Centre for Infectious Disease Control, National Institute of Public Health and the Environment, Bilthoven, The Netherlands.
Center for Marine Environmental Studies, Ehime University, Ehime, Japan.
J Infect Dis. 2024 Jul 25;230(1):e121-e130. doi: 10.1093/infdis/jiad414.
In the Netherlands, the number of mpox cases started declining before mpox vaccination was initiated. Most cases were men who have sex with men (MSM). We investigated whether the decline in mpox could be attributed to infection-induced immunity or behavioral adaptations.
We developed a transmission model and accounted for possible behavioral adaptations: fewer casual partners and shorter time until MSM with mpox refrain from sexual contacts.
Without behavioral adaptations, the peak in modelled cases matched observations, but the decline was less steep than observed. With behavioral adaptations in the model, we found a decline of 16%-18% in numbers of casual partners in June and 13%-22% in July 2022. Model results showed a halving of the time before refraining from sex. When mpox vaccination started, 57% of MSM with very high sexual activity in the model had been infected. Model scenarios revealed that the outbreak could have waned by November 2022 even without vaccination.
The limited duration of the mpox outbreak in the Netherlands can be ascribed primarily to infection-induced immunity among MSM with high sexual activity levels. The decline was accelerated by behavioral adaptations. Immunity among those most sexually active is essential to impede mpox resurgence.
在荷兰，在启动猴痘疫苗接种之前，猴痘病例数开始下降。大多数病例是男男性行为者（MSM）。我们调查了猴痘的下降是否归因于感染诱导的免疫或行为适应性。
我们开发了一个传播模型，并考虑了可能的行为适应性：MSM 中患有猴痘的人与性伴侣接触的时间更短，性伴侣也更少。
如果没有行为适应性，模型中病例的峰值与观察结果相符，但下降幅度小于观察结果。在模型中存在行为适应性的情况下，我们发现 2022 年 6 月和 7 月，偶然伴侣的数量分别减少了 16%-18%，7 月和 8 月的性接触时间分别减少了 13%-22%。模型结果表明，MSM 避免性接触的时间缩短了一半。当猴痘疫苗接种开始时，模型中非常活跃的 57%的 MSM 已经感染了猴痘。模型情景表明，即使没有疫苗接种，疫情也可能在 2022 年 11 月前消退。
荷兰猴痘疫情的持续时间有限，主要归因于性活动水平较高的 MSM 中的感染诱导免疫。行为适应性加速了下降。最活跃人群的免疫力对于阻止猴痘疫情的再次爆发至关重要。
