Statistics, Modelling and Economics, Data, Analytics and Surveillance, UK Health Security Agency, London, UK.
Immunisation and Vaccine Preventable Diseases Division, UK Health Security Agency, London, UK; Blood Safety, Hepatitis, Sexually Transmitted Infections and HIV Division, UK Health Security Agency, London, UK.
Lancet Infect Dis. 2024 Jan;24(1):65-74. doi: 10.1016/S1473-3099(23)00451-6. Epub 2023 Sep 11.
The 2022 global outbreak of mpox (formerly known as monkeypox) spread primarily among gay, bisexual, and other men who have sex with men (GBMSM), with the initial cluster being identified in England in May, 2022. Understanding its epidemiological characteristics and the reasons for its downturn in July, 2022, will help to control future outbreaks.
We collated data for all diagnosed mpox cases (3621) from England from May 1, 2022, to Nov 16, 2022. Data from 75 individuals with mpox allowed estimation of the incubation period, while data from 121 case-contact pairs were used to estimate the serial interval. Six methods, including a structured dynamic compartmental transmission model, were used to estimate the basic reproduction number (R). The structured model assumed all male individuals with mpox were GBMSM, who were then stratified into subgroups for those at low risk and high risk for mpox. This best fitting model was used to estimate the reduction in transmissibility, and the effective infectious period (before isolating), that resulted in the outbreak downturn, and the effect of vaccination initiated from June 27, 2022. Bayesian methods were used for parameter estimation and model calibration.
Most cases occurred in men (3544 of 3621, 97·9%). The median incubation period for mpox was 6·90 days (95% credible interval [CrI] 4·08-20·21), and the serial interval was 8·82 days (5·22-25·81). R estimates ranged from 1·41 to 2·17. The structured transmission model estimated that 83·8% of infections (95% CrI 83·5-85·3) resulted from sexual partnerships with GBMSM individuals at high risk of mpox. The outbreak downturn probably resulted from a 44·5% reduction in the sexual partner rate among all GBMSM (24·9-55·8) and 20·0% reduction in the effective infectious period (4·1-33·9), preventing 165 896 infections (115 584-217 730). Vaccination marginally increased the number of infections prevented (166 081, 115 745-217 947), but minimised a resurgence in cases from January, 2023, and could have averted four times more infections if initiated earlier. Our findings were sensitive to assumptions regarding the vaccine's effectiveness and the GBMSM subgroup at high risk of mpox.
The mpox outbreak in England probably resulted from high sexual partner rates among some GBMSM, with reductions in partner rates reversing the outbreak, and with vaccination minimising future outbreaks.
National Institute for Health Research (UK).
2022 年全球猴痘（以前称为猴痘）爆发主要发生在男同性恋者、双性恋者和其他与男性发生性关系的男性（GBMSM）中，最初的聚集病例于 2022 年 5 月在英国发现。了解其流行病学特征和 2022 年 7 月下降的原因，将有助于控制未来的爆发。
我们从 2022 年 5 月 1 日至 11 月 16 日期间整理了英国所有确诊的猴痘病例（3621 例）的数据。75 名猴痘患者的数据用于估计潜伏期，而 121 对病例接触者的数据用于估计序列间隔。包括一个结构化动态房室传输模型在内的六种方法用于估计基本繁殖数（R）。该结构化模型假设所有患有猴痘的男性都是 GBMSM，然后将他们分为低风险和高风险亚组。使用最佳拟合模型来估计传播率降低以及导致疫情下降的有效感染期（隔离前），以及从 2022 年 6 月 27 日开始接种疫苗的效果。贝叶斯方法用于参数估计和模型校准。
大多数病例发生在男性（3544 例，占 3621 例的 97.9%）。猴痘的中位潜伏期为 6.90 天（95%可信区间[CrI] 4.08-20.21），序列间隔为 8.82 天（5.22-25.81）。R 估计值范围为 1.41 至 2.17。结构传播模型估计，83.8%的感染（95% CrI 83.5-85.3）是由与高风险猴痘的 GBMSM 个体的性伴侣关系引起的。疫情下降可能是由于所有 GBMSM 的性伴侣率降低了 44.5%（24.9-55.8），有效感染期缩短了 20.0%（4.1-33.9），从而预防了 165896 例感染（115584-217730）。疫苗接种略微增加了预防的感染数量（166081 例，115745-217947），但从 2023 年 1 月开始，病例的再次出现减少，并可将感染人数减少四倍，如果更早开始接种疫苗。我们的研究结果对疫苗有效性和高风险猴痘的 GBMSM 亚组的假设敏感。
英国的猴痘疫情可能是由于一些 GBMSM 的性伴侣率较高所致，降低性伴侣率可扭转疫情，而疫苗接种可最大程度地减少未来的疫情爆发。
英国国家卫生研究院（UK）。
