MMWR Morb Mortal Wkly Rep. 2022 Oct 21;71(42):1327-1334. doi: 10.15585/mmwr.mm7142a3.
The SARS-CoV-2 Omicron variant (B.1.1.529 or BA.1) became predominant in the United States by late December 2021 (1). BA.1 has since been replaced by emerging lineages BA.2 (including BA.2.12.1) in March 2022, followed by BA.4 and BA.5, which have accounted for a majority of SARS-CoV-2 infections since late June 2022 (1). Data on the effectiveness of monovalent mRNA COVID-19 vaccines against BA.4/BA.5-associated hospitalizations are limited, and their interpretation is complicated by waning of vaccine-induced immunity (2-5). Further, infections with earlier Omicron lineages, including BA.1 and BA.2, reduce vaccine effectiveness (VE) estimates because certain persons in the referent unvaccinated group have protection from infection-induced immunity. The IVY Network assessed effectiveness of 2, 3, and 4 doses of monovalent mRNA vaccines compared with no vaccination against COVID-19-associated hospitalization among immunocompetent adults aged ≥18 years during December 26, 2021-August 31, 2022. During the BA.1/BA.2 period, VE 14-150 days after a second dose was 63% and decreased to 34% after 150 days. Similarly, VE 7-120 days after a third dose was 79% and decreased to 41% after 120 days. VE 7-120 days after a fourth dose was 61%. During the BA.4/BA.5 period, similar trends were observed, although CIs for VE estimates between categories of time since the last dose overlapped. VE 14-150 days and >150 days after a second dose was 83% and 37%, respectively. VE 7-120 days and >120 days after a third dose was 60%and 29%, respectively. VE 7-120 days after the fourth dose was 61%. Protection against COVID-19-associated hospitalization waned even after a third dose. The newly authorized bivalent COVID-19 vaccines include mRNA from the ancestral SARS-CoV-2 strain and from shared mRNA components between BA.4 and BA.5 lineages and are expected to be more immunogenic against BA.4/BA.5 than monovalent mRNA COVID-19 vaccines (6-8). All eligible adults aged ≥18 years should receive a booster dose, which currently consists of a bivalent mRNA vaccine, to maximize protection against BA.4/BA.5 and prevent COVID-19-associated hospitalization.
2021 年 12 月下旬，SARS-CoV-2 奥密克戎变异株（B.1.1.529 或 BA.1）成为美国主要流行株（1）。此后，BA.1 于 2022 年 3 月被新兴谱系 BA.2（包括 BA.2.12.1）取代，随后是 BA.4 和 BA.5，自 2022 年 6 月下旬以来，它们已导致大多数 SARS-CoV-2 感染（1）。关于单价 mRNA COVID-19 疫苗对 BA.4/BA.5 相关住院的有效性数据有限，由于参照未接种疫苗组中的某些人具有感染诱导免疫的保护作用，因此对其解释较为复杂（2-5）。此外，包括 BA.1 和 BA.2 在内的早期奥密克戎谱系的感染会降低疫苗有效性（VE）估计值，因为在参照未接种疫苗组中某些人具有感染诱导免疫的保护作用。IVY 网络评估了在 2021 年 12 月 26 日至 2022 年 8 月 31 日期间，免疫功能正常的≥18 岁成年人中，与未接种疫苗相比，2、3 和 4 剂单价 mRNA 疫苗对 COVID-19 相关住院的有效性。在 BA.1/BA.2 期间，第二剂后 14-150 天 VE 为 63%，150 天后降至 34%。同样，第三剂后 7-120 天 VE 为 79%，120 天后降至 41%。第四剂后 7-120 天 VE 为 61%。在 BA.4/BA.5 期间，观察到类似的趋势，尽管最后一剂后不同时间类别 VE 估计值的 CI 重叠。第二剂后 14-150 天和>150 天 VE 分别为 83%和 37%。第三剂后 7-120 天和>120 天 VE 分别为 60%和 29%。第四剂后 7-120 天 VE 为 61%。即使接种了第三剂，对 COVID-19 相关住院的保护作用也会减弱。新授权的二价 COVID-19 疫苗包含来自原始 SARS-CoV-2 株和 BA.4 和 BA.5 谱系之间共享 mRNA 成分的 mRNA，预计对 BA.4/BA.5 的免疫原性比单价 mRNA COVID-19 疫苗更强（6-8）。所有符合条件的≥18 岁成年人都应接种加强针，目前加强针由二价 mRNA 疫苗组成，以最大限度地预防 BA.4/BA.5 和预防 COVID-19 相关住院。
Zotero 插件