hubei cities, respectively. Predictions ending times total infected are made under scenarios rates. paper provides timely associated prediction methods which may be applied other countries track, predict epidemic or infectious diseases