RESUMEN
Objective: To analyze the epidemiological characteristics of COVID-19 cluster epidemic in Huizhou from January to February in 2020, and we provide experience and reference for the prevention and control of cluster epidemic. Methods Descriptive epidemiology was used to analyze the clusters of COVID-19 in Huizhou city. Results From January to February in 2020, a total of 19 COVID-19 cluster outbreaks were reported in Huizhou. The most common cluster outbreaks were in Huidong county (8 cases), Boluo county (3 cases) and Huiyang district (3 cases). There were 59 cases involved in 19 outbreaks, among which 46 were confirmed cases, and 13 were asymptomatic infected. The sex ratio of male to female was 0.84:1, the age was 1-85 years old. The 19 cases of outbreaks were all caused by imported cases, among which 13 cases were imported from Wuhan (68.4%), 3 cases were imported from Hubei province except Wuhan (15.8%), and 3 cases were imported from other provinces and cities (15.8%). There were 13 cases (68.4%) in the first generation, and 6 cases (31.6%) in the second generation. Events exposed place were variety, including 3 (15.8%) simple family exposure, 13 (68.4%) joint exposure, exposure family, 1 (5.26%) of the joint exposure, family exposure, family dinners, 1 (5.26%) of the joint exposure, family exposure, exposure (hotel) exposed in public places, 1 (5.26%) of the collective unit (workplace) exposure. Conclusion All the COVID - 19 cluster outbreaks in Huizhou city were caused by imported cases, most of which occurred in the family and were caused by families living together and eating together. As the number of people returning to work, production and school increases, various prevention and control measures should be implemented in key areas, key populations and key places to prevent the outbreak from rebounding.
RESUMEN
A susceptible person experiences the highest exposure risk of respiratory infection when he or she is in close proximity with an infected person. The large droplet route has been commonly believed to be dominant for most respiratory infections since the early 20th century, and the associated droplet precaution is widely known and practiced in hospitals and in the community. The mechanism of exposure to droplets expired at close contact, however, remains surprisingly unexplored. In this study, the exposure to exhaled droplets during close contact (< 2 m) via both the short-range airborne and large droplet sub-routes is studied using a simple mathematical model of expired flows and droplet dispersion/deposition/inhalation, which enables the calculation of exposure due to both deposition and inhalation. The short-range airborne route is found to dominate at most distances studied during both talking and coughing. The large droplet route only dominates when the droplets are larger than 100 m and when the subjects are within 0.2 m while talking or 0.5 m while coughing. The smaller the exhaled droplets, the more important the short-range airborne route. The large droplet route contributes less than 10% of exposure when the droplets are smaller than 50 m and when the subjects are more than 0.3 m apart, even while coughing.