Objective:To investigate a cluster epidemic of COVID-19 after a mass gathering activity in Ningbo of Zhejiang province and analyze the transmission chain and status of infection cases of different generations.Methods:The tracking of all the close contacts of the first COVID-19 case and epidemiological investigation were conducted on January 29, 2020 after a cluster epidemic of COVID-19 related with a Buddhism rally on January 19 (the 1.19 rally) in Ningbo occurred. The swabs of nose/throat of the cases and close contacts were collected and tested for nucleic acids by real-time fluorescence quantitative RT-PCR.Results:From January 26 to February 20, 2020, a total of 67 COVID-19 cases and 15 asymptomatic infection cases related with the 1.19 rally were reported in Ningbo. The initial case was the infection source who infected 29 second generation cases and 4 asymptomatic infection cases, in whom 23 second generation cases and 3 asymptomatic infection cases once took bus with the initial case, the attack rate was 33.82% (23/68) and the infection rate was 38.24% (26/68). The risks of suffering from COVID-19 and being infected were 28.91 times and 26.01 times higher in rally participants taking bus with initial case compared with those taking no bus with initial case. In this epidemic, 37 third+generation cases and 11 related asymptomatic infection cases occurred, the attack rate was 2.88% (37/1 283) and the infection rate was 4.76% (48/1 008). The main transmission routes included vehicle sharing and family transmission.Conclusion:It was a cluster epidemic of COVID-19 caused by a super spreader in a massive rally. The epidemic has been under effective control.

To explore the association between particulate matter (PM) and daily hospital visits of coronary heart diseases in Ningbo.Daily data of hospital visits from January 2014 to June 2015 (516 days in total) were obtained from the Yinzhou Health Information System in Ningbo. Daily air pollution data for PM and meteorological data were collected from the database of Ningbo Environmental Monitoring Center and Ningbo Meteorological Bureau. Time-series analysis by quasi-Poisson generalized additive model was used to examine the association between air pollution and hospital visits for coronary heart diseases by adjustment of long-term trends, seasonal patterns and meteorological variables (temperature, humidity), and day of week.An increase of an IQR of PMaccounted for 1.98% (95%:-0.59%-4.63%) increase of hospital visits for coronary heart diseases. The associations between PMand hospital visits for coronary heart diseases among female and the elderly (≥75 years) were stronger (=2.70%,95%:0.01%-5.47%;=3.35%, 95%0.12%-6.69%). The effects of PMattenuated after adjustment for PMPMhad short-term effects on daily hospital visits for coronary heart diseases in Ningbo, and such association was stronger among female and the elderly.
Age Factors ; Aged ; Air Pollutants ; adverse effects ; Air Pollution ; adverse effects ; statistics & numerical data ; China ; epidemiology ; Coronary Artery Disease ; epidemiology ; Female ; Hospitals ; utilization ; Humans ; Humidity ; adverse effects ; Male ; Middle Aged ; Particulate Matter ; adverse effects ; Seasons ; Sex Factors ; Temperature ; Time Factors