Human-to-Human Transmission of Monkeypox Virus, United Kingdom, October 2018

Aisling Vaughan; Emma Aarons; John Astbury; Tim Brooks; Meera Chand; Peter Flegg; Angela Hardman; Nick Harper; Richard Jarvis; Sharon Mawdsley; Mark McGivern; Dilys Morgan; Gwyn Morris; Grainne Nixon; Catherine O'Connor; Ruth Palmer; Nick Phin; D. Ashley Price; Katherine Russell; Bengu Said; Matthias L. Schmid; Roberto Vivancos; Amanda Walsh; William Welfare; Jennifer Wilburn; Jake Dunning


Emerging Infectious Diseases. 2020;26(4):782-785. 

In This Article


Cases of human monkeypox outside Africa are rare; in the United Kingdom, the likelihood of travel-associated monkeypox cases is low.[10–12] To our knowledge, human-to-human transmission of monkeypox outside Africa has not been reported, and human-to-human transmission of the West African clade has been reported for Nigeria only.[4] Such transmission may occur through close contact with skin lesions of an infected person, via fomites, or by exposure to large respiratory droplets during face-to-face contact.[1] The transmission reported here occurred from a patient with a travel-associated case to an HCW. The only exposure risk identified during assessment of patient 3 was the changing of potentially contaminated bedding, when patient 2 had multiple skin lesions but before a diagnosis of monkeypox had been considered. The use of standard PPE may not have afforded sufficient protection against monkeypox, particularly if skin lesion debris containing virus had been disturbed and inhaled when bedsheets were changed.

Although patient 3 received postexposure vaccination before symptom onset, vaccination was >4 days after the most recent exposure to patient 2. The optimal timing for postexposure vaccination with Imvanex remains unknown, and the postexposure window period chosen for this incident was informed, in part, by that used during the US outbreak in 2003.[6] Patient 3 may have been vaccinated too late to prevent monkeypox.

During this incident, the risk to the public was determined to be very low because effective human-to-human transmission requires close contact with an infected person or virus-contaminated materials. Regardless, monkeypox is considered an HCID in England because it meets the UK criteria.[13]

Monkeypox cases associated with travel to Nigeria have subsequently been detected in Israel[14] and Singapore.[15] Although monkeypox is rare outside disease-endemic countries in Africa, this incident illustrates the need to be aware of monkeypox as a reemerging and travel-associated infection. Clinicians should consider a potential diagnosis of monkeypox early for patients with compatible symptoms and potential exposure risks, including recent travel to a disease-endemic country. In healthcare settings, implementation of appropriate infection prevention and control precautions as soon as monkeypox is suspected will help prevent secondary transmission.