As of January 29, 2020, the research team has extracted 1099 laboratory confirmed patients with new coronavirus infection (covid-19) caused by sars-cov-2 from 552 hospitals in 31 provinces, autonomous regions and municipalities directly under the central government. This study analyzed the distribution characteristics of patients in different age groups, the symptoms of infected persons, contact history, imaging manifestations, treatment methods, clinical outcomes (including mortality), etc. The study points out that strict and timely epidemiological measures are essential to curb the rapid spread of the epidemic, and the effective treatment of the disease still needs continuous efforts.
Only 1.9% of patients have direct contact with wild animals
It is worth noting that nearly half of the new crown patients may not have fever when they are admitted to the hospital, but with the progress of the disease, nearly 90% of the patients have fever; it is clear that the symptoms of the digestive tract are relatively rare, but it is also pointed out that the evidence of the transmission of the new crown virus through the digestive tract (the virus is isolated in the feces, gastrointestinal damaged mucosa, bleeding place), suggesting that all sectors of society need to We should pay attention to the prevention of fecal oral transmission.
Novel coronavirus pneumonia patients with novel coronavirus pneumonia and clinical symptoms but no imaging abnormalities were admitted. The proportion of patients with non severe disease was much higher than that of severe new crown pneumonia.
The median incubation period is 4 days
According to the research team, the incubation period is mainly determined by the time when the patient reported the latest source of infection (epidemic area personnel, wild animals) and the time when symptoms (including fatigue, cough, fever, etc.) first appeared. The incubation period of the whole population is different. The median, minimum and maximum values are used to show the trend of concentration and dispersion of the incubation period.
The study found that the incubation period of one patient in severe group and one in non severe group reached 24 days. However, a careful review of the distribution of incubation period in the whole population showed that 13 cases (1.18%) had an incubation period greater than 14 days, while only 8 cases (0.73%) had an incubation period greater than 18 days. It is easy to cause misreading to evaluate the incubation period of the population only according to the minimum and maximum values.
In addition, the incubation period of patients who live in Wuhan or contact with people in Wuhan area for a long time is mostly 0 days (the contact time is calculated according to the last day); after removing these unreasonable data, the researchers recalculated and found that the latest median incubation period is 4 days. Therefore, to better represent the trend of population dispersion, the researchers determined that the interquartile interval of incubation period was 5 days (2-7 days).
Three early novel coronavirus pneumonia may reduce the mortality of Guangdong new crown pneumonia
The team also found that some of the clinical features of covid-19 were similar to those of SARS CoV. Fever and cough are the main symptoms, gastrointestinal symptoms are not common. These characteristics suggest that sars-cov-2 has different tropism compared with SARS-CoV, mers-cov and seasonal influenza.
The proportion of patients with covid-19 who did not have fever at the beginning of admission was higher than that with SARS CoV (1%) and mers cov (2%), so if the definition of monitoring cases focuses on the detection of fever, the patients without fever may be missed. Lymphopenia is common and severe in some cases, which is consistent with the results of two recent reports.
The case fatality rate (1.4%) determined in this study was lower than that reported earlier, probably due to differences in sample size and case inclusion criteria. Our results are more similar to Chinas official statistics, which show that the mortality rate of 51857 patients with covid-19 was 3.2% as of February 16, 2020. Since patients with mild illness and those without medical treatment were not included in the study, the real world mortality rate may be lower. Early isolation, early diagnosis and early treatment may play a role in reducing the mortality of covid-19 in Guangdong Province.
How to distinguish between novel coronavirus pneumonia and influenza? The team said that although sars-cov-2 and SARS CoV have higher species similarity, some clinical features can distinguish covid-19 from SARS CoV, mers CoV and seasonal influenza (please refer to the online attachment of the original paper for details). For example, seasonal influenza is more common in respiratory clinics and wards.
For the future research direction, the research team said that at present, it is urgent to clarify the dynamic characteristics of virus transmission, transmission routes, and the affinity of virus to human tissues. The novel coronavirus pneumonia epidemic trend has been studied in the past. However, it has not been properly incorporated into the governments recent strong intervention measures, the impact of the national rehabilitation, the closure of Wuhan and Huanggang on the epidemic trend of the population. Therefore, the construction and verification of intelligent prediction model of virus transmission in the population is also the focus of current work.
Zhong Nanshan: do not misread the minimum and maximum values in the incubation period
The median incubation period was 4 days (interquartile range, 2-7), and 24 days in each group. However, the team believes that it is easy to misread a populations incubation period simply based on the minimum and maximum values.
Zhongnanshan teams latest paper: case fatality rate is lower than the reported level
The case fatality rate we determined (1.4%) was lower than that reported recently, probably due to differences in sample size and case inclusion criteria. Our results are more similar to Chinas official statistics, which show that the mortality rate of 51857 patients with covid-19 as of February 16, 2020 is 3.2%. As patients with mild illness and those without medical treatment are not included in this study, the real world mortality rate may be lower.