Dell'Antonio Cristiano Soares da Silva, Bierrenbach Ana Luiza
Instituto de Ensino e Pesquisa, Hospital Sírio-Libanês, São Paulo, São Paulo, Brazil.
Secretaria de Estado da Saúde do Espírito Santo, Núcleo Especial de Vigilância Epidemiológica, Instituto Capixaba de Ensino, Pesquisa e Inovação, Vitória, Espírito Santo, Brazil.
PLoS One. 2025 Sep 10;20(9):e0331771. doi: 10.1371/journal.pone.0331771. eCollection 2025.
Reinfections with SARS-CoV-2 have gained increasing relevance in the context of emerging immune-evasive variants and waning population immunity. Understanding their frequency and distribution is essential to guide public health strategies, particularly in middle-income countries. This study investigates the epidemiological patterns of SARS-CoV-2 reinfections in Espírito Santo, Brazil, using integrated notification and vaccination databases.
We conducted a retrospective population-based study using state-level surveillance and immunization data from September 2020 to February 2023. Deterministic record linkage was performed to identify reinfections based on four hierarchical definitions, all requiring a minimum 90-day interval between episodes. Reinfection rates were analyzed by demographic, temporal, regional, and vaccination-related variables. Specific contexts such as Indigenous communities and long-term care facilities were also explored.
Reinfection estimates varied widely depending on the definition used-from 0.27% under the strictest criteria to 9.72% under the most inclusive. Reinfections were more common among women and adults aged 30-49 years. The highest proportions occurred during the second and fourth waves, driven by the Gamma and Omicron variants, respectively. Reinfection rates were particularly elevated in Indigenous communities (16.5%) and long-term care facilities (14%), highlighting structural vulnerabilities. In contrast, no increased reinfection risk was observed among incarcerated populations, possibly due to data limitations. Reinfections were frequent among vaccinated individuals, especially those who had received two doses without boosters. However, this likely reflects exposure patterns and time since vaccination, rather than reduced vaccine effectiveness. Brazil's use of inactivated-virus vaccines, such as CoronaVac, in the early phases may also have influenced susceptibility. Reinfections occurred predominantly after the emergence of Omicron, consistent with findings from national and global studies.
This study shows that the cumulative frequency of reinfections increased over the study period, reaching up to ~10% under the most inclusive definition, while remaining modest under the strictest criteria. These findings reinforce the importance of continued genomic surveillance, timely booster campaigns, and targeted interventions in high-risk environments. The integration of multiple data sources and the use of variable reinfection definitions allowed for a nuanced analysis, offering valuable insights to inform public health planning in Brazil and similar contexts.
在出现免疫逃逸变异株和人群免疫力下降的背景下，新冠病毒再次感染的相关性日益增加。了解其频率和分布对于指导公共卫生策略至关重要，尤其是在中等收入国家。本研究利用综合通报和疫苗接种数据库，调查了巴西圣埃斯皮里图州新冠病毒再次感染的流行病学模式。
我们利用2020年9月至2023年2月的州级监测和免疫数据进行了一项基于人群的回顾性研究。基于四个层次定义进行确定性记录链接，以识别再次感染，所有定义都要求两次发病之间至少间隔90天。通过人口统计学、时间、地区和疫苗接种相关变量分析再次感染率。还探讨了土著社区和长期护理机构等特定背景。
根据所使用的定义，再次感染的估计值差异很大，从最严格标准下的0.27%到最宽松标准下的9.72%。再次感染在女性和30 - 49岁成年人中更为常见。最高比例分别出现在第二波和第四波疫情期间，分别由伽马变异株和奥密克戎变异株驱动。土著社区（16.5%）和长期护理机构（14%）的再次感染率特别高，凸显了结构上的脆弱性。相比之下，在被监禁人群中未观察到再次感染风险增加，这可能是由于数据限制。接种疫苗的个体中再次感染很常见，尤其是那些接种了两剂但未接种加强针的人。然而，这可能反映了接触模式和接种疫苗后的时间，而不是疫苗效力降低。巴西在早期阶段使用灭活病毒疫苗（如科兴疫苗）也可能影响了易感性。再次感染主要发生在奥密克戎变异株出现之后，这与国家和全球研究结果一致。
本研究表明，在研究期间再次感染的累积频率有所增加，在最宽松的定义下达到约10%，而在最严格的标准下仍然较低。这些发现强化了持续进行基因组监测、及时开展加强针接种运动以及在高风险环境中进行针对性干预措施的重要性。整合多个数据源并使用可变的再次感染定义允许进行细致入微的分析，为巴西及类似背景下的公共卫生规划提供了有价值的见解。
