Monkeypox Contact Tracing and Investigation Shed New Light on Relative Risks of Monkeypox Acquisition Following Exposure

November 21, 2022

Cambridge, MA – During the 2022 global Monkeypox outbreak there have been over 80,000 confirmed infections and 52 deaths to date. Scientists’ understanding of the epidemiology of monkeypox in this outbreak continues to evolve, including the risk of transmission in both community and healthcare settings.

In May 2022, the first case of monkeypox virus infection in the United States was identified in Boston, diagnosed at Massachusetts General Hospital. The diagnosis, which was reached several days into the patient’s hospitalization, resulted in an extensive investigation across many settings. Infectious disease specialists, healthcare epidemiologists, infection preventionists, occupational health clinicians, and public health officials from Beth Israel Lahey Health, Massachusetts General Hospital and the Massachusetts’ Department of Public Health worked together to conduct the contact tracing and exposure investigation. Despite the delayed diagnosis, no secondary infections resulted from the index case. In a paper published in Annals of Internal Medicine, the scientists report on the augmented risk assessment framework they developed based on CDC guidance to assist in decision making on defining exposures, stratifying those exposures by risk, and use of postexposure prophylaxis or PEP.

“The creation of a framework for assessing specific risk scenarios permitted ease of application by employee occupational health and infection prevention staff and application across various healthcare settings,” said co-first author Sharon B. Wright MD, MPH, Chief Infection Prevention Officer, Beth Israel Lahey Health. “Public health departments and healthcare facilities should consider how these findings may inform revised estimates of exposure risk and requirements for monitoring and recommendations for PEP.”

The authors report that the patient presented over several days to multiple health care facilities in Massachusetts with progressive symptoms, which eventually prompted hospitalization. For the first five days, monkeypox was not suspected as other diagnoses were pursued, and the patient was not isolated.

A contact tracing and exposure investigation identified 166 contacts across community and healthcare settings. Four contacts were considered to be at high-risk, 49 intermediate and 113 at low or uncertain risk of contracting the infection based on the type, length and duration of their contact with index patient and, for healthcare personnel, whether they were wearing appropriate personal protective equipment at the time. All contacts were monitored for symptoms for 21 days after their last exposure.

“On the basis of this experience and published experience prior to the current outbreak, the risk of transmission in healthcare settings appears to be low. We concluded during our investigation that healthcare personnel using all appropriate personal protective equipment, in the absence of a recognized breach, should not be considered to have sustained an exposure or require monitoring during the 21-day exposure window,” said co-first author Erica S. Shenoy, MD, PhD, Medical Director of Infection Control, Mass General Brigham, Associate Chief of the Infection Control Unit at Massachusetts General Hospital and Medical Director of the Regional Emerging Special Pathogens Treatment Center at Massachusetts General Hospital.

During the investigation, individuals with high-risk exposures were offered PEP, and three elected to have it. Among those with intermediate-risk exposures for which PEP was offered as part of informed clinical decision making, two elected to receive PEP. No transmissions were identified at the conclusion of the 21-day monitoring period, despite the delay in recognition of monkeypox in the index patient.

“The time and resources required to establish exposure risk are not insignificant and involve one-on-one discussions with healthcare personnel and community contacts,” said co-senior author Catherine M. Brown, DVM, MSc, MPH, of the Massachusetts Department of Public Health. “Despite the challenges, conducting and reporting on such investigations is critical to advance our understanding of transmission risk,” added co-senior author Lawrence C. Madoff, MD, of the Massachusetts Department of Public Health.

Co-authors included Lisa A. Foster, Aleah D. King, of Beth Israel Lahey Health; Deborah A. Barbeau, Patrick S. Gordon, Preeti Mehrotra, Dana E. Pepe of Beth Israel Deaconess Medical Center; Daniel A. Caroff, Lindsey R. Kim, Shannon E. McGrath of Lahey Hospital and Medical Center; Amy Courtney, Meredith Fahey, David Hooper, Eileen F. Searle, Kimon C. Zachary of Massachusetts General Hospital; Kaitlin McDonald, Jennifer A. Shearer of Mass General Brigham; Lindsay Bouton, Melissa Cumming, Brandy Hopkins,Juliana Jacoboski, Erin Mann, Carly Perez, Jordan Schultz, Sarah Scotland Elizabeth Traphagan of the Massachusetts Department of Public Health

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