Hospital patients 'more likely to be infected with Covid-19 by other patients'

Most patients who contracted COVID-19 while in hospital did so from other patients rather than from healthcare workers, according to researchers at the University of Cambridge and Addenbrooke's Hospital.

Out of 22 cases where patients were infected in hospital, 20 of these were the result of the virus spreading from patients to other patients.

The study into how infections spread in hospital analysed data from the first wave of the pandemic last year.

Scientists say it proves why it is still important for patients to be routinely tested upon admission.

While hospitals aim to keep infected and non-infected individuals apart, it is more difficult when the number of infections is high.

The high level of transmissibility of the virus and the potential for infected individuals to be asymptomatic added to the challenge for hospitals.

The study found contrasting results, however, among healthcare workers.

They were found to be almost just as likely to be infected by patients as they were by other healthcare workers.

This was one of the reasons there was an upgrade in the respiratory protection worn by healthcare workers in COVID-19 wards at CUH.

The study also provides detail showing that a minority of individuals can cause most of the transmission.

There was also a trend towards individuals either infecting no one else, or infecting multiple other people - just over 20% of patients caused 80% of the infections.

This phenomenon is sometimes called 'superspreading' and can make infection control very challenging.

Whether or not an individual can be identified in advance as being more or less likely to pass on the virus is an ongoing topic of research.

The research was funded by COG-UK, Wellcome, the Academy of Medical Sciences, the Health Foundation and the NIHR Cambridge Biomedical Research Centre.