Real world evidence that masks work
In the midst of questions about the value of face masks in COVID-19, one hospital in the UK did a simple practical analysis. They found that even with active infection of staff, there was no transmission.
They chose a ward (for 8 weeks) where all patients transferred were swabbed for COVID prior to being moved. It was an attempt to create a clean area.
All staff on the ward (doctors, nurses, healthcare assistants, therapists, porters etc) had to wear masks for the full duration. Every new person to the ward had a temperature check prior to entering.
Staff were then swabbed weekly over the 8 weeks (not everyone was fully compliant) but overall there was good engagement.
The most interesting finding over the 8 weeks was that one member of staff was found to be positive for COVID-19 but it had not been transferred to any others.
Simple face masks can make a huge difference to transmission of infection.