[Epidemic characteristics and trend analysis of the COVID-19 in Hubei province]

Objective: By describing and analyzing the epidemic characteristics and trends of the attack rate, the crude mortality and relevant indexes in Hubei province during the pandemic of COVID-19 to provide comprehensive evaluations of the epidemic trends and the effects of intervention measures. Methods: Based on the case data reported in Hubei province during the COVID-19 epidemic, combined with the important time of major interventions and event, the cumulative attack rate, the sequential increase rate of new cases, baseline increase rate of new cases, the observation- confirmed case conversion rate, the cumulative crude mortality, the daily severe case rate, and the ratio of death to severe were used to describe and analyze the epidemic characteristics in different phases of the COVID-19 epidemic. Results: The epidemic experienced an outbreak phase from January 10 to February 3 with large amount of case reported, a peak phase from February 4 to February 19 with continuous increasing number of new cases and deaths, a platform phase from February 20 to March 3 with balanced diagnosis and treatment number, and a descending phase from March 4 to March 18 with decreased diagnosis and increased treatment number. Up to March 18, the cumulative attack rate of the COVID-19 epidemic in Hubei province increased from 0.03/10 000 on January 19 to 11.46/10 000, from 0.04/10 000 on January 10 to 45.13/10 000 in Wuhan city, and from 0.002/ 10 000 on January 20 to 3.70/ 10 000 in other areas of Hubei province other than Wuhan city. The increase rate of new cases fluctuated during the epidemic period and reached the highest at February 12 in Hubei province. The cumulative crude mortality in Hubei Province increased rapidly from 1.01% on January 19 to 5.13% on January 26, then decreased to 2.54% on February 13, and then slowly increased to 4.62% on March 18, and similar trend was also observed in Wuhan city. The daily severe rate in Hubei Province increased from 26.88% on January 27 to 34.27% on March 18. The ratio of death to severe decreased from 7.37% on January 23 to 0.35% on March 18. Conclusions: The epidemic cycle of COVID-19 in Hubei province proposed to be 60 days, which was about 1.76 times of the combination of the longest incubation period or isolation period (14 d) and the average hospitalization time of confirmed patients in Hubei province (20 d). It suggested that the major anti-epidemic decisions made in China were effective.