Department of Infection Control and Preparedness, Norwegian Institute of Public Health, Postboks 222 Skøyen, 0213, Oslo, Norway.
Department of Microbiology, Oslo University Hospital, Oslo, Norway.
BMC Med. 2022 Sep 2;20(1):278. doi: 10.1186/s12916-022-02480-4.
COVID-19 vaccines have been crucial in the pandemic response and understanding changes in vaccines effectiveness is essential to guide vaccine policies. Although the Delta variant is no longer dominant, understanding vaccine effectiveness properties will provide essential knowledge to comprehend the development of the pandemic and estimate potential changes over time.
In this population-based cohort study, we estimated the vaccine effectiveness of Comirnaty (Pfizer/BioNTech; BNT162b2), Spikevax (Moderna; mRNA-1273), Vaxzevria (AstraZeneca; ChAdOx nCoV-19; AZD1222), or a combination against SARS-CoV-2 infections, hospitalisations, intensive care admissions, and death using Cox proportional hazard models, across different vaccine product regimens and age groups, between 15 July and 31 November 2021 (Delta variant period). Vaccine status is included as a time-varying covariate and all models were adjusted for age, sex, comorbidities, county of residence, country of birth, and living conditions. Data from the entire adult Norwegian population were collated from the National Preparedness Register for COVID-19 (Beredt C19).
The overall adjusted vaccine effectiveness against infection decreased from 81.3% (confidence interval (CI): 80.7 to 81.9) in the first 2 to 9 weeks after receiving a second dose to 8.6% (CI: 4.0 to 13.1) after more than 33 weeks, compared to 98.6% (CI: 97.5 to 99.2) and 66.6% (CI: 57.9 to 73.6) against hospitalisation respectively. After the third dose (booster), the effectiveness was 75.9% (CI: 73.4 to 78.1) against infection and 95.0% (CI: 92.6 to 96.6) against hospitalisation. Spikevax or a combination of mRNA products provided the highest protection, but the vaccine effectiveness decreased with time since vaccination for all vaccine regimens.
Even though the vaccine effectiveness against infection waned over time, all vaccine regimens remained effective against hospitalisation after the second vaccine dose. For all vaccine regimens, a booster facilitated recovery of effectiveness. The results from this support the use of heterologous schedules, increasing flexibility in vaccination policy.
COVID-19 疫苗在大流行应对中至关重要，了解疫苗效力的变化对于指导疫苗政策至关重要。尽管 Delta 变体不再占主导地位，但了解疫苗效力特性将提供必要的知识，以了解大流行的发展并估计随时间的潜在变化。
在这项基于人群的队列研究中，我们使用 Cox 比例风险模型估计了 Comirnaty（辉瑞/生物技术；BNT162b2）、Spikevax（莫德纳；mRNA-1273）、Vaxzevria（阿斯利康；ChAdOx nCoV-19；AZD1222）或组合疫苗对 SARS-CoV-2 感染、住院、重症监护入院和死亡的疫苗效力，针对不同的疫苗产品方案和年龄组，时间范围为 2021 年 7 月 15 日至 11 月 31 日（Delta 变体期间）。疫苗状况作为时变协变量包含在内，所有模型均根据年龄、性别、合并症、居住地县、出生地和生活条件进行调整。从整个成年挪威人口中，从 COVID-19 国家准备登记册（Beredt C19）中收集了数据。
与第二次接种后 2 至 9 周相比，第二次接种后 33 周以上，针对感染的总体调整后疫苗效力从 81.3%（置信区间（CI）：80.7 至 81.9）下降至 8.6%（CI：4.0 至 13.1）。住院分别为 98.6%（CI：97.5 至 99.2）和 66.6%（CI：57.9 至 73.6）。第三次（加强）接种后，针对感染的效力为 75.9%（CI：73.4 至 78.1），针对住院的效力为 95.0%（CI：92.6 至 96.6）。Spikevax 或 mRNA 产品的组合提供了最高的保护，但所有疫苗方案的疫苗效力都随时间推移而下降。
尽管疫苗对感染的效力随时间推移而减弱，但所有疫苗方案在第二次疫苗接种后仍能有效预防住院。对于所有疫苗方案，加强针都有助于恢复效力。这些结果支持使用异源方案，增加疫苗接种政策的灵活性。
