Expert review of global real-world data on COVID-19 vaccine booster effectiveness and safety during the omicron-dominant phase of the pandemic

COVID-19 vaccines have been highly effective in reducing morbidity and mortality during the pandemic. However, the emergence of the Omicron variant and subvariants as the globally dominant strains have raised doubts about the effectiveness of currently available vaccines and prompted debate about potential future vaccination strategies. Using the publicly available IVAC VIEW-hub platform, we reviewed 52 studies on vaccine effectiveness (VE) after booster vaccinations. VE were reported for SARS-CoV-2 symptomatic infection, severe disease and death and stratified by vaccine schedule and age. In addition, a non-systematic literature review of safety was performed to identify single or multi-country studies investigating adverse event rates for at least two of the currently available COVID-19 vaccines. Booster shots of the current COVID-19 vaccines provide consistently high protection against Omicron-related severe disease and death. Additionally, this protection appears to be conserved for at least 3 months, with a small but significant waning after that. The positive risk-benefit ratio of these vaccines is well established, giving us confidence to administer additional doses as required. Future vaccination strategies will likely include a combination of schedules based on risk profile, as overly frequent boosting may be neither beneficial nor sustainable for the general population.

新冠疫苗（COVID-19 vaccines）在新冠大流行期间对降低发病率与死亡率成效显著。然而，奥密克戎变异株及其亚变异株成为全球主流毒株后，现有疫苗的保护效力引发了学界质疑，也引发了关于未来潜在接种策略的讨论。本研究依托公开可用的IVAC VIEW-hub平台，回顾了52项关于加强针接种后疫苗有效性（vaccine effectiveness, VE）的研究。相关研究报告了针对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）有症状感染、重症及死亡的疫苗保护效力，并按疫苗接种程序与年龄进行了分层分析。此外，本研究还开展了一项非系统性文献综述，旨在筛选出至少针对两款现有新冠疫苗开展不良事件发生率研究的单国或多国研究。当前新冠疫苗的加强针，对奥密克戎相关重症及死亡始终提供高水平保护。此外，该保护效力至少可维持3个月，此后仅会出现小幅但显著的衰减。此类疫苗积极的风险收益比已得到充分证实，这让我们有信心按需追加接种剂量。未来的接种策略或许会结合个体风险轮廓制定接种程序，因为过于频繁的加强针接种对于普通人群而言既无额外益处，也不具备可持续性。