Moore Sam, Hill Edward M, Tildesley Michael J, Dyson Louise, Keeling Matt J
Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematics Institute, and School of Life Sciences, University of Warwick, Coventry, UK.
Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematics Institute, and School of Life Sciences, University of Warwick, Coventry, UK.
Lancet Infect Dis. 2021 Jun;21(6):793-802. doi: 10.1016/S1473-3099(21)00143-2. Epub 2021 Mar 18.
The dynamics of vaccination against SARS-CoV-2 are complicated by age-dependent factors, changing levels of infection, and the relaxation of non-pharmaceutical interventions (NPIs) as the perceived risk declines, necessitating the use of mathematical models. Our aims were to use epidemiological data from the UK together with estimates of vaccine efficacy to predict the possible long-term dynamics of SARS-CoV-2 under the planned vaccine rollout.
In this study, we used a mathematical model structured by age and UK region, fitted to a range of epidemiological data in the UK, which incorporated the planned rollout of a two-dose vaccination programme (doses 12 weeks apart, protection onset 14 days after vaccination). We assumed default vaccine uptake of 95% in those aged 80 years and older, 85% in those aged 50-79 years, and 75% in those aged 18-49 years, and then varied uptake optimistically and pessimistically. Vaccine efficacy against symptomatic disease was assumed to be 88% on the basis of Pfizer-BioNTech and Oxford-AstraZeneca vaccines being administered in the UK, and protection against infection was varied from 0% to 85%. We considered the combined interaction of the UK vaccination programme with multiple potential future relaxations (or removals) of NPIs, to predict the reproduction number (R) and pattern of daily deaths and hospital admissions due to COVID-19 from January, 2021, to January, 2024.
We estimate that vaccination alone is insufficient to contain the outbreak. In the absence of NPIs, even with our most optimistic assumption that the vaccine will prevent 85% of infections, we estimate R to be 1·58 (95% credible intervals [CI] 1·36-1·84) once all eligible adults have been offered both doses of the vaccine. Under the default uptake scenario, removal of all NPIs once the vaccination programme is complete is predicted to lead to 21 400 deaths (95% CI 1400-55 100) due to COVID-19 for a vaccine that prevents 85% of infections, although this number increases to 96 700 deaths (51 800-173 200) if the vaccine only prevents 60% of infections. Although vaccination substantially reduces total deaths, it only provides partial protection for the individual; we estimate that, for the default uptake scenario and 60% protection against infection, 48·3% (95% CI 48·1-48·5) and 16·0% (15·7-16·3) of deaths will be in individuals who have received one or two doses of the vaccine, respectively.
For all vaccination scenarios we investigated, our predictions highlight the risks associated with early or rapid relaxation of NPIs. Although novel vaccines against SARS-CoV-2 offer a potential exit strategy for the pandemic, success is highly contingent on the precise vaccine properties and population uptake, both of which need to be carefully monitored.
National Institute for Health Research, Medical Research Council, and UK Research and Innovation.
2019冠状病毒病（SARS-CoV-2）疫苗接种动态因年龄相关因素、感染水平变化以及随着感知风险下降非药物干预措施（NPIs）的放宽而变得复杂，因此需要使用数学模型。我们的目的是利用英国的流行病学数据以及疫苗效力估计值，预测在计划的疫苗推广下SARS-CoV-2可能的长期动态。
在本研究中，我们使用了一个按年龄和英国地区构建的数学模型，该模型拟合了英国一系列流行病学数据，纳入了两剂疫苗接种计划的计划推广（两剂间隔12周，接种后14天开始产生保护作用）。我们假设80岁及以上人群的默认疫苗接种率为95%，50 - 79岁人群为85%，18 - 49岁人群为75%，然后分别进行乐观和悲观的接种率变化假设。基于英国正在接种的辉瑞 - 生物科技公司和牛津 - 阿斯利康公司的疫苗，假设针对有症状疾病的疫苗效力为88%，针对感染的保护率在0%至85%之间变化。我们考虑了英国疫苗接种计划与未来多种潜在的NPIs放宽（或取消）的综合相互作用，以预测2021年1月至2024年1月期间因COVID - 19导致的再生数（R）以及每日死亡和住院模式。
我们估计仅靠疫苗接种不足以控制疫情。在没有NPIs的情况下，即使我们最乐观地假设疫苗能预防85%的感染，我们估计一旦所有符合条件的成年人都接种了两剂疫苗，R值将为1.58（95%可信区间[CI] 1.36 - 1.84）。在默认接种率情况下，对于一种能预防85%感染的疫苗，预计在疫苗接种计划完成后取消所有NPIs将导致21400例因COVID - 19死亡（95% CI 1400 - 55100），不过如果疫苗仅能预防60%的感染，这个数字将增至96700例死亡（51800 - 173200）。尽管疫苗接种大幅减少了总死亡人数，但它只为个体提供部分保护；我们估计，在默认接种率情况和60%的感染保护率下，分别有48.3%（95% CI 48.1 - 48.5）和16.0%（15.7 - 16.3）的死亡将发生在已接种一剂或两剂疫苗的个体中。
对于我们研究的所有疫苗接种情况，我们的预测突出了过早或迅速放宽NPIs所带来的风险。尽管新型SARS-CoV-2疫苗为疫情提供了一种潜在的应对策略，但成功高度取决于精确的疫苗特性和人群接种率，这两者都需要仔细监测。
英国国家卫生研究院、医学研究理事会和英国研究与创新署。
