ABSTRACT
INTRODUCTION: We analysed case-contact clusters during the Omicron BA.2 epidemic in Shanghai to assess the risk of infection of contacts in different settings and to evaluate the effect of demographic factors on the association of infectivity and susceptibility to the Omicron variant. METHODS: Data on the settings and frequency of contact, demographic characteristics and comorbidities of index cases, contacts and secondary cases were analysed. Independent effect of multiple variables on the risk for transmission and infection was evaluated using generalised estimating equations. RESULTS: From 1 March to 1 June 2022, we identified 450 770 close contacts of 90 885 index cases. The risk for infection was greater for contacts in farmers' markets (fixed locations where farmers gather to sell products, adjusted OR (aOR): 3.62; 95% CI 2.87 to 4.55) and households (aOR: 2.68; 95% CI 2.15 to 3.35). Children (0-4 years) and elderly adults (60 years and above) had higher risk for infection and transmission. During the course of the epidemic, the risk for infection and transmission in different age groups initially increased, and then decreased on about 21 April (17th day of citywide home quarantine). Compared with medical workers (reference, aOR: 1.00), unemployed contacts (aOR: 1.77; 95% CI 1.53 to 2.04) and preschoolers (aOR: 1.61; 95% CI 1.26 to 2.05) had the highest risk for infection; delivery workers (aOR: 1.90, 95% CI 1.51 to 2.40) and public service workers (aOR: 1.85; 95% CI 1.64 to 2.10) had the highest risk for transmission. Contacts who had comorbidities (aOR: 1.10; 95% CI 1.09 to 1.12) had a higher risk for infection, particularly those with lung diseases or immune deficiency. CONCLUSION: Farmers' markets and households were the main setting for transmission of Omicron. Children, the elderly, delivery workers and public service workers had the highest risk for transmission and infection. These findings should be considered when implementing targeted interventions.
Subject(s)
COVID-19 , Epidemics , Adult , Child , Aged , Humans , SARS-CoV-2 , China/epidemiologyABSTRACT
Nitrite-dependent anaerobic methane oxidation (n-damo) process can play an important role in the methane mitigation in the environment. However, the distribution of n-damo organisms in freshwater sediment ecosystem and the associated environmental factors remain essentially unclear. The present study investigated the temporal and spatial dynamics of sediment n-damo community in the freshwater Dongjiang River using quantitative PCR assay and clone library analysis targeting n-damo pmoA gene. Sediment samples were collected at nine locations along the Dongjiang River in May and August in 2015. The remarkable temporal and spatial changes of sediment n-damo community abundance, richness, diversity, and structure occurred in the Dongjiang River and its tributaries. The n-damo pmoA gene in sediments of the Dongjiang River and its tributaries varied from 9.07 × 104 to 3.02 × 106 copies per gram dry sediment. Compared to the stem of the Dongjiang River, tributaries had relatively higher sediment n-damo community size. Sediment n-damo community abundance was higher in August than in May, while an opposite trend was observed for n-damo community richness and diversity. Sediment n-damo community structure showed a great difference between in May and August. Sediment nitrite nitrogen content was positively correlated to n-damo community abundance, but negatively to richness and diversity. Ammonia nitrogen content showed a positive correlation to n-damo community abundance, while n-damo community diversity was negatively correlated to the ratio of total organic carbon to total nitrogen (C/N). In addition, nitrite nitrogen as well as C/N might influence n-damo community structure.
