Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, Québec, Canada.
Direction Régionale de Santé Publique de Montréal, Montréal, Québec, Canada.
J Int AIDS Soc. 2022 Sep;25(9):e25994. doi: 10.1002/jia2.25994.
Men who have sex with men (MSM) and people who inject drugs (PWID) are disproportionately impacted by the HIV epidemic in Canada. Having the second-highest provincial diagnosis rate, an improved understanding of the epidemic among these populations in Québec could aid ongoing elimination efforts. We estimated HIV incidence and other epidemic indicators among MSM and PWID in Montréal and across Québec using a back-calculation model synthesizing surveillance data.
We developed a deterministic, compartmental mathematical model stratified by age, HIV status and disease progression, and clinical care stages. Using AIDS and HIV diagnoses data, including self-reported time since the last negative test and laboratory results of CD4 cell count at diagnosis, we estimated HIV incidence in each population over 1975-2020 by modelling a cubic M-spline. The prevalence, undiagnosed fraction, fraction diagnosed that started antiretroviral treatment (ART) and median time to diagnosis were also estimated. Since the COVID-19 pandemic disrupted testing, we excluded 2020 data and explored this in sensitivity analyses.
HIV incidence in all populations peaked early in the epidemic. In 2020, an estimated 97 (95% CrI: 33-227) and 266 (95% CrI: 103-508) HIV acquisitions occurred among MSM in Montréal and Québec, respectively. Among PWID, we estimated 2 (95% CrI: 0-14) and 6 (95% CrI: 1-26) HIV acquisitions in those same regions. With 2020 data, unless testing rates were reduced by 50%, these estimates decreased, except among Québec PWID, whose increased. Among all, the median time to diagnosis shortened to <2 years before 2020 and the undiagnosed fraction decreased to <10%. This fraction was higher in younger MSM, with 22% of 15-24 year-olds living with HIV in Montréal (95% CrI: 9-39%) and 31% in Québec (95% CrI: 17-48%) undiagnosed by 2020 year-end. Finally, ART access neared 100% in all diagnosed populations.
HIV incidence has drastically decreased in MSM and PWID across Québec, alongside significant improvements in diagnosis and treatment coverage-and the 2013 introduction of pre-exposure prophylaxis. Despite this, HIV transmission continued. Effective efforts to halt this transmission and rapidly diagnose people who acquired HIV, especially among younger MSM, are needed to achieve elimination. Further, as the impacts of the COVID-19 pandemic on HIV transmission are understood, increased efforts may be needed to overcome these.
男男性行为者（MSM）和注射毒品者（PWID）在加拿大的 HIV 流行中受到不成比例的影响。魁北克省的 HIV 发病率在省级中排名第二，因此深入了解这些人群中的流行情况可能有助于正在进行的消除努力。我们使用综合监测数据的回溯模型，估计了蒙特利尔和魁北克省所有 MSM 和 PWID 中的 HIV 发病率和其他流行指标。
我们开发了一种确定性、分层的数学模型，按年龄、HIV 状态和疾病进展以及临床护理阶段进行分层。使用 AIDS 和 HIV 诊断数据，包括最后一次阴性检测后的时间报告和 CD4 细胞计数诊断时的实验室结果，我们通过对三次 M 样条进行建模，估计了每个群体在 1975 年至 2020 年期间的 HIV 发病率。还估计了流行率、未诊断部分、开始接受抗逆转录病毒治疗（ART）的诊断部分和中位诊断时间。由于 COVID-19 大流行扰乱了检测，我们排除了 2020 年的数据，并在敏感性分析中对此进行了探讨。
所有人群的 HIV 发病率在疫情早期达到峰值。2020 年，估计蒙特利尔和魁北克省 MSM 中分别有 97 例（95%置信区间：33-227）和 266 例（95%置信区间：103-508）HIV 获得性感染。在 PWID 中，我们估计在同一地区，这两个地区分别有 2 例（95%置信区间：0-14）和 6 例（95%置信区间：1-26）HIV 获得性感染。有了 2020 年的数据，除非检测率降低 50%，否则这些估计值会下降，除了魁北克省的 PWID 除外，其估计值有所增加。在所有人群中，到 2020 年之前，诊断中位时间缩短至<2 年，未诊断部分降至<10%。在较年轻的 MSM 中，这一比例更高，其中 15-24 岁的 MSM 中有 22%（95%置信区间：9-39%）在蒙特利尔和 31%（95%置信区间：17-48%）在魁北克省未被诊断出到 2020 年年末。最后，所有诊断人群的 ART 覆盖率均接近 100%。
魁北克省所有 MSM 和 PWID 的 HIV 发病率均大幅下降，同时诊断和治疗覆盖率也显著提高——自 2013 年以来，暴露前预防的引入也起到了作用。尽管如此，HIV 仍在传播。需要采取有效的措施来阻止这种传播，并迅速诊断出感染 HIV 的人，尤其是年轻的 MSM，以实现消除目标。此外，随着对 COVID-19 大流行对 HIV 传播影响的了解，可能需要加大努力来克服这些影响。
