Professor Anthony Staines:

One of Professor Heneghan’s colleagues, Professor Trisha Greenhalgh, has conducted a systematic review of the evidence for masks. Unlike Professor Heneghan, I make my living analysing and interpreting observational data. I am extremely familiar with what one can and cannot usefully do with it in public health. I am moderately convinced by the evidence.

The evidence that masks protect a person from infection, particularly this type of mask or the cloth masks some members are wearing, is very low but the evidence that they reduce spread from an infected person is much better.

In terms of evidence, as far as I know there are no clinical trials, although I am aware there is one in Denmark - Professor Heneghan mentioned it - that is proceeding. We may have more evidence later in the year. Anyway, it is noteworthy that in many of the countries where this virus has been most effectively controlled people wear masks for other reasons. The view in most of the public health community - the evidence as reviewed by Professor Heneghan's colleague supports the view - is that this is a worthwhile effort. It has a modest effect on the risk of a person spreading the virus to other people. That is desirable. Again, it is part of a spectrum of imperfect measures. It is by putting many imperfect measures together that we achieve positive results. That is my 2 cent.