The 2022 mpox outbreak led to a rapid case surge among men who have sex with men (MSM) in previously unaffected regions, followed by a sudden decline, whose drivers remain unclear. We developed a network model of mpox transmission among MSM based on sexual behaviour data, focusing on the Paris region epidemic. Our analysis tested three drivers for the decline: postexposure prophylaxis vaccination, immunity among highly active MSM and behavioural adaptations, either uniform in the population or based on individual risk factors. Behavioural changes adopted by 49

Background The 2024 Paris Summer Olympics and Paralympics Games (OPG) were held predominantly in Paris and the seven surrounding Départements of Île-de-France (IdF) Région, from 26/07 to 08/09. To contextualize epidemiological findings, we estimated population denominators, accounting for vacationers’ departures and visitors’ arrivals. Methods We used daily population estimates produced by a specialized mobile phone company, modelled using antennae-mobile phone connection data (MPD). These were available for the period 01/06-30/09 and for each IdF Département, detailing the provenance in France or 180 other countries or territories of the SIM card registration, regardless of the telephone operator. Results A total of 493,368,201 person-days were documented in IdF during the 45-day OPG surveillance period. Of these, 63.9% were attributed to IdF residents of any nationality, 12.8% to French non-IdF residents, 8.2% to non-French EU/UK/Swiss and 15.1% to non-EU/UK/Swiss residents. Over the entire Summer, the estimated daily IdF resident population in IdF went from a maximum of 10,636,392 on 04/06 to a minimum of 5,709,363 on 17/08 (-46.3% of baseline). Visitors from outside EU/UK/Swiss of any nationality went from a maximum of 1,834,441 on 02/08 to a minimum of 1,467,726 on 01/09. MPD-based population estimates were used to contextualize the end-of-summer rise in indicators and estimate the number of visitors from epidemic countries when influenza A virus was detected or Mpox was declared an international emergency in August, 2024. Conclusion Near-real-time, MPD-based population estimates were used as denominators to effectively and usefully interpret epidemiological indicators in the 2024 summer and OPG period during which the IdF population was highly diverse and mobile. This approach is a legacy of the 2024 OPG and should be instituted routinely.

BACKGROUND:The abridged Institut Pasteur du Cambodge (IPC) 3-session intradermal (ID) rabies post-exposure prophylaxis (PEP) regimen has been shown to be as safe and immunogenic as the 4-session regimen previously recommended by WHO. This regimen reduces time, cost, improves adherence and access to PEP for underserved people. Our study aimed to compare long-term and anamnestic immune response after a rabies vaccine booster dose in people previously vaccinated with a 3 or 4-session ID PEP. METHODS:In this prospective, multi-site, comparative immunogenicity study, we measured rabies virus neutralizing antibody in 181 persons that had previously received 3- or 4-session ID PEP, 2, 5, or 10 years earlier in Cambodia or Madagascar, at day 0 and at day 7 after a booster. In addition, RABV-specific T cell response was evaluated in a sub-group of 35 Cambodian participants. RESULTS:All participants had rabies virus neutralizing antibody titers considered adequate (≥ 0.5 IU/mL) on day 7 after the booster dose. The overall geometric mean titer (GMT) of rabies antibody on day 0 and day 7 did not differ significantly between the 2 groups. Furthermore, RABV-specific T cell response was similar regardless of the ID PEP regimen initially received in a sub-group of 35 participants. CONCLUSIONS:In this multisite, real-world study, we showed that the 3-session ID PEP regimen provides robust long-term immunogenicity up to 10 years after initial PEP and ensures the induction of an adequate anamnestic response within 7 days after an additional booster in all participants.

Abstract Background Despite the decline of the 2022 global outbreak, mpox remains an ongoing public health concern, with persistent transmission and emerging viral clades sustaining resurgence risk. Improving preparedness and response is a priority, yet it remains unclear how best pre-exposure vaccination and community response can effectively limit transmission under realistic conditions and whether behavioral adaptation is critical. Methods We used a data-driven network model of mpox transmission among men who have sex with men in the Paris region, parameterized with sexual behavioral data and calibrated to surveillance data from the 2022 outbreak. We evaluated counterfactual scenarios by varying vaccination timing, rollout speed, prioritization, and behavioral responses. Results Here we show that, with respect to the 2022 epidemic in the Paris region, vaccination alone delivered at the observed rollout speed would not have reproduced the observed epidemic decline, even if initiated the day of the first European alert, corresponding to 12 days before the first case was reported in France. Achieving comparable control through vaccination alone would have required more than a fourfold increase in rollout speed. Large-scale and long-term reductions in sexual contacts remain instrumental to limit the epidemic size, although earlier vaccination reduces the proportion of MSM needing to change behavior. In contrast, short-term behavioral measures adopted by the vaccinees, such as sexual abstinence during the 14-day immunity-building period, combined with moderately faster vaccine rollout, (+68% for 50% compliance; +34% for 75% compliance) could achieve comparable epidemic control. Targeting individuals with higher sexual activity further improved intervention efficiency. Conclusions Under realistic reactive vaccination scenarios, mpox control still requires strong behavioral responses. Combining timely vaccination with short-term behavioral change guidance at vaccine administration offers a feasible path to limit transmission and strengthen outbreak preparedness and response.

In June 2026, an intensive care physician deployed in the Democratic Republic of the Congo and previously vaccinated against Ebola virus developed fatigue, nausea and headaches while returning to France. Bundibugyo virus was identified with RT-PCR. The patient was treated with remdesivir and recovered fully. Contact tracing identified five low-risk contacts and no secondary cases. Stringent infection prevention and control measures and multidisciplinary collaboration are important when managing suspected or confirmed Ebola disease cases, even with low viral loads.

Chikungunya virus (CHIKV) is known to circulate in Africa, but there is little evidence of CHIKV transmission in Côte d’Ivoire. Using genomic data, we linked CHIKV cases imported in France from Côte d’Ivoire to a lineage from the West African genotype, likely been circulating in the country since July 2021.

In July 2024, a 47-year-old male presented with a laboratory-confirmed chikungunya infection in Paris, Île-de-France. Although he had travelled to Côte d'Ivoire for 2 days, symptoms appeared 27 days after his return. This autochthonous case represents the first and northernmost reported autochthonous case of chikungunya in France since 2017.

Yearly bronchiolitis and influenza-like illness epidemics in France often involve high morbidity and mortality, which severely impact health care. Epidemics are declared by the French National Institute of Public Health based on syndromic surveillance of primary care and emergency departments (EDs), using statistics-based alarms. Although the effective reproduction number (Rt) is used to monitor the dynamics of epidemics, it has never been used as an early-warning tool for bronchiolitis or influenza-like illness epidemics in France. We assessed whether Rt is useful for detecting seasonal epidemics by comparing it to the tool currently used (MASS) by epidemiologists to declare epidemic phases. We used anonymized ED syndromic data from the Île-de-France region in France from 2010 to 2022. We estimated Rt and compared the indication of accelerated transmission (Rt > 1) to the MASS epidemic alarm time points. We computed the difference between those 2 time points, time to epidemic peak, and the daily cases documented at first indication and peak. Rt provided alarms for influenza-like illness and bronchiolitis epidemics that were, respectively, a median of 6 days (IQR, 4, 8) and 64 days (IQR, 52, 80) earlier than the alarms provided by MASS. Rt detected earlier signals of bronchiolitis and influenza-like illness epidemics. Using this early-warning indicator in combination with others to declare an annual epidemic could provide opportunities to improve health care system readiness.

The 2022 mpox outbreak saw a rapid case surge among men-who-have-sex-with-men (MSM) in previously unaffected regions, driven by heterogeneity in sexual networks. A sudden decline followed, but its drivers remain unclear as it is difficult to distinguish the roles of vaccination, herd immunity, and behavioral changes. We developed a network model of mpox transmission among MSM based on sexual behavior data and fitted it to the Paris region epidemic. We studied whether the decline was driven by post-exposure prophylaxis (PEP) vaccination, immunity among highly active MSM, or behavioral changes. Behavioral shifts were modeled as either uniform or based on individual risk factors, like sexual activity or exposure to diagnosed cases. We used the cross-sectional 2023 ERAS survey to validate findings. Behavioral changes adopted by 49% (95%CI 47-51%) of MSM regardless of individual risk factors best explained the observed epidemic decline. These changes prevented an estimated 73% (28-99%) of mpox cases in summer 2022. Findings aligned with the ERAS survey data, showing that 46% (45-48%) of MSM reduced sexual partners. On the contrary, PEP vaccination and immunity among highly active MSM were insufficient to curb the outbreak. Widespread behavioral change was the primary driver of the mpox epidemic decline in the Paris region, before preventive vaccination or immunity could affect epidemic spread. These findings highlight the importance of effective risk communication and community engagement in outbreak management. Tailored public health responses that encourage adaptive behaviors, especially as vaccination efforts ramp up, are essential for supporting affected communities. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was partially funded by: ANRS-MIE grant MPX-SPREAD (ANRS0292); ANR grant DATAREDUX (ANR-19-CE46-0008-03); EU Horizon 2020 grant MOOD (H2020-874850); EU Horizon Europe grants VERDI (101045989) and ESCAPE (101095619). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All surveillance data were anonymised before use. Surveillance was considered as non interventional research only requiring the non opposition of the patient (article L1211 of the French public health code). The Comite de protection des personnes Ile de France IX (n 2014 A01605 42) authorized the PREVAGAY study. Inserm's Ethics Evaluation Committee (IRB00003888 avis n 23 989) approved the ERAS study. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data from PREVAGAY and ERAS studies can be made available to researchers upon request to Annie Velter, subject to approval of the proposed analyses and agreement to adhere to security, confidentiality, and collaborative conditions.

BackgroundWastewater surveillance is an effective approach to monitor population health, as exemplified by its role throughout the COVID-19 pandemic.AimThis study explores the possibility of extending wastewater surveillance to the Paris 2024 Olympic and Paralympic Games, focusing on identifying priority pathogen targets that are relevant and feasible to monitor in wastewater for these events.MethodsA list of 60 pathogens of interest for general public health surveillance for the Games was compiled. Each pathogen was evaluated against three inclusion criteria: (A) analytical feasibility; (B) relevance, i.e. with regards to the specificities of the event and the characteristics of the pathogen; and (C) added value to inform public health decision-making. Analytical feasibility was assessed through evidence from peer-reviewed publications demonstrating the detectability of pathogens in sewage, refining the initial list to 25 pathogens. Criteria B and C were evaluated via expert opinion using the Delphi method. The panel consisting of some 30 experts proposed five additional pathogens meeting criterion A, totalling 30 pathogens assessed throughout the three-round iterative questionnaire. Pathogens failing to reach 70% group consensus threshold underwent further deliberation by a subgroup of experts.ResultsSix priority targets suitable for wastewater surveillance during the Games were successfully identified: poliovirus, influenza A virus, influenza B virus, mpox virus, SARS-CoV-2 and measles virus.ConclusionThis study introduced a model framework for identifying context-specific wastewater surveillance targets for a mass gathering. Successful implementation of a wastewater surveillance plan for Paris 2024 could incentivise similar monitoring efforts for other mass gatherings globally.

Numerous SARS-CoV-2 variants are emerging as the epidemic continues, inducing new waves of contamination. In July 2023, a new variant named BA.2.86 was identified, raising concerns about its potential for viral escape, even in an immune population. The reduction in patient-centered testing and the identification of variants by sequencing means that we are now blind to the spread of this new variant. The aim of this study was to track the signature of this variant in wastewater in Paris, France. This variant showed a very rapid spread, highly correlated with national flash studies involving sequencing of clinical samples, but with a moderate impact on virus circulation. This easy-to-implement approach enabled us to monitor the emergence and spread of this new variant in real time at low cost.

The XXXIIIrd Paris Summer Olympics followed by the XVIIth Paralympics Games will take place in France, predominantly in and around Paris, from July 26 to September 8, 2024. Public health stakeholders and decision-makers are called upon to set up or strengthen surveillance systems in areas hosting Olympic or Paralympic Games (OPGs) or large-scale international competitions, the objective being to detect and manage outbreaks should they occur during that period. We undertook a narrative review of the literature so as to identify major reported infectious disease outbreaks linked with or during OPGs / international sporting events during warm seasons. Our review found that since 1992, Summer Olympic and Paralympic games and international football competitions have been associated with sporadic cases of infectious diseases, principally respiratory, gastrointestinal/foodborne, but not with any major communicable or other infectious disease outbreak. Communicable disease risks should be assessed for the population taken as a whole, an integrated ecosystem with several population compartments potentially exchanging pathogens among one another. Although the Games afford an opportunity to federate or invent new surveillance systems to fill a gap, surveillance should be based on existing medical and laboratory systems, proven tools reinforced with the necessary human and financial resources. The performance of the public health surveillance system is ultimately predicated on trust on the part of participating clinicians, policymakers and international partners.

Objectives: The aim was to estimate the effect of reported history of smallpox vaccination prior to 1980 on clinical expression of mpox. Methods: We included all confirmed mpox cases identified by the national mpox surveillance system in France between May and July 2022. Cases tested positive for monkeypox virus or orthopoxviruses by PCR. Cases were interviewed by phone using a questionnaire documenting demographics, symptoms and exposures. To estimate the effect of smallpox vaccination on the presence of marked mpox symptoms (association of fever, lymphadenopathy and extensive mucocutaneous lesions), we estimated prevalence ratios (PRs) and 95% CIs using Poisson regression models with robust standard errors. Results: There were 1888 confirmed mpox cases with date of symptom onset between 7 May and 31 July 2022. Overall, 7% (93/1394) presented marked mpox symptoms. Among patients who provided information about their vaccination status, 14% (207/1469) reported smallpox vaccination prior to 1980. The proportion of cases with marked symptoms was 2% (3/170) among those reporting smallpox vaccination prior to 1980 and 8% (76/974) among those who reported no vaccination. The proportion of marked symptoms was four times lower among cases reporting previous smallpox vaccination than in cases reporting no vaccination (PR, 0.24; 95% CI: 0.08-0.76). There was no evidence of an effect of smallpox vaccination on development of complications (PR, 0.65; 95% CI: 0.35-1.22) or hospitalization due to mpox (PR, 0.64; 95% CI: 0.23-1.80). Discussion: Our results suggest that smallpox vaccination during childhood attenuated the clinical expression of monkeypox virus infection, but there was no evidence of an effect on complications or hospitalization. Catarina Krug, Clin Microbiol Infect 2024;30:1061 (c) 2024 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Background: In European France, the bulk of malaria cases are travel-related, and only locally acquired cases are notifiable to assess any risk of re-emergence. Aims: We aimed to contribute to assessing the health impact of locally acquired malaria and the potential of malaria re-emergence in European France by documenting modes of transmission of locally acquired malaria, the Plasmodium species involved and their incidence trends. Methods: We retrospectively analysed surveillance and case investigation data on locally acquired malaria from 1995 to 2022. We classified cases by most likely mode of transmission using a classification derived from the European Centre for Disease Prevention and Control. A descriptive analysis was conducted to identify spatial and temporal patterns of cases. Results: From 1995 to 2022, European France reported 117 locally acquired malaria cases, mostly due to Plasmodium falciparum (88%) and reported in & Icirc;le-de-France (54%), Paris Region. Cases were classified as Odyssean malaria (n = 51), induced malaria (n = 36), cryptic malaria (n = 27) and introduced malaria (n = 3). Among the 117 patients, 102 (93%) were hospitalised, 24 (22%) had severe malaria and seven (7%) died. Conclusion: Locally acquired malaria remains infrequent in European France, with four reported cases per year since 1995. However, with the recent increasing trend in Odyssean malaria and climate change, the risk of re-emergence in non- endemic countries should be monitored, particularly in areas with autochthonous competent vectors. The vital risk of delayed diagnosis should make physicians consider locally acquired malaria in all patients with unexplained fever, especially when thrombocytopenia is present, even without travel history.

Background: During the 2022 mpox outbreak in Europe, primarily affecting men who have sex with men, a limited number of cases among children and adolescents were identified. Paediatric cases from outbreaks in endemic countries have been associated with a higher likelihood of severe illness. Detailed clinical case descriptions and interventions in school settings before 2022 are limited. Aim: To describe clinical characteristics of mpox cases among children (< 15 years) and adolescents (15-17 years) in the greater Paris area in France, and infection control measures in schools. Methods: We describe all notified laboratoryconfirmed and non-laboratory-confirmed cases among children and adolescents identified from May 2022 to July 2023, including demographic and clinical characterisation and infection control measures in school settings, i.e. contact tracing, contact vaccination, secondary attack rate and post-exposure vaccination uptake. Results: Nineteen cases were notified (13 children, 6 adolescents). Four adolescent cases reported sexual contact before symptom onset. Ten child cases were secondary cases of adult patients; three cases were cryptic, with vesicles on hands, arms and/or legs and one case additionally presented with genitoanal lesions. Five cases attended school during their infectious period, with 160 at -risk contacts identified, and one secondary case. Five at -risk contacts were vaccinated following exposure. Conclusion: Cases among children and adolescents are infrequent but require a careful approach to identify the source of infection and ensure infection control measures. We advocate a 'contact warning' strategy vs 'contact tracing' in order to prevent alarm and stigma. Low post-exposure vaccination rates are expected.

A 36-year-old man attended our hospital with an 8-day history of two vesiculopustular lesions on his penis (figure); he reported no fever or inguinal lymphadenopathy. The patient had no previous history of note; he had not been immunised against smallpox. Over the past 3 years he said that he regularly took pre-exposure prophylaxis (PrEP) against HIV.

Background Locally-acquired mpox cases were rarely reported outside Africa until May 2022, when locally-acquired-mpox cases occurred in various European countries. Aim We describe the mpox epidemic in France, including demographic and behavioural changes among a subset of cases, during its course. Methods Data were retrieved from the enhanced national surveillance system until 30 September 2022. Laboratory-confirmed cases tested positive for monkeypox virus or orthopoxviruses by PCR; non-laboratory-confirmed cases had clinical symptoms and an epidemiological link to a laboratory-confirmed case. A subset of ≥ 15-year-old male cases, notified until 1 August, was interviewed for epidemiological, clinical and sexual behaviour information. Association of symptom-onset month with quantitative outcomes was evaluated by t- or Wilcoxon tests, and with binary outcomes, by Pearson’s chi-squared or Fisher exact tests. Results A total of 4,856 mpox cases were notified, mostly in Île-de-France region (62%; 3,025/4,855). Cases aged ≥ 15 years were predominantly male (97%; 4,668/4,812), with 37 years (range: 15–81) as mean age. Between May and July, among the subset interviewed, mpox cases increased in regions other than Île-de-France, and mean age rose from 35 (range: 21–64) to 38 years (range: 16–75; p = 0.007). Proportions of cases attending men-who-have-sex-with-men (MSM) meeting venues declined from 60% (55/91) to 46% (164/359; p = 0.012); median number of sexual partners decreased from four (interquartile range (IQR): 1–10) to two (IQR: 1–4; p < 0.001). Conclusion Changes in cases’ characteristics during the epidemic, could reflect virus spread from people who were more to less behaviourally vulnerable to mpox between May and July, or MSM reducing numbers of sexual partners as recommended.

A cluster of three confirmed autochthonous dengue cases was detected in October 2023 in the Val-de-Marne department neighbouring Paris, France. This marks the northernmost transmission of dengue in Europe reported to date. The epidemiological and microbiological investigations and the vector control measures are described. This event confirms the need for early case detection and response to contain dengue in Europe, especially given the 2024 Summer Olympic and Paralympic Games, when millions of visitors will visit the Greater Paris area.