New HPRU-EZI study finds that monkeypox can spread widely within specialist hospital isolation rooms

Fri, 14 October 2022

The UK Health Security Agency (UKHSA) recommends that patients with monkeypox who have severe disease requiring hospital admission are cared for in isolation rooms, with infection prevention and control (IPC) precautions that aim to contain potentially infectious virus within the room and protect staff who enter. However, to date it has been unclear whether these measures are proportionate to the potential virus exposure risks.

To investigate this, researchers from the Liverpool School of Tropical Medicine, the University of Oxford’s Nuffield Department of Medicine and the UKHSA conducted a study which collected samples from the rooms of patients hospitalised with monkeypox. The findings have been published in The Lancet Microbe.

The research team assessed the extent of virus shedding onto surfaces in specialist isolation rooms containing patients admitted to hospital for the management of severe monkeypox. They also investigated whether the virus was detectable in air samples from the rooms.

The researchers found that viral DNA shed by the patients could be found on multiple surfaces throughout the isolation rooms (56 (93%) positive by PCR out of 60 samples). Monkeypox virus DNA was also found on personal protective equipment (PPE) worn by healthcare workers caring for these patients, and in the anterooms where they remove their PPE. Monkeypox virus DNA was also detected in five out of twenty air samples taken within these isolation rooms.

Changing bed linen was an activity particularly associated with detection of monkeypox virus DNA in air samples in the room. This suggests that viral particles, probably in shed skin particles, can become suspended in the air when bed sheets are changed. Monkeypox virus capable of replicating in cells under laboratory conditions (an indicator that the virus could infect other people) was identified in two of four PCR-positive samples selected for virus isolation. This includes air samples collected during the bed linen change.

Lead author, Dr Susan Gould, from the Liverpool School of Tropical Medicine, said: ‘Our results found that changing a patient’s bedding appears to be particularly associated with an increased ability to detect monkeypox virus in air samples. In 2018, a UK healthcare worker was thought to have developed monkeypox after being exposed to the virus while changing a patient’s bedding, before monkeypox had been considered and diagnosed. Our results suggest that changing bed linen used by hospitalised patients with monkeypox does indeed increase the risk of exposure to virus, by disturbing virus on bed linen and allowing it to be suspended in the air.’

In addition to detecting virus DNA, the researchers were able to isolate replication-competent virus in some surface and air samples. The results show, for the first time, that monkeypox virus in some air samples taken around patients hospitalised with monkeypox is capable of replicating in cells and is not just ‘dead’ virus. Dr Gould said ‘These results suggest that monkeypox virus shed into a hospitalised patient’s environment poses an infection risk that needs to be managed.’

Senior author on the paper, Dr Jake Dunning, of the University of Oxford’s Nuffield Department of Medicine and the Royal Free London NHS Foundation Trust, said: ‘It is important to note that detection of virus, even when demonstrated to be infectious, does not necessarily mean that exposure to the virus in real life would result in infection of the exposed person. However, it does reveal a potential transmission risk and one that is reasonable to control in hospital settings. Our results confirm that the strict IPC measures we follow in specialist infectious diseases centres are necessary and appropriate.’