Dynamic Zero-Covid strategy curtails mutagenesis and emergence of new variants of the SARS-CoV-2 (preprint)

Within the local outbreak period of SARS-CoV-2 Delta variant in Nanjing and Yangzhou, China, we analyzed the mutation process of the Delta variants in 520 cases, as well as the production, spread and elimination of new mutant strains under the non-pharmaceutical interventions (NPI) strategy. The investigation on distribution of COVID-19 cases and phylogenetic analysis of SARS-CoV-2 genome sequences attributed to tracking the transmission chains, transmission chains were terminated by the isolation of the COVID-19 patients and quarantine of close-contracts, suggesting the importance of NPI in prompting some mutations to disappear and stopping the transmission of new variants. Dynamic zero-Covid strategy has been implemented successfully to against the second-largest local epidemic caused by an imported COVID-19 case in China.

Early warning signs for severe patients with Coronavirus Disease 2019 and its epidemical significance (preprint)

Background Since December 2019 coronavirus disease 2019 (COVID-19) emerged in Wuhan city and rapidly spread throughout China. However, early warning signs for severe patients with COVID-19 were not fully known.Methods Information on admission was collected through a standard questionnaire. We described the epidemiological characteristics of the patients with COVID-19, analyzed the risk factors associated with severe illness, and estimated the key epidemiologic time-delay distributions.Results A total of 631 patients with laboratory-confirmed COVID-19 were identified. The proportion of severe cases was 8.4%. The epidemic of COVID-19 experienced four stages: sporadic phase, exponential growth phase, peak plateau phase, and declining phase. The proportion of severe cases was significantly different in four stages and 13 municipal prefectures (P < 0.001). Factors including elderly more than 65years(yrs) old, underlying medical conditions, fever patient whose highest temperature beyond 39.0℃, dyspnea, and lymphocytopenia(< 1.0 × 109/L) could possibly become the early warning signs for severe patients of COVID-19. In contrast, earlier visit to the clinic could reduce the severe risk. Besides, the viral load may be a potentially useful marker associated with disease severity of COVID-19 infection.Conclusions The epidemic experienced four stages with obviously areas difference. People aged beyond 65 yrs or underlying medical conditions once appear symptoms like fever beyond 39.0℃ and/or dyspnea should immediately visit health care.