[Epidemiological characteristics of mpox epidemic in Guangzhou]

Objective: To understand the epidemiological characteristics of mpox epidemic in Guangzhou and provide scientific evidence for the prevention and control of the disease. Methods: Based on the mpox surveillance system in Guangzhou, suspected mpox cases with fever and rash were reported by local hospitals at all levels to centers for disease control and prevention in Guangzhou for sampling, investigation and diagnosis. Descriptive epidemiological analysis was conducted on the clinical characteristics and treatment of the mpox cases and positive detection rate reported in Guangzhou as of 24:00 on June 23. Whole genome sequencing of the virus isolates was performed using Illumina Miniseq high-throughput sequencing platform. Results: The first mpox case in Guangzhou was reported on June 10 in 2023. As of 24:00 on June 23, a total of 25 confirmed mpox cases were reported. All the mpox cases were men with a M(Q1,Q3) of 32 (26, 36) years, the majority of the cases were MSM (96.0%). The main clinical features were rash (100.0%, 25/25), lymphadenectasis (100.0%, 25/25) and fever (52.0%, 13/25). Rash usually occurred near the genitals (88.0%, 22/25). The close contacts, mainly family members (40.4%, 23/57), showed no similar symptoms, such as fever or rash. The positive rate of mpox virus in household environment samples was 30.5%. The analyses on 3 complete gene sequences of mpox virus indicated that the strains belonged to West African type Ⅱb clade, B.1.3 lineage. Conclusions: Hidden transmission of mpox virus had occurred in MSM in Guangzhou. However, the size of affected population is relatively limited, and the possibility of wide spread of the virus is low.

[Establishment of index system for population based SARS-CoV-2 nucleic acid screening]

Objective: To establish an index system of population based SARS-CoV-2 nucleic acid screening, and provide reference to determine the screening coverage appropriately. Methods: The literature review and brain storming sessions were used to develop the basic frame and index system of population based SARS-CoV-2 nucleic acid screening. Based on Delphi method and Analytic Hierarchy Process, 21 domestic experts were selected for two rounds of consultation to determine the index system of population based SARS-CoV-2 nucleic acid screening and its weight. Results: The positive indexes of experts in two rounds of consultations were both 100%. The experts' authority coefficients (Cr) were 0.88±0.08 and 0.89±0.07, respectively. And the range of coefficient of variation (CV) were (0.08, 0.24), (0.09, 0.25). The Kendall's W coordination coefficients were 0.34 and 0.22 respectively, which were statistically significant. The index system of population based SARS-CoV-2 nucleic acid screening was established, which had 4 first-level indexes, 11 second-level indexes and 58 third-level indexes. Besides, the weight of each index was determined. Conclusion: The index system of population based SARS-CoV-2 nucleic acid screening has been established, which can provide scientific reference for the health administration to determine the coverage of population based SARS-CoV-2 nucleic acid screening when local COVID-19 epidemic occurs.

[Epidemiological characteristics of imported COVID-19 cases in Guangzhou]

Objective: To understand the epidemiological characteristics of imported COVID-19 cases in Guangzhou and provide scientific basis for the prevention and control of the disease. Methods: The data of imported COVID-19 in Guangzhou reported as of April 1, 2020 were collected from National Notifiable Disease Report System of China. The software Excel 2010 and SPSS 19.0 were applied for data cleaning and statistical analysis. Results: As of April 1, 2020, a total of 103 imported COVID-19 cases had been reported in Guangzhou, in which 92 were confirmed cases and 11 were asymptomatic infection cases. The number of the confirmed imported cases accounted for 11.4% (92/806) in of the total in China at the same time. The male to female ratio of the cases was 1.58∶1 (63∶40). The median age of the cases was 31 years (P(25)-P(75):22-40 years), range of age was 11-63 years. The main occupational distributions of the cases were business services (41/103, 39.8%) and students (36/103, 35.0%). The imported cases whose destinations were 19 provinces and municipalities rather than Guangdong after entering the country accounted for 43.7%. The main source countries of infections were the United Kingdom (27/103, 26.2%), the Philippines (13/103, 12.6%), the United States (13/103, 12.6%) and Nigeria (7/103, 6.8%). There were 34 inbound flights from which the imported COVID-19 cases were detected, in which 10 flights (10/34, 29.4%) were found to carry more than 3 cases, with an average voyage time of (11.14±0.53) hours. A total of 29 imported cases(28.2%) showed symptoms before entering the country, and 65 cases (63.1%) had been isolated before the onset of the disease. The mean free activity time of the isolated cases after the onset was (6.76±0.79) days. The average number of the imported cases' close contacts was 53. There were 13 clusters of COVID-19 caused by the imported cases, involving 36 cases (including 1 imported associated case). Conclusions: The sources of the imported COVID-19 cases in Guangzhou were widely distributed, and no cases had been found to be infected on the flights. In the early stage of the imported epidemic, there was high risk for the spread of the epidemic. Strengthened prevention and control of imported COVID-19 effectively reduced the of transmission risk of COVID-19 in communities.