RESUMO
Objective: To analyze the epidemiological characteristics of a local cluster of corona virus disease 2019 (COVID-19) pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2, and thus provide scientific evidence for the formulation of scientific prevention and control measures. Method: Descriptive epidemiological methods were used to analyze the causes, transmission, vaccination effects and prevention measures of 12 local clustered outbreaks in Haizhu district in March and April 2022 by retrospective investigation. Results: A total of 12 infected patients were reported, all of which were confirmed infected with SARS-CoV-2 Omicron BA.2. Clinical manifestations: 10 cases had fever (83.33%), 7 cases had sore throat (58.33%), 7 cases had cough (58.33%), 5 cases had fatigue (41.67%), and 4 cases had headache or dizziness (33.33%), 2 cases had gastrointestinal symptoms (16.67%), and 1 case had muscle soreness (8.33%). The clinical classification is as follows: 10 cases of mild disease (83.33%), 2 cases of common type (16.67%), no severe disease and no death. The earliest infection time was March 27, and the last case was April 15. The peak incidence was concentrated on April 8 and April 10, with a total of 5 cases (41.67%). The shortest incubation period was 2 days and the longest was 14 days, with an average of 6.55 days. The geographical distribution indicated that 7 cases from Yangyang Clothing Company (58.33%), 3 cases from Guangzhou No. 3 Middle School (25.00%), and 2 cases of family clusters (16.67%). The sex ratio of all patients was 1:3. The youngest age was 18 years old and the oldest was 59 years old. The 12 cases were young adults;of which, 9 cases were 21- < 60 years old (accounting for 75.00%), and 3 cases were 18- < 21 years old (25.00%). Occupational distribution;employees were accounting for 58.33%, followed by unemployed accounting for 25.00%, and students accounting for 16.67%. A 1:3+ matched case-control analysis in 58 high-risk close contacts was conducted, and found that infection and vaccination were not statistically correlated (X2 = 0.861, P > 0.05). Similarly, by conducting a 1:1+ matched case-control analysis, we failed to observed a statistically significantly in the effect of sex on infection (X2 = 0.325, P > 0.05). Conclusions: The outbreak was caused by SARS-CoV-2 Omicron BA.2;the source of infection was still unknown, and there was hidden transmission. Therefore, strengthening personal protection and giving full play to the role of medical units and pharmacies as sentinel points and industry monitoring should be necessary for the normalization of COVID-19 pneumonia prevention and control.
RESUMO
BACKGROUND: The role of fecal aerosols in the transmission of severe acute respiratory syndrome coronavirus 2 has been suspected. OBJECTIVE: To investigate the temporal and spatial distributions of 3 infected families in a high-rise apartment building and examine the associated environmental variables to verify the role of fecal aerosols. DESIGN: Epidemiologic survey and quantitative reverse transcriptase polymerase chain reaction analyses on throat swabs from the participants; 237 surface and air samples from 11 of the 83 flats in the building, public areas, and building drainage systems; and tracer gas released into bathrooms as a surrogate for virus-laden aerosols in the drainage system. SETTING: A high-rise apartment building in Guangzhou, China. PARTICIPANTS: 9 infected patients, 193 other residents of the building, and 24 members of the building's management staff. MEASUREMENTS: Locations of infected flats and positive environmental samples, and spread of virus-laden aerosols. RESULTS: 9 infected patients in 3 families were identified. The first family had a history of travel to the coronavirus disease 2019 (COVID-19) epicenter Wuhan, whereas the other 2 families had no travel history and a later onset of symptoms. No evidence was found for transmission via the elevator or elsewhere. The families lived in 3 vertically aligned flats connected by drainage pipes in the master bathrooms. Both the observed infections and the locations of positive environmental samples are consistent with the vertical spread of virus-laden aerosols via these stacks and vents. LIMITATION: Inability to determine whether the water seals were dried out in the flats of the infected families. CONCLUSION: On the basis of circumstantial evidence, fecal aerosol transmission may have caused the community outbreak of COVID-19 in this high-rise building. PRIMARY FUNDING SOURCE: Key-Area Research and Development Program of Guangdong Province and the Research Grants Council of Hong Kong.