2022-05-24-世界卫生组织-Weekly_epidemiological_update_on_COVID-19_-_25_May_2022_19页_1mb

报告摘要

Globally, reported COVID-19 cases (3.7M, a 3% weekly decrease) and deaths (9,000+, an 11% weekly decrease) show a continued declining trend since January 2022, but this occurred amidst changes in testing strategies potentially impacting data reliability.
Regions: Americas and Western Pacific reported increases in new cases; European, African, South-East Asia, and Eastern Mediterranean regions reported decreases in new cases. Eastern Mediterranean reported a significant increase in deaths.
Cumulative data: Over 522 million confirmed cases and 6 million deaths reported globally as of 22 May 2022.

VOC Status: Omicron (dominant globally, BA.2 and its descendants BA.1.X, BA.2.X, BA.3, BA.4, BA.5) is the current dominant variant, exhibiting growth advantage in some settings.
Phenotypes: Evidence suggests Omicron variants are more transmissible; severity appears similar or slightly less than Delta. Reinfection risk is reduced following infection or vaccination. Neutralizing antibody levels and vaccine effectiveness (VE) are reduced compared to pre-Omicron variants, particularly against symptomatic and asymptomatic infection, though protection against severe disease remains reasonably high, and VE estimates vary significantly by study, vaccine, outcome, and time since vaccination.
Omicron BA.2 Characteristics: BA.2 and BA.2.X lineages are most prevalent (approx. 94% of Omicron sequences), with BA.2.12.1 at 17%. Limited data suggests BA.4, BA.5, and BA.2.12.1 spread faster in areas with prior BA.1 waves and may have less impact in areas with substantial prior BA.2 waves. High vaccination rates and prior epidemic waves influence the impact of these sublineages.
Vaccine Effectiveness (VE): VE against Omicron is reduced for all outcomes (severe, symptomatic, infection) compared to other VOCs. Booster doses significantly increase VE, especially against severe disease. Waning occurs, and protection is better against severe outcomes than symptomatic or asymptomatic infection, with VE decreasing more rapidly over time for less severe outcomes.

Americas: Increasing trend, highest cases from USA, Brazil. Deaths mostly stable.
Africa: Declining trend in cases and deaths. High cases and death rates in varying countries.
Eastern Mediterranean: Declining trend; still observed increase overall, moderate decrease in deaths. High cases from SA and others; high deaths from IR Iran and Tn.
Europe: Declining trend, high cases from Germany, Italy, Portugal. Deaths decreased slightly.
South-East Asia: Declining trend, cases peak from India, Thailand. Deaths decreasing.
Western Pacific: Increasing trend in cases over the last three weeks, highest cases from China, Japan. Deaths generally stable, some fluctuations.

Data are based on laboratory-confirmed cases and deaths reported by member states.
Interpretation requires caution due to varying testing strategies, surveillance methods, and data reporting practices and delays.
Data adjustments occur for data reconciliation, potentially affecting historical figures.