英国卫生安全局Thomas Ward团队通过接触者追踪研究分析了猴痘在英国的传播动态。该项研究成果发表在2022年11月2日出版的《英国医学杂志》上。

为了分析2022年7月被宣布为国际关注突发公共卫生事件的英国猴痘疫情的传播动态，研究组通过英国卫生安全局（UKHSA）的病例调查问卷，进行接触追踪研究，并病例接触对和可能接触日期的数据进行关联。

2022年5月6日至8月1日，英国有2746人通过聚合酶链反应确诊猴痘病毒。使用两个贝叶斯时间延迟模型对猴痘感染的潜伏期和序列间隔进行了校正，一个校正了区间间隔，另一个校正区间间隔、右截尾和流行期偏差。使用广义加权模型估计了猴痘病毒确诊并报告给UKHSA的报告日期的病例增长率。

参与者的平均年龄为37.8岁，95%的人报告为同性恋、双性恋或其他与男性发生性行为的男性（1213人中有1160人报告）。使用ICC模型估计平均潜伏期为7.6天，使用ICRTC模型估计为7.8天。使用ICC模型估计的平均序列间隔为8.0天，使用ICRTC模型估计为9.5天。

尽管两种模型的平均序列间隔比潜伏期长，但短序列间隔比短潜伏期更常见，序列间隔的第25个百分位数和中位数比潜伏期短。对于ICC和ICRTC模型，相应的估计值在第25个百分位数时分别缩短1.8天与1.6天，中位数分别缩短1.6天与0.8天。13名关联患者中有10名有症状前传播记录。病例倍增时间从5月6日英国报告首例猴痘病例时的9.07天下降至8月1日的29天。

综上，对猴痘发病率瞬时增长率的分析表明，截至7月9日，该流行病在英国达到顶峰，然后开始下降。短连续间隔比短潜伏期更常见，这表明有相当大的症状前传播，这通过相关的患者水平记录得到验证。

对于可通过个人身份数据联系起来的患者，4天是在症状出现之前检测到传播的最长时间。要检测95%的潜在感染者，需要16至23天的隔离期。连续间隔的第95个百分位数在23到41天之间，表明感染期较长。

附：英文原文

Title: Transmission dynamics of monkeypox in the United Kingdom: contact tracing study

Author: Thomas Ward, Rachel Christie, Robert S Paton, Fergus Cumming, Christopher E Overton

Issue&Volume: 2022/11/02

Abstract:

Objective To analyse the transmission dynamics of the monkeypox outbreak in the UK, declared a Public Health Emergency of International Concern in July 2022.

Design Contact tracing study, linking data on case-contact pairs and on probable exposure dates.

Setting Case questionnaires from the UK Health Security Agency (UKHSA), United Kingdom.

Participants 2746 people with polymerase chain reaction confirmed monkeypox virus in the UK between 6 May and 1 August 2022.

Main outcome measures The incubation period and serial interval of a monkeypox infection using two bayesian time delay models—one corrected for interval censoring (ICC—interval censoring corrected) and one corrected for interval censoring, right truncation, and epidemic phase bias (ICRTC—interval censoring right truncation corrected). Growth rates of cases by reporting date, when monkeypox virus was confirmed and reported to UKHSA, were estimated using generalised additive models.

Results The mean age of participants was 37.8 years and 95% reported being gay, bisexual, and other men who have sex with men (1160 out of 1213 reporting). The mean incubation period was estimated to be 7.6 days (95% credible interval 6.5 to 9.9) using the ICC model and 7.8 days (6.6 to 9.2) using the ICRTC model. The estimated mean serial interval was 8.0 days (95% credible interval 6.5 to 9.8) using the ICC model and 9.5 days (7.4 to 12.3) using the ICRTC model. Although the mean serial interval was longer than the incubation period for both models, short serial intervals were more common than short incubation periods, with the 25th centile and the median of the serial interval shorter than the incubation period. For the ICC and ICRTC models, the corresponding estimates ranged from 1.8 days (95% credible interval 1.5 to 1.8) to 1.6 days (1.4 to 1.6) shorter at the 25th centile and 1.6 days (1.5 to 1.7) to 0.8 days (0.3 to 1.2) shorter at the median. 10 out of 13 linked patients had documented pre-symptomatic transmission. Doubling times of cases declined from 9.07 days (95% confidence interval 12.63 to 7.08) on the 6 May, when the first case of monkeypox was reported in the UK, to a halving time of 29 days (95% confidence interval 38.02 to 23.44) on 1 August.

Conclusions Analysis of the instantaneous growth rate of monkeypox incidence indicates that the epidemic peaked in the UK as of 9 July and then started to decline. Short serial intervals were more common than short incubation periods suggesting considerable pre-symptomatic transmission, which was validated through linked patient level records. For patients who could be linked through personally identifiable data, four days was the maximum time that transmission was detected before symptoms manifested. An isolation period of 16 to 23 days would be required to detect 95% of people with a potential infection. The 95th centile of the serial interval was between 23 and 41 days, suggesting long infectious periods.

DOI: 10.1136/bmj-2022-073153

Source: https://www.bmj.com/content/379/bmj-2022-073153