Since the novel coronavirus-infected pneumonia (NCIP) was firstly discovered in Wuhan, and it’s the worst affected area, so we select the data of Wuhan to make the analysis. We got the NCIP data from National Health Commission of the People’s Republic of China, Health Commission of Hubei Province and Wuhan Municipal Health Commission(the data is publicly available). At the same time, the data on temperature, air pressure, relative humidity, and wind speed were obtained from the National Meteorological Center of CMA(http://data.cma.cn/)..
The daily new confirmed cases in Wuhan from 26 December 2019 to 16 March 2020 are presented in Figure 1. We found that the new confirmed cases on February 12 had a sudden sharp increase, that’s because it contains 12364 cases clinical diagnosis(with the deepening of the understanding of COVID–19, and according to the characteristics of the outbreak, the national health committee general office and the office of the state administration of traditional Chinese medicine issued "Novel coronavirus infection pneumonia diagnosis and treatment scheme (trial fifth edition) ",, which added “clinical diagnosis” in the case diagnosis category. In this way, patients can receive standard treatment as the confirmed cases as early as possible, and improve the treatment success rate. The number of clinically diagnosed cases have been included in the number of confirmed cases in Hubei province from February 12).
We also noticed that between 17 January and 26 January 2020, the average daily new cases are 65, but then there were 892 new clinically diagnosed cases on 27 January 2020, and after that day, the daily new cases became much high. Actually before 10 January 2020 the cases were identified as the “pneumonia of unknown etiology”, and when its pathogen preliminary was identified as a novel coronavirus, the national, provincial and municipal expert group immediately revised and improved the treatment of viral pneumonia. By 24:00 on January 10, 2020, 41 cases of the novel coronavirus pneumonia were diagnosed. During the 23 days from 26 December 2019 to 17 January 2020, the number of confirmed NCIP cases in the official data rose from 4 to 59, and then fell to 41, with no new cases for 12 days.
We have investigated the association between the spread of NCIP and 9 weather parameters: mean temperature, maximum temperature, minimum temperature, mean relative humidity, mean air pressure, maximum air pressure, mean wind velocity, maximum wind velocity, precipitation.
We calculated the correlation between the daily new cases of NCIP and each meteorological factor. Considering the mean incubation period of 5.2 days, and the meantime of 0 to 3 days from the onset of clinical symptoms of NCIP to hospital admission[1], we investigated for up to 11 days before the date of onset.
The date was further investigated to determine the effect of weather conditions in the 11 days before clinical diagnosis. Parameters producing significant correlations(P < 0.5) were then used in multiple stepwise linear regression modeling to identify the meteorological factors most strongly correlated with the spread of NCIP.