If an individual was identified as a contact by a case and became a case or was already a case, we recorded these as a case-contact pair. 2022. As of July 26, 3,591 cases in 46 states, Puerto Rico, and Washington, D.C., have been diagnosed (see . The outbreak is small so far about 80 suspected cases in England, Spain and Canada as well. To estimate both the serial interval and the incubation period of monkeypox we used a large sample from the UK Health Security Agency (UKHSA) surveillance and contact tracing data. To help us improve GOV.UK, wed like to know more about your visit today. The paper was, however, read by members of the public upon submission. Individuals report other individuals who they have been in contact with or who they think might have infected them, but this does not necessarily mean transmission occurred during that contact. Therefore, backward contact tracing strategies should account for a pre-symptomatic infectious period when trying to find the contacts of confirmed cases. Since the international epidemic began in May, the U.S. has recorded 201. The outbreak has mainly been in gay, bisexual, and men who have sex with men without documented history of travel to endemic countries. As of Tuesday . The outbreak could spread beyond U.K. borders, the agency said, particularly because there appears . From the perspective of public health policy, this transmission before the detection of symptoms is equivalent to pre-symptomatic transmission, as it concerns when individuals might become aware of their infection. Other approaches can be applied to handle right truncation bias.21 We opted for our approach because the epidemic phase related terms, P(E=e*), cancel each other out, so we do not need to explicitly describe the phase of the epidemic within the model. Posterior distributions for mean and standard deviation of the serial interval for monkeypox. Monkeypox is a rare viral infection which does not spread easily . 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. Monkeypox is a misnomer that results from the fact that it was discovered at the Statens Serum Institut in Copenhagen in 1958, when outbreaks of a pox-like disease occurred in monkeys kept for. Monkeypox, a zoonotic disease, was identified in 1958 in monkeys showing signs of a poxvirus.1 The disease is caused by a virus belonging to the orthopoxvirus genus and was first detected in humans in 1970 in the Democratic Republic of the Congo.2 The disease has since become endemic in that region and spread to other central and west African countries. Table 3 shows the results of the cumulative distribution function of the incubation period distribution. Most confirmed cases with travel history reported travel to countries in Europe and North America, rather than West or Central Africa where the mpox virus is endemic. This sample size is small and relies on the completion of an optional case questionnaire and on the cases being linked by contact tracing. Goodrich B, Gabry J, Ali I, et al. These figures are used for official reporting of monkeypox confirmed case counts in the UK. 2022-2023 monkeypox outbreak 39 languages An ongoing outbreak of mpox, a viral disease, was confirmed in May 2022. These two sources of evidence provide greater confidence in the conclusions. The World Health Organization says the outbreak is primarily spreading through sex. Contributors: TW conceived and led the study. Although the outbreak was large, however, incidence was still low relative to the population size at risk. Participants 2746 people with polymerase chain . There has recently been an increase in cases in the UK, but the risk of catching it is low. **Address not yet confirmed. This publication is available at https://www.gov.uk/government/publications/monkeypox-outbreak-epidemiological-overview/monkeypox-outbreak-epidemiological-overview-4-october-2022. Dissemination to participants and related patient and public communities: We will disseminate the results to governmental organisations and agencies through official channels and publications. In other populations and with different disease severity, the incubation periods are likely to differ.29303132. To fit the model to the data, we used a Markov chain Monte Carlo (MCMC) implemented in Stan through the Cmdstanr package, with full model formula (equation 3, fig 1). If two records had the same pseudo identifier numbers for both individuals in the case-contact pair we assumed these to represent duplicates. For lognormal the model was parameterised in terms of the log mean, 1, and log standard deviation, 2, parameters. The outbreak is unusual because although the UK has had sporadic cases of monkeypox before - seven from 2018 to 2021 - all previous cases were linked to travel from Nigeria. Cumulative distribution function of the serial interval and incubation period for monkeypox. Our likelihood function therefore relies on three functions (equation 2, fig 1). Our finding does, however, provide evidence that there are patients who showed pre-symptomatic transmission in the monkeypox outbreak data. 10 out of 13 linked patients had documented pre-symptomatic transmission. In one study involving 18 infected participants, the estimated mean incubation period was 8.5 days (95% credible interval6.6 to 10.9).16 A limitation of this study was the small sample size, and therefore the findings were unlikely to be representative of the full distribution. Following the methods of Ward et al,22 this can be generalised to an epidemic that is not in an exponential phase, by replacing rt with a smooth function of time, s(t). Mpox (previously called monkeypox) is a viral zoonosis, and in humans, it shares several clinical characteristics with smallpox [1,2].Although smallpox has been eradicated worldwide since 1980, mpox is still endemic in parts of Central and Western Africa [3,4,5].However, it should be noted that most of the mpox cases recorded in the 2022 outbreak occurred in Western and European countries . [4] The time from exposure to onset of symptoms ranges from five to twenty-one days. UK Health Security Agency. UK Public Health Agencies. A rare case of monkeypox has been diagnosed in a patient in England, the UK Health Security Agency said in a statement Saturday. Using the cumulative distribution function of the serial interval distribution, the median number was 5.0 days (95% credible interval 3.8 to 6.2) for the ICC model and 5.8 days (4.3 to 7.6) for the ICRTC model (table 5). 2022. The Food and Drug Administration (FDA) is urging that providers be "judicious" in prescribing the Negative serial intervals are possible in the presence of pre-symptomatic transmission, although the nature of contact tracing data means that the direction of transmission can be difficult to infer from the data, and positive serial intervals are more likely than negative serial intervals. The monkeypox epidemic in the UK has been largely based in dense social networks with high contact rates.24 Particularly, transmission has been largely clustered around a subset of gay, bisexual, and other men who have sex with men who engage in behaviours that put them at higher risk of infection and transmission. Vaccinating less than half of high-risk men may stop monkeypox spread,A modelling study suggests that between 5 and 47 per cent of high-risk men who have sex with men would need to be vaccinated to stop the ongoing monkeypox outbreak technical support for your product directly (links go to external sites): Thank you for your interest in spreading the word about The BMJ. At the end of the study period, 1 August, case numbers were halving every 29 days (38.02 to 23.44). Adjustments for interval censoring, right truncation, and epidemic phase bias are essential for data that are coarsely collected28 and linked to probable, not deterministic, exposure events. 2020 Election Business Tech . However, anyone, regardless of sexual orientation or gender identity, who has been in close, personal contact with someone who has mpox is at risk. This is combined with case information recorded by local Health Protection Teams in the UKHSA national case management system. Cases of monkeypox infection were confirmed in England from 6 May 2022. Supplementary material B shows the results of the Weibull and lognormal models. To estimate this smooth function, we fit a generalised additive model to daily confirmed case counts with a negative binomial error structure and log link. Data on monkeypox in children and adolescents aged <18 years are limited (1,2). Red arrow indicates number of days between primary onset and secondary onset (serial interval). We refer to this model as the double interval censoring corrected model (ICC). This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. For the serial interval, this is the time between the symptom onset date in the primary case (primary event) and the symptom onset date in the secondary contact (secondary event). The endemic regions were identified in Africa's central and western areas. [36], Confirmed cases by countries in the United Kingdom during the 2022 outbreak (as of 12 July), The first three paragraphs an excerpt from, 20222023 monkeypox outbreak in the United Kingdom, Number of cases confirmed in constituent countries. England counts may differ from those published in the Notifications of infectious diseases (NOIDs) causative agents weekly report. Although case numbers are declining, increased international transmission would facilitate infection importation and might drive stochastic outbreaks even if vaccination in local networks limits transmission. Monkeypox was first detected in 1970 in the Democratic Republic of the Congo, The incubation period and serial interval have been estimated from observational studies, Since the international outbreak of monkeypox in May 2022 a study estimated a mean incubation period of 8.5 days; however, the sample size was small (n=18), This study found evidence of pre-symptomatic transmission of monkeypox, using contact tracing data and adjustments for interval censoring, right truncation, and epidemic phase bias, The maximum time that transmission was detected before symptoms manifested for infected individuals who could be linked through reliable personal identifiable information was four days. [4][14] People can spread the virus from the onset of symptoms until all the lesions have scabbed and fallen off; with some evidence of spread for more than a week after lesions have crusted. Of the 30 primary cases, 19 had a symptom onset date recorded in the line list. For example, more than half of respondents to case questionnaires in the UK had a history of a sexually transmitted infection over the past year, and 31% had at least 10 or more sexual partners in the past three months.25 In the UK outbreak, the median age of infected individuals was 37 years,25 in contrast with earlier outbreaks in the Democratic Republic of the Congo where in 2016 the median age was 10 years and by 2020 only 42% of cases were older than 5 years.1426 This is indicative of changes in the primary routes of transmission for the monkeypox virus in the 2022 epidemic. 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. From the MCMC output, we obtained a posterior distribution of parameters, which describes the distribution of parameters considered by the model. Recently, sporadic MPXV infections in several nonendemic countries have attracted widespread attention. Funding: The authors were employed by the UK Health Security Agency but received no specific funding for this study. Data are obtained from three types of questionnaires: A questionnaire administered by health practitioners, An anonymous self-completed questionnaire, All questionnaires are optional, and individuals are not required to complete all questions. Additionally, the conclusions around the presence of pre-symptomatic transmission are supported by analysis of the relative shapes of both the incubation period and the serial interval distributions as well as individual level patient data. Copyright 2023 BMJ Publishing Group Ltd, A systematic review of the epidemiology of human monkeypox outbreaks and implications for outbreak strategy, Comparison of West African and Congo Basin monkeypox viruses in BALB/c and C57BL/6 mice, Virulence differences between monkeypox virus isolates from West Africa and the Congo basin, On the relationship between serial interval, infectiousness profile and generation time, Presymptomatic transmission of SARS-CoV-2 infection: a secondary analysis using published data, Serial interval of novel coronavirus (COVID-19) infections, Human monkeypox: disease pattern, incidence and attack rates in a rural area of northern Zaire, Extended Human-to-Human Transmission during a Monkeypox Outbreak in the Democratic Republic of the Congo, Estimated incubation period for monkeypox cases confirmed in the Netherlands, May 2022, Understanding an evolving pandemic: An analysis of the clinical time delay distributions of COVID-19 in the United Kingdom, Hospital length of stay for COVID-19 patients: Data-driven methods for forward planning, Inference from Iterative Simulation Using Multiple Sequences, Estimating a time-to-event distribution from right-truncated data in an epidemic: A review of methods, Growth, reproduction numbers and factors affecting the spread of SARS-CoV-2 novel variants of concern in the UK from October 2020 to July 2021: a modelling analysis, Estimating incubation period distributions with coarse data, Shorter incubation period is associated with severe disease progression in patients with COVID-19, Brief Report: Incubation Period Duration and Severity of Clinical Disease Following Severe Acute Respiratory Syndrome Coronavirus Infection, Association between Severity of MERS-CoV Infection and Incubation Period, Incubation period, severity of disease, and infecting dose: evidence from a Salmonella outbreak, Surveillance, case investigation and contact tracing for monkeypox: interim guidance, 25 August 2022, Transmission dynamics of monkeypox in the United Kingdom: contact tracing study, https://www.gov.uk/government/publications/accessing-ukhsa-protected-data/accessing-ukhsa-protected-data, https://github.com/OvertonC/Transmission-Dynamics-of-Monkeypox-in-the-United-Kingdom, http://creativecommons.org/licenses/by-nc/4.0/, https://www.who.int/news-room/fact-sheets/detail/monkeypox, https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON385, https://www.gov.uk/government/publications/monkeypox-outbreak-epidemiological-overview/monkeypox-outbreak-epidemiological-overview-13-september-2022, https://www.who.int/europe/news/item/23-07-2022-who-director-general-declares-the-ongoing-monkeypox-outbreak-a-public-health-event-of-international-concern, https://www.gov.uk/government/publications/principles-for-monkeypox-control-in-the-uk-4-nations-consensus-statement/principles-for-monkeypox-control-in-the-uk-4-nations-consensus-statement#:~:text=In%20the%20UK%2C%20all%20reported,about%20the%20West%20Afr, https://mc-stan.org/rstanarm/reference/loo.stanreg.html, https://www.ecdc.europa.eu/sites/default/files/documents/Considerations-for-Contact-Tracing-MPX_June%202022.pdf, https://www.gov.uk/government/publications/monkeypox-outbreak-technical-briefings/investigation-into-monkeypox-outbreak-in-england-technical-briefing-1#part-2-epidemiology-update, https://www.gov.uk/government/publications/monkeypox-outbreak-technical-briefings/investigation-into-monkeypox-outbreak-in-england-technical-briefing-3, https://web.archive.org/web/20220605103903/https://www.who.int/emergencies/disease-outbreak-news/item/monkeypox-democratic-republic-of-the-congo, https://www.gov.uk/government/publications/monkeypox-outbreak-technical-briefings/investigation-into-monkeypox-outbreak-in-england-technical-briefing-1#part-3-genomics, https://www.who.int/publications/i/item/WHO-MPX-Surveillance-2022.3, Birmingham and Solihull Mental Health NHS Foundation Trust: Consultant Psychiatrist General Adult - Northcroft CMHT, Brent Area Medical Centre: Salaried GP - Brent Area Medical Centre, Onebright Ltd: Consultant Psychiatrist (Neurodiversity) - Remote / London, The Royal Hospital for Neurodisability: Clinical Fellow, Womens, childrens & adolescents health. 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