RESUMO
ObjectiveTo investigate the epidemiological characteristics and analyze the incidence trend of SARS-CoV-2 infection in Shanghai， China， and compare with the characteristics of the infection in Jilin Province of China during the same period in 2022 and Wuhan at the beginning of 2020. MethodsInformation of new locally-transmitted confirmed SARS-CoV-2 cases， imported confirmed COVID-19 cases， local asymptomatic SARS-CoV-2 carriers and imported asymptomatic SARS-CoV-2 carriers in Shanghai from March 1 to April 18， 2022 was collected for descriptive analysis. ResultsFrom March 1 to April 18， 2022， a total of 397 933 locally-transmitted SARS-CoV-2 cases were reported in Shanghai. Of those， 27 613 were clinically confirmed cases and 21 were severe cases. Ten deaths were related to COVID-19. The pathogen is Omicron variant BA.2 of SARS-CoV-2. The number of the infected subjects increased rapidly after March 24 and lead to a disease outbreak. Severe and deceased cases had severe comorbidity and were mostly unvaccinated with SARS-CoV-2 vaccines. Asymptomatic SARS-CoV-2 carriers accounted for 93.06%， which is significantly higher than that in Jilin Province during the same period （48.07%， P<0.001）. Daily increase in the number of clinically confirmed COVID-19 cases in Shanghai in 2022 was much lower than that in Wuhan， Hubei Province， in 2020. Number of daily newly imported confirmed COVID-19 cases and imported asymptomatic SARS-CoV-2 carriers declined during this period. ConclusionThe Omicron variant in Shanghai 2022 is highly infectious and less pathogenic. Omicron variant BA.2 replicates rapidly in asymptomatic carriers， which makes the carriers the major source of infection. Full-term vaccination of inactivated SARS-CoV-2 vaccine might decrease the pathogenicity and fatality of SARS-CoV-2 variants. SARS-CoV-2 of the Omicron BA2 strain is likely transmitted through aerosols and droplets， which poses a great challenge to the control of the COVID-19 pandemic in large cities with high population density and sophisticated public transportation.
RESUMO
ObjectiveTo assess the effects of countermeasures against coronavirus disease 2019 （COVID-19） in Shanghai from March to May 2022 in comparison with epidemiological trend of COVID-19 in New York City. MethodsDaily confirmed cases， asymptomatic SARS-CoV-2 carriers， and daily deaths were obtained in the Shanghai Municipal Health Commission and the Center for Disease Control and Prevention （CDC） of the United States. Descriptive study was conducted by using these data. ResultsFrom March 1 to May 17， the number of daily asymptomatic SARS-CoV-2 infections in Shanghai was up to 58 times as large as that of daily confirmed cases； however， the number of daily confirmed cases in Shanghai was generally less than that in New York in the same time period. At the peak of the COVID-19 epidemic， the growth of daily attack rate in Shanghai was significantly lower than that in New York （P<0.05）. Moreover， the number of daily death was evidently less than that in New York. In addition， the vaccination rate in the elderly （aged ≥60 years） in Shanghai was evidently lower than that in New York （aged ≥65 years）. ConclusionThe COVID-19 epidemics in Shanghai from March to May 2022 and in New York after December 2021 were both caused by the Omicron variant. Compared with the Delta variant， the Omicron variant has stronger replication ability and infectivity， resulting in challenges to the containment of the epidemic in metropolis such as Shanghai and New York City. The epidemic in New York City remained crucial due to absence of effective countermeasures， while that in Shanghai has been effectively contained with strict countermeasures. The prevention and control strategies may be adjusted along with the continual evolution of SARS-CoV-2 and increasing trend of imported COVID-19 cases.