Since the emergence of SARS-CoV-2 (COVID-19), there have been multiple waves of infection and multiple rounds of vaccination rollouts. Both prior infection and vaccination can prevent future infection and reduce severity of outcomes, combining to form hybrid immunity against COVID-19 at the individual and population level. Here, we explore how different combinations of hybrid immunity affect the size and severity of near-future Omicron waves. To investigate the role of hybrid immunity, we use an agent-based model of COVID-19 transmission with waning immunity to simulate outbreaks in populations with varied past attack rates and past vaccine coverages, basing the demographics and past histories on the World Health Organization Western Pacific Region. We find that if the past infection immunity is high but vaccination levels are low, then the secondary outbreak with the same variant can occur within a few months after the first outbreak; meanwhile, high vaccination levels can suppress near-term outbreaks and delay the second wave. Additionally, hybrid immunity has limited impact on future COVID-19 waves with immune-escape variants. Enhanced understanding of the interplay between infection and vaccine exposure can aid anticipation of future epidemic activity due to current and emergent variants, including the likely impact of responsive vaccine interventions.

中文翻译：

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模拟混合免疫对未来 COVID-19 流行浪潮的影响

自 SARS-CoV-2 (COVID-19) 出现以来，出现了多波感染和多轮疫苗接种。先前的感染和疫苗接种都可以预防未来的感染并降低结果的严重程度，结合起来在个人和群体水平上形成针对 COVID-19 的混合免疫。在这里，我们探讨了混合免疫的不同组合如何影响近期 Omicron 波的大小和严重程度。为了研究混合免疫的作用，我们使用基于病原体的 COVID-19 传播模型（免疫力减弱）来模拟过去发病率和疫苗覆盖率不同的人群中的疫情暴发，并以世界卫生组织西方国家的人口统计数据和过去的历史为基础太平洋地区。我们发现，如果过去的感染免疫力较高，但疫苗接种水平较低，那么在第一次爆发后的几个月内，可能会出现相同变种的二次爆发；同时，高疫苗接种水平可以抑制近期疫情爆发并推迟第二波疫情。此外，混合免疫对未来具有免疫逃逸变体的 COVID-19 浪潮的影响有限。加强对感染和疫苗暴露之间相互作用的了解可以帮助预测由于当前和新出现的变异而导致的未来流行病活动，包括反应性疫苗干预措施可能产生的影响。