MITRE Corporation, 202 Burlington Rd., Bedford, MA, 01730-1420, USA.
Harvey Mudd College, Mathematics, 301 Platt Blvd., Claremont, CA, 91711, USA.
Public Health. 2024 Aug;233:164-169. doi: 10.1016/j.puhe.2024.05.011. Epub 2024 Jun 19.
The purpose of this work is to characterize scenarios under which it may be in a donor country's own public health interests to donate vaccine doses to another country before its own population has been fully vaccinated. In these scenarios, vaccinating other countries can delay the evolution of new variants of the virus, decrease total deaths, and, in some cases, decrease deaths in the donor countries.
We simulate the effects of different vaccine donation policies using an epidemiological model employing COVID-19 transmission parameters.
We use the epidemiological model of Holleran et al. that incorporates virus mutation to simulate epidemic progression and estimate numbers of deaths arising from several vaccine allocation policies (donor-first, non-donor-first, and vaccine sharing) across a number of scenarios. We analyze the results in light of herd immunity limits derived in Holleran et al.
We identify realistic scenarios under which a donor country prefers to donate vaccines before distributing them locally in order to minimize local deaths during a pandemic. We demonstrate that a non-donor-first vaccination policy can delay, sometimes dramatically, the emergence of more-contagious variants. Even more surprising, donating all vaccines is sometimes better for the donor country than a sharing policy in which half of the vaccines are donated, and half are retained because of the impact donation can have on delaying the emergence of a more contagious virus. Non-donor-first vaccine allocation is optimal in scenarios in which the local health impact of the vaccine is limited or when delaying the emergence of a variant is especially valuable.
In all cases, we find that vaccine distribution is not a zero-sum game between donor and non-donor countries, illustrating the general moral reasons to donate vaccines. In some cases, donor nations can also realize local health benefits from donating vaccines. The insights yielded by this framework can be used to guide equitable vaccine distribution in future pandemics.
本研究旨在分析在何种情况下，向其他国家捐赠疫苗可能符合捐赠国自身的公共卫生利益，即在其国内人口完全接种疫苗之前。在这些情况下，向其他国家接种疫苗可以延缓病毒新变种的出现，减少总死亡人数，并且在某些情况下减少捐赠国的死亡人数。
我们使用包含 COVID-19 传播参数的传染病模型来模拟不同的疫苗捐赠政策的效果。
我们使用 Holleran 等人的传染病模型，该模型纳入了病毒突变，以模拟传染病的进展，并根据几种疫苗分配政策（捐赠国优先、非捐赠国优先和疫苗共享）在多种情况下估算死亡人数。我们根据 Holleran 等人得出的群体免疫限制来分析结果。
我们确定了一些现实情况下，捐赠国为了在大流行期间尽量减少当地死亡人数，可能会选择在国内分配疫苗之前先捐赠疫苗。我们表明，非捐赠国优先的疫苗接种政策可以延迟，有时甚至可以显著延迟更具传染性的变种的出现。更令人惊讶的是，在某些情况下，捐赠所有疫苗比一半疫苗捐赠、一半保留的共享政策对捐赠国更有利，因为捐赠可以延迟更具传染性病毒的出现。在疫苗对当地健康影响有限或延迟变种出现特别有价值的情况下，非捐赠国优先的疫苗分配是最优的。
在所有情况下，我们发现疫苗分配不是捐赠国和非捐赠国之间的零和博弈，这说明了向其他国家捐赠疫苗的普遍道德理由。在某些情况下，捐赠国也可以从捐赠疫苗中获得当地的健康益处。该框架产生的见解可用于指导未来大流行期间的公平疫苗分配。
