Smith Cameron A, Yates Christian A, Ashby Ben
Department of Mathematical Sciences, University of Bath, Bath, United Kingdom.
Milner Centre for Evolution, University of Bath, Bath, United Kingdom.
PLOS Glob Public Health. 2022 Apr 26;2(4):e0000298. doi: 10.1371/journal.pgph.0000298. eCollection 2022.
The COVID-19 pandemic, caused by the coronavirus SARS-CoV-2, has led to a wide range of non-pharmaceutical interventions being implemented around the world to curb transmission. However, the economic and social costs of some of these measures, especially lockdowns, has been high. An alternative and widely discussed public health strategy for the COVID-19 pandemic would have been to 'shield' those most vulnerable to COVID-19 (minimising their contacts with others), while allowing infection to spread among lower risk individuals with the aim of reaching herd immunity. Here we retrospectively explore the effectiveness of this strategy using a stochastic SEIR framework, showing that even under the unrealistic assumption of perfect shielding, hospitals would have been rapidly overwhelmed with many avoidable deaths among lower risk individuals. Crucially, even a small (20%) reduction in the effectiveness of shielding would have likely led to a large increase (>150%) in the number of deaths compared to perfect shielding. Our findings demonstrate that shielding the vulnerable while allowing infections to spread among the wider population would not have been a viable public health strategy for COVID-19 and is unlikely to be effective for future pandemics.
由冠状病毒SARS-CoV-2引发的新冠疫情，已促使全球各地实施了一系列非药物干预措施以遏制传播。然而，其中一些措施，尤其是封锁措施，所带来的经济和社会成本高昂。针对新冠疫情，另一种广受讨论的公共卫生策略本应是“保护”那些最易感染新冠病毒的人群（尽量减少他们与他人的接触），同时让感染在低风险个体中传播，以期实现群体免疫。在此，我们使用随机易感-暴露-感染-康复（SEIR）模型框架对该策略的有效性进行回顾性探究，结果表明，即便在完美保护这一不切实际的假设条件下，医院仍会迅速不堪重负，低风险个体中会出现许多可避免的死亡病例。至关重要的是，与完美保护相比，即便保护效果仅有小幅（20%）下降，死亡人数可能也会大幅增加（超过150%）。我们的研究结果表明，保护易感染人群同时让感染在更广泛人群中传播，对于新冠疫情而言并非可行的公共卫生策略，而且对未来的疫情可能也不会有效。
