Course of disease and related epidemiological parameters of COVID-19: a prospective study based on contact tracing cohort / 中华预防医学杂志

Objective: To analyze the course of disease and epidemiological parameters of COVID-19 and provide evidence for making prevention and control strategies. Methods: To display the distribution of course of disease of the infectors who had close contacts with COVID-19 cases from January 1 to March 15, 2020 in Guangdong Provincial, the models of Lognormal, Weibull and gamma distribution were applied. A descriptive analysis was conducted on the basic characteristics and epidemiological parameters of course of disease. Results: In total, 515 of 11 580 close contacts were infected, with an attack rate about 4.4%, including 449 confirmed cases and 66 asymptomatic cases. Lognormal distribution was fitting best for latent period, incubation period, pre-symptomatic infection period of confirmed cases and infection period of asymptomatic cases; Gamma distribution was fitting best for infectious period and clinical symptom period of confirmed cases; Weibull distribution was fitting best for latent period of asymptomatic cases. The latent period, incubation period, pre-symptomatic infection period, infectious period and clinical symptoms period of confirmed cases were 4.50 (95%CI:3.86-5.13) days, 5.12 (95%CI:4.63-5.62) days, 0.87 (95%CI:0.67-1.07) days, 11.89 (95%CI:9.81-13.98) days and 22.00 (95%CI:21.24-22.77) days, respectively. The latent period and infectious period of asymptomatic cases were 8.88 (95%CI:6.89-10.86) days and 6.18 (95%CI:1.89-10.47) days, respectively. Conclusion: The estimated course of COVID-19 and related epidemiological parameters are similar to the existing data.

Epidemiological analysis of imported cases of dengue fever in Guangdong province and Hong Kong during 2004-2006 in China / 中华流行病学杂志

Objective To analyze the epidemiological characteristics of imported cases of dengue fever in Guangdong province (GD) and in I-long Kong (HK) during 2004-2006 to provide evidence for further cooperation in the prevention and control programs on dengue fever in the two places.Methods Descriptive statistical analysis was performed on data obtained from dengue fever surveillance and reporting network in GD and from Centre for Health Protection,Department of Health,HK.Results Both from GD and HK 44 and 93 imported cases of Dengue fever were reported during 2004-2006.Most patients from GD acquired their infection from Singapore (13 cases),Indonesia (9 cases) or Cambodia (6 cases) while patients in HK mainly were imported from Indonesia (31 cases),the Philippines (16 cases) and Thailand (15 cases).The peak seasons of the two places were both from July to September.During the non-peak season period,the number of cases in Hong Kong was higher than that in Guangdong.Male/ female ratio was 1.2 : 1 in GD and 1.1 : 1 in HK.Age of patients in GD appeared to range from 6-80 years,with 63.6% (28/44) of them aged 20-39 years.40.9% (18/44) of the cases were engaged in business,services,housework or unemployed.Those cases in HK were between 10-72 years of age,with 63.6%(28/44) of them aged 20-39 years while 47.3%(44/93) of the patients were with the occupation of business,services and industry.More cases in GD had a onset of disease before entering the border (27 : 17) than the cases in HK (35 : 57).The average time interval between onset and diagnosis were 7 and 9 days for GD and HK respectively.Conclusion Frequent travel between Southeast Asia in summer among the working class appeared to be the main factor,causing imported cases of dengue fever in GDand HK.It is crucial to provide health education targeted at these high risk groups in order to prevent importation of dengue fever in the two areas.

An investigation on nosocomial infection with severe acute respiratory syndrome in health-care workers at 13 key hospitals in Guangdong Province / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analysis the risk factors influencing nosocomial infection of severe acute respiratory syndrome (SARS) in health-care workers and to evaluate effectiveness of its control and preventive measures in 13 key hospitals caring for SARS patients.</p><p><b>METHODS</b>Number of SARS patients, clinical conditions of them, its attack rate in health-care workers, and characteristics of hospitals, including their environment, isolating measures, etc. were investigated at the 13 hospital in Guangzhou to analyze the risk factors influencing nosocomial infection of SARS and its attack rates in health-care workers before and after implementation of preventive measures and to evaluate their effectiveness.</p><p><b>RESULTS</b>Totally, 841 patients with SARS were treated at the 13 hospitals in Guangzhou and 285 health-care workers caring for them infected nosocomially. Attack rate in health-care workers was higher at general hospitals, hospital accepting more cases in critical conditions and hospitals with poor precautious measures, and lower in hospitals with isolated wards or areas, or department of infection, specially caring for SARS patients, and those with effective intervention measures to prevent secondary infection.</p><p><b>CONCLUSION</b>Nosocomial infection of SARS in health-care workers was affected by clinical condition of SARS patients, characteristics and environment of hospitals and their personal protective measures adopted.</p>

Effectiveness of personal protective measures in prevention of nosocomial transmission of severe acute respiratory syndrome / 中华流行病学杂志

<p><b>OBJECTIVE</b>To evaluate the effectiveness of personal protective measures of health care workers (HCWs) against severe acute respiratory syndrome (SARS).</p><p><b>METHODS</b>A case-control study from ten hospitals in Guangdong, with 180 non-infected and 77 infected staff members that accessed the isolation unit every day, and participated in direct first aid for severe SARS patients. All participants were surveyed about how they were using personal protective equipment (PPE), protective drugs and hygiene habits when caring for patients with SARS. Statistical analysis was done with either chi(2) or Fisher's exact test for univariate analysis, whereas we used forward stepwise selection (Waldesian) for logistic regression.</p><p><b>RESULTS</b>Univariate analysis showed that mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting", gargle, "membrane protection", "taking shower and changing clothing after work", "avoid from eating and drinking in ward", oseltamivir phospha tall had protective effects (P < 0.05), but stepwise logistic regression showed significant differences for mask (OR = 0.78, 95% CI: 0.60 - 0.99), goggles (OR = 0.20, 95% CI: 0.10 - 0.41) and footwear (OR = 0.58, 95% CI: 0.39 - 0.86). Analysis for linear trend in proportions showed that dose response relationship existed in mask, gown, gloves, goggles, footwear, gargle, "membrane protection" and "taking shower and changing dree after work" (P < 0.01). The attack rate of HCWs who were rescuing severe SARS patients without any PPE was 61.5% (16/26). It seemed that the more the protective measures were used, the higher the protective effect was (P < 0.001), and could reach 100% if mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting" were all used at the same time.</p><p><b>CONCLUSIONS</b>Nosocomial infection of SARS can be prevented effectively by precautions against droplets and personal contact. HCWs must take strict protection according to the guidance of WHO or Chinese MOH and pay attention to personal hygiene.</p>

An epidemiological study on the index cases of severe acute respiratory syndrome occurred in different cities among Guangdong province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the epidemiological features of the index cases of severe acute respiratory syndrome (SARS) occurred in different cities in Guangdong province and to trace for the source of infection.</p><p><b>METHODS</b>Standardized individual case inventory was adopted to conduct investigation on index cases and on persons who had close contact with index cases in Guangdong province. Data on the epidemiological characteristics, secondary cases and the links among index cases were analyzed.</p><p><b>RESULTS</b>Between November 16, 2002 and April 16, 2003, there had been 13 index cases of SARS including 3 cadres, 3 farmers, 2 retirees, 2 workers and 1 shop attendant, reported from 13 cities in Guangdong province. Between November 2002 and January 2003, there had been 7 cities reported to have identified index cases of SARS with 6 of them being infected in their own cities and 1 imported from Guangzhou city. All of the cases had no close contacts to similar patients but 6 of them later caused 2nd or even 3rd generation cases of SARS. Most cases hit young people (7/13) with a sex ratio of 1:0.6. The fatality rate of index cases was high (4/13).</p><p><b>CONCLUSION</b>No evidence showed that there was direct transmission among the index cases. Data regarding the geographical origin of those index cases led to the assumption that the infection had started in six cities of Pearl river delta region and the Hong Kong Special Administrative Region.</p>

Epidemiological study on severe acute respiratory syndrome in Guangdong province / 中华流行病学杂志

<p><b>OBJECTIVES</b>To understand the epidemiological characteristics of severe acute respiratory syndrome (SARS) outbreaks in some areas of Guangdong province and to provide scientific basis for prevention and control measures against it.</p><p><b>METHODS</b>Standardized questionnaire was used on individual cases. Data on the epidemiological characteristics as time, place, persons and aggregation status of SARS cases, development of the epidemics, were analyzed with software EPI 6.0.</p><p><b>RESULTS</b>The incidence of SARS in Guangdong province was 1.72/100,000 with case fatality rate as 3.64%. Most cases of SARS occurred between the last ten days of January and the first ten days of February with the peak (61.88% of the patients) occurred in the first ten days of February. As to the distribution of place, Pearl river delta region-economically developed with great number of mobile population-was heavily affected areas (account for 96.66% of the total patients). The majority of patients were young adults and medical staff seemed to be the most affected subgroup (account for 24.9% of the patients in total). Family and hospital aggregation of patients comprised the another two important characteristics of SARS (account for 37.1% of the total patients).</p><p><b>CONCLUSION</b>Current knowledge on SARS suggested that it was an air-borne infectious disease with human beings served as the source of infection. The incubation period of the disease was from 1 to 12 days with a median of 4 days. Respiratory secretions and close contact contributed to person-to-person transmission. Most cases were distributed in Pearl river delta region, an area famous for its economic development and heavy flow of mobile population.</p>

Severe acute respiratory syndrome in Guangdong Province of China: epidemiology and control measures / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore epidemiological features and risk factors of severe acute respiratory syndrome (SARS) in Guangdong Province of China, so as to work out effective strategies for its better control.</p><p><b>METHODS</b>A total of 1 511 clinically confirmed SARS cases in Guangdong Province of China from November 16, 2002 to Jun 15, 2003 were retrospectively analyzed.</p><p><b>RESULTS</b>The first SARS case was identified in Foshan municipality on November 16, 2002, followed by 1 511 clinically confirmed cases (including 58 deaths) up to May 15, 2003. Of all cases, health care workers and community family cluster cases accounted for 19.38% and 12.04%. 65.86% SARS patients aged 20 - 49 years, and increased incidence was positively related to their ages. 95.97% cases lived in the following five cities around Pearl Delta Area: Foshan, Guangzhou, Shenzhen, Zhongshan, and Jiangmen. Eleven early reported cases in the communities took animal-related positions. Face-to-face contacts with infected droplets were the main transmission route. An epidemic peak occurred during January 28 to February 26, and those cases accounted for 50.69% of total. Incidence, mortality, and case fatality of SARS were 1.77/100,000, 0.07/100,000, and 3.84% respectively. The mean incubation period was 4.5 days.</p><p><b>CONCLUSION</b>The most effective way to control SARS is to break the chain of transmission from infected to healthy persons-early identification, prompt and effective isolation, and vigorous close contact tracing. Hospital infections among health care workers is critical. Several observations support the hypothesis of an animal origin for the disease.</p>