Oliveira Monike Aparecida Matos de, Castro Tiane Sena de, Buccheri Renata, Salomon Tassila, Dinardo Carla Luana, Moura Isabel Cristina Gomes, Crispim Myuki Alfaia Esashika, Fraiji Nelson Abrahim, Sabino Ester Cerdeira, Alencar Cecília Salete
Universidade de São Paulo, Faculdade de Medicina, São Paulo, São Paulo, Brazil.
Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil.
Rev Inst Med Trop Sao Paulo. 2025 May 26;67:e33. doi: 10.1590/S1678-9946202567033. eCollection 2025.
To assess SARS-CoV-2 reinfection incidence in the post-vaccination period, we carried out a prospective cohort study of blood donors from Amazonas and Sao Paulo States, Brazil. Anti-nucleocapsid immunoglobulin (IgG anti-N) tests carried out by blood centers in 2020 were used to identify previous SARS-CoV-2 infections in blood donors and divide them into two groups: prior infection (n=386) and no prior infection (n=111). From March 2021 to January 2022, donors were followed up for six months, during which IgG anti-N and real-time reverse transcription polymerase chain reaction tests were performed every two months to detect SARS-CoV-2 infections. Symptoms and vaccination status were also recorded. Most participants (93.6%) received at least one COVID-19 vaccine dose. Reinfection incidence in the prior infection group equaled 1.39 per 100 person-months (95% CI: 0.90-2.06), in comparison to 2.68 per 100 person-months (95% CI: 1.28-4.93) for new infections in those without prior infection. The incidence risk ratio showed no significant association (0.52, 95% CI: 0.25-1.13). However, prior infection significantly increased the probability of remaining uninfected (Log-rank: p=0.009). Most reinfections (84%) showed no symptoms and occurred post-vaccination during the Delta and Omicron waves. IgG anti-N seroprevalence decreased in the prior infection group (from 35.5% at baseline to 22.5% after six months, p=0.003). Despite no significant incidence risk ratio differences, donors with prior infection had lower infection rates and a higher likelihood of remaining uninfected. Persistent post-vaccination asymptomatic infections emphasize the need for ongoing prevention, genomic surveillance, and booster programs to address emerging variants and protect vulnerable populations.
为评估接种疫苗后时期严重急性呼吸综合征冠状病毒2（SARS-CoV-2）再次感染的发生率，我们对来自巴西亚马孙州和圣保罗州的献血者进行了一项前瞻性队列研究。利用血液中心在2020年进行的抗核衣壳免疫球蛋白（IgG抗N）检测来识别献血者既往的SARS-CoV-2感染情况，并将他们分为两组：既往感染组（n = 386）和无既往感染组（n = 111）。从2021年3月至2022年1月，对献血者进行了为期六个月的随访，在此期间每两个月进行一次IgG抗N检测和实时逆转录聚合酶链反应检测，以检测SARS-CoV-2感染情况。还记录了症状和疫苗接种状况。大多数参与者（93.6%）接种了至少一剂新冠疫苗。既往感染组的再次感染发生率为每100人月1.39例（95%置信区间：0.90 - 2.06），相比之下，无既往感染组新感染的发生率为每100人月2.68例（95%置信区间：1.28 - 4.93）。发病风险比未显示出显著关联（0.52，95%置信区间：0.25 - 1.13）。然而，既往感染显著增加了未感染的概率（对数秩检验：p = 0.009）。大多数再次感染（84%）没有症状，且发生在接种疫苗后德尔塔毒株和奥密克戎毒株流行期间。既往感染组的IgG抗N血清阳性率下降（从基线时的35.5%降至六个月后的22.5%，p = 0.003）。尽管发病风险比没有显著差异，但既往感染的献血者感染率较低且未感染的可能性较高。接种疫苗后持续存在的无症状感染凸显了持续开展预防、基因组监测以及加强针计划以应对新出现的变异毒株和保护弱势群体的必要性。
