Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil; Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil; Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, United States.
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, United States; Department of Laboratory Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Int J Infect Dis. 2024 Feb;139:159-167. doi: 10.1016/j.ijid.2023.11.039. Epub 2023 Dec 7.
The SARS-CoV-2 BQ.1* variant rapidly spread globally in late 2022, posing a challenge due to its increased immune evasion.
We conducted a prevalence survey in Brazil from November 16 to December 22, 2022, as part of a cohort study. We conducted interviews and collected nasal samples for reverse transcription-polymerase chain reaction (RT-PCR) testing and whole-genome sequencing. Cumulative incidence was estimated using RT-PCR positivity, cycle threshold values, and external data on the dynamics of RT-PCR positivity following infection.
Among 535 participants, 54% had documented SARS-CoV-2 exposure before this outbreak and 74% had received COVID-19 vaccination. In this study, 14.8% tested positive for SARS-CoV-2, with BQ.1* identified in 90.7% of cases. Using case data and cycle threshold values, cumulative incidence was estimated at 56% (95% confidence interval, 36-88%). Of the 79 positive participants, 48.1% had a symptomatic illness, with a lower proportion fulfilling the World Health Organization COVID-19 case definition compared to prior Omicron waves. No participants required medical attention.
Despite high population-level hybrid immunity, the BQ.1* variant attacked 56% of our population. Lower disease severity was associated with BQ.1* compared to prior Omicron variants. Hybrid immunity may provide protection against future SARS-CoV-2 variants but in this case was not able to prevent widespread transmission.
2022 年末，SARS-CoV-2 BQ.1*变异株迅速在全球范围内传播，因其免疫逃逸能力增强而构成挑战。
我们于 2022 年 11 月 16 日至 12 月 22 日在巴西进行了一项患病率调查，作为一项队列研究的一部分。我们进行了访谈并采集了鼻拭子样本，用于逆转录-聚合酶链反应（RT-PCR）检测和全基因组测序。使用 RT-PCR 阳性率、循环阈值（Ct）值以及感染后 RT-PCR 阳性率的外部数据来估计累积发病率。
在 535 名参与者中，54%在此次暴发前有记录的 SARS-CoV-2 暴露史，74%已接种 COVID-19 疫苗。在本研究中，14.8%的人 SARS-CoV-2 检测呈阳性，其中 90.7%的病例为 BQ.1*。使用病例数据和 Ct 值，估计累积发病率为 56%（95%置信区间，36%-88%）。在 79 名阳性参与者中，48.1%有症状疾病，与之前的奥密克戎波相比，符合世界卫生组织 COVID-19 病例定义的比例较低。没有参与者需要医疗关注。
尽管人群混合免疫力水平较高，但 BQ.1变异株攻击了我们 56%的人群。与之前的奥密克戎变体相比，BQ.1与较低的疾病严重程度相关。混合免疫力可能为未来的 SARS-CoV-2 变体提供保护，但在这种情况下，它无法阻止广泛传播。
