Pre- and asymptomatic viral shedding in high-risk contacts of monkeypox cases: a prospective cohort study

Epidemiological data suggest that clade IIb monkeypox virus (MPXV) is readily transmitted during sexual contact, even before symptom onset. However, presymptomatic shedding of MPXV remains to be demonstrated. Here, we prospectively followed up 25 individuals after high-risk exposure to MPXV. Daily anorectal, genital, and saliva samples and weekly blood and oropharyngeal samples were collected along with clinical information. During follow-up, 12/18 (66.0%) sexual and 1/7 (14.0%) non-sexual contacts showed evidence of MPXV infection by PCR, five of whom had low viral loads and no typical MPXV symptoms. In 5/6 (83.3%) patients with typical symptoms, viral DNA was detected as early as four days before symptom onset and in three of them, replication-competent virus was found. These findings emphasize the high risk of MPXV transmission during sexual contact and confirm the existence of presymptomatic viral shedding of MPXV. Sexual contacts of an MPXV-infected partner should abstain from sex irrespective of symptoms. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Protocols ### Funding Statement This work was funded by the Agency of Care and Health and the Department of Economy, Science, and Innovation of the Flemish government. IB and EB are members of the Institute of Tropical Medicine's Outbreak Research Team, which is as also financially supported by the Department of Economy, Science, and Innovation ### 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: The Institutional Review Board of the Institute of Tropical Medicine, Antwerp, Belgium (1604/22) and the Ethics Committee of the Antwerp University Hospital, Belgium (3571) gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the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 and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The data supporting the findings of this publication are retained at the Institute of Tropical Medicine (ITM), Antwerp and will not be made openly accessible due to ethical and privacy concerns. According to the ITM research data sharing policy, only fully anonymised data can be shared publicly. The data are de-identified (using a unique patient code) but not fully anonymised and it is not possible to fully anonymise them due to the longitudinal nature of the data. Data can however be made available after approval of a motivated and written request to the ITM at ITMresearchdataaccess{at}itg.be. The ITM data access committee will verify if the dataset is suitable for obtaining the study objective and assure that confidentiality and ethical requirements are in place.