Tan Sophia T, Rodríguez-Barraquer Isabel, Kwan Ada T, Blumberg Seth, Park Hailey J, Hutchinson Justine, Leidner David, Lewnard Joseph A, Sears David, Lo Nathan C
Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, USA.
Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco, CA, USA.
Nat Commun. 2025 Jan 29;16(1):1090. doi: 10.1038/s41467-024-55029-9.
Early investigation revealed a reduced risk of SARS-CoV-2 infection among social contacts of COVID-19 vaccinated individuals, referred to as indirect protection. However, indirect protection from SARS-CoV-2 infection-acquired immunity and its comparative strength and durability to vaccine-derived indirect protection in the current epidemiologic context of high levels of vaccination, prior infection, and novel variants are not well characterized. Here, we show that both vaccine-derived and infection-acquired immunity independently yield indirect protection to close social contacts with key differences in their strength and waning. Analyzing anonymized SARS-CoV-2 surveillance data from 9,625 residents in California state prisons from December 2021 to December 2022, we find that vaccine-derived indirect protection against Omicron SARS-CoV-2 infection is strongest within three months of COVID-19 vaccination [30% (95% confidence interval: 20-38%)] with subsequent modest protection. Infection-acquired immunity provides 38% (24-50%) indirect protection for 6 months after SARS-CoV-2 infection, with moderate indirect protection persisting for over one year. Variant-targeted vaccines (bivalent formulation including Omicron subvariants BA.4/BA.5) confer strong indirect protection for at least three months [40% (3-63%)]. These results demonstrate that both vaccine-derived and infection-acquired immunity can reduce SARS-CoV-2 transmission which is important for understanding long-term transmission dynamics and can guide public health intervention, especially in high-risk environments such as prisons.
早期调查显示，在接种新冠疫苗个体的社会接触者中，感染严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的风险降低，这被称为间接保护。然而，在当前疫苗接种率高、既往感染率高和出现新变种的流行病学背景下，SARS-CoV-2感染获得性免疫产生的间接保护及其与疫苗衍生间接保护相比的强度和持久性尚未得到充分表征。在这里，我们表明，疫苗衍生免疫和感染获得性免疫均能独立地为密切社会接触者提供间接保护，但其强度和减弱情况存在关键差异。通过分析2021年12月至2022年12月加利福尼亚州监狱9625名居民的匿名SARS-CoV-2监测数据，我们发现，疫苗衍生的针对奥密克戎SARS-CoV-2感染的间接保护在新冠疫苗接种后的三个月内最强[30%（95%置信区间：20-38%）]，随后保护作用适度减弱。感染获得性免疫在SARS-CoV-2感染后的6个月内提供38%（24-50%）的间接保护，中等程度的间接保护持续超过一年。针对变种的疫苗（包括奥密克戎亚型BA.4/BA.5的二价制剂）可提供至少三个月的强烈间接保护[40%（3-63%）]。这些结果表明，疫苗衍生免疫和感染获得性免疫均可减少SARS-CoV-2传播，这对于理解长期传播动态以及指导公共卫生干预措施非常重要，尤其是在监狱等高风险环境中。
