Population Modelling group, National Institute of Water and Atmospheric Research, Wellington, New Zealand.
School of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand; Manaaki Whenua, Lincoln, New Zealand.
Vaccine. 2024 Feb 27;42(6):1383-1391. doi: 10.1016/j.vaccine.2024.01.101. Epub 2024 Feb 2.
Aotearoa New Zealand implemented a Covid-19 elimination strategy in 2020 and 2021, which enabled a large majority of the population to be vaccinated before being exposed to the virus. This strategy delivered one of the lowest pandemic mortality rates in the world. However, quantitative estimates of the population-level health benefits of vaccination are lacking. Here, we use a validated mathematical model of Covid-19 in New Zealand to investigate counterfactual scenarios with differing levels of vaccine coverage in different age and ethnicity groups. The model builds on earlier research by adding age- and time-dependent case ascertainment, the effect of antiviral medications, improved hospitalisation rate estimates, and the impact of relaxing control measures. The model was used for scenario analysis and policy advice for the New Zealand Government in 2022 and 2023. We compare the number of Covid-19 hospitalisations, deaths, and years of life lost in each counterfactual scenario to a baseline scenario that is fitted to epidemiological data between January 2022 and June 2023. Our results estimate that vaccines saved 6650 (95% credible interval [4424, 10180]) lives, and prevented 74500 [51000, 115400] years of life lost and 45100 [34400, 55600] hospitalisations during this 18-month period. Making the same comparison before the benefit of antiviral medications is accounted for, the estimated number of lives saved by vaccines increases to 7604 [5080, 11942]. Due to inequities in the vaccine rollout, vaccination rates among Māori were lower than in people of European ethnicity. Our results show that, if vaccination rates had been equitable, an estimated 11%-26% of the 292 Māori Covid-19 deaths that were recorded in this time period could have been prevented. We conclude that Covid-19 vaccination greatly reduced health burden in New Zealand and that equity needs to be a key focus of future vaccination programmes.
新西兰于 2020 年和 2021 年实施了新冠消除战略，使绝大多数人口在接触病毒之前接种了疫苗。这一策略使新西兰成为世界上大流行死亡率最低的国家之一。然而，接种疫苗对人群健康的益处的定量估计却缺乏。在这里，我们使用在新西兰验证过的新冠数学模型，研究不同年龄和种族群体中不同疫苗接种率的反事实情景。该模型是在早期研究的基础上建立的，增加了年龄和时间依赖性病例确定、抗病毒药物的作用、改进的住院率估计以及放松控制措施的影响。该模型用于 2022 年和 2023 年为新西兰政府进行情景分析和提供政策建议。我们将每个反事实情景下的新冠住院、死亡和生命损失年数与 2022 年 1 月至 2023 年 6 月间拟合流行病学数据的基线情景进行比较。我们的结果估计，疫苗挽救了 6650 人（95%可信区间[4424，10180]）的生命，预防了 74500 人（51000，115400）的生命损失和 45100 人（34400，55600）的住院。在这 18 个月的时间里。如果不考虑抗病毒药物的益处，在疫苗接种前进行同样的比较，疫苗拯救的生命数量估计增加到 7604 人（5080，11942）。由于疫苗接种的不平等，毛利人的疫苗接种率低于欧洲裔。我们的研究结果表明，如果疫苗接种率更加公平，在此期间记录的 292 名毛利人新冠死亡人数中，估计有 11%-26%可以得到预防。我们的结论是，新冠疫苗接种大大减轻了新西兰的健康负担，公平性需要成为未来疫苗接种计划的重点。
