High viral concentrations of monkeypox were found on the surfaces of infected patients' rooms, according to a study published in Eurosurveillance. Do contaminated surfaces increase the risk of transmission?

Monkeypox: The latest on the outbreak

Monkeypox found on surfaces in infected patients' hospital rooms

Monkeypox mainly spreads through direct physical contact with an infected animal or person, but as cases worldwide continue to grow rapidly, scientists are researching other potential routes of transmission.

For the study, researchers swabbed the surfaces of rooms being used by two hospitalized monkeypox patients in Germany, including their bathrooms and the adjacent anterooms where workers would change in and out of personal protective equipment (PPE).

According to the researchers, the surfaces the patients directly touched had the highest loads of viral concentration and were primarily found in their bathrooms, particularly on the toilet seats, washbasin, and levers. The virus was also detected on the patients' chairs, the fabrics in their rooms (towels, shirts, pillowcases), and one patient's mobile phone.

In addition, the virus was found in different areas of the patients' rooms, including on the handles of the cabinets, as well as all contact points in the anterooms. The researchers believe the viral contamination on these surfaces was mainly from medical staff caring for the patients.

Do contaminated surfaces increase the risk of viral transmission?

According to the researchers, there is currently no "definite data" on what amount of viral load is needed to transmit monkeypox, but the necessary amount is believed to be substantially higher than other viruses, such as smallpox. This means that although monkeypox was found on several surfaces in the patients' rooms, infection would not necessarily occur from touching them.

"Despite high contamination with up to 105 cp/cm2 as well as the successful recovery of monkeypox virus from samples with a total of > 106 copies, our findings do not prove that infection can occur from contact with these surfaces," the researchers wrote.

However, they also noted that contaminated surfaces have the potential to be infectious, and "it cannot be ruled out that their contact with especially damaged skin or mucous membranes, could result in transmission."

Although no evidence of secondary transmission through contaminated surfaces was observed in the study, there have been other cases where individuals have been infected after interacting with contaminated materials.

For example, during a previous monkeypox outbreak in Africa, a nurse who was not wearing adequate PPE was infected with the virus after removing a patient's clothes, taking their blood, and checking their temperature. In addition, another case was reported in the United Kingdom where a health care worker became infected after changing "potentially contaminated bed linen" without adequate PPE.

According to Hugh Adler, from the department of clinical sciences at the Liverpool School of Tropical Medicine, the study's findings are "absolutely an expected development" and that "outside of very heavily contaminated areas … surfaces in the community are not likely to be high risk for transmission."

"Patients with extensive skin lesions admitted to hospital are likely to spread the highest amount of virus to the environment," he said. "Patients with milder disease might shed less; we don't know yet."

"Monkeypox viral persistence on surfaces is already well known in public health circles, and current public health guidelines for people self-isolating at home include recommendations for how to do laundry and steps to be taken to prevent transmission to household contacts," Adler said.

Overall, Adler said the study's findings are not a cause for concern, but instead help "reinforce the importance of following public health guidelines."

"This data refers to a hospital room, and may translate to the home environment (e.g., someone's bedroom while they're self-isolating) but this paper does not mean that monkeypox patients shed infectious virus into the wider environment/surfaces around the town," he added. (White, Newsweek, 7/5; European Centre for Disease Prevention and Control, EurekAlert!, 7/1; Nörz et al., Eurosurveillance, 6/30)