David McCoy (Faith in coronavirus modelling is no substitute for sound political judgment, 10 April) says: “Epidemiological modelling has played a disproportionately influential role in shaping the UK’s strategy and plans … and none can avoid the fact that decision-making must also be informed by people with relevant expertise and experience, and by the facts on the ground.”
I taught bacteriology in Manchester Medical School for 35 years and the first practical classes started with these sentences: “With bacteria all things are possible, bacteria don’t read textbooks. What you objectively and accurately record is what they do. What you expected or wanted them to do are questions that may or may not be answered.”
So, too, with viruses. Instead of trying to make the viruses’ behaviour fit magic curves, we must change to fit the behaviour of the viruses, which is why personal protection is so vital and works. Look at the graphs, follow the science. The safety factor difference between highest spec FFP3/N95 and standard surgical mask (EN14683), except in high virus density situations such as intensive care units, is small (see Leung et al. Nature Medicine).
The statement that the general wearing of masks has no part to play in ending the epidemic is false. Prof McCoy’s piece should have been headlined “Modelling is no substitute for scientific acuity”. Politics works in a very different way from science.
Dr Louis B Quesnel
Salford, Greater Manchester
• Re Richard Horton’s article (Coronavirus is the greatest global science policy failure in a generation, 9 April), good drivers anticipate the road ahead, whereas drivers who have been drinking can only react to the stretch of road they see ahead. Dr Horton is right that we were poorly prepared in December because of a failure of science policy. As a public health trainer and planner, I am personally responsible for this failure – I knew there were holes in our planning, especially in training for emergencies (see my 2019 note in the BMJ).
If I live through the crisis, I dedicate myself to training the next generation with more foresight, imagination – and humility.
Woody Caan
Retired professor of public health, Duxford, Cambridgeshire
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