Lesson plan

Outbreaks of infection are to epidemiologists and microbiologists as earthquakes are to seismologists. Studying Covid outbreaks has given us an enormous amount of information about how the virus spreads, and scientists have been very busy putting such information into the public domain; more than 125,000 scientific papers about Covid were published during the first year of the pandemic.

The information from them lets me assure A Lewis (Letters, 30 January) that we know for certain that a much more important transmission route for the virus is by aerosols that travel in the air rather than exhaled droplets that fall quickly to the ground, and that touching contaminated door handles is much less important than either. Studies of the enormous outbreak on the Diamond Princess cruise liner in February 2020 moored off Yokohama (712 cases,14 deaths) gave such information very early in the pandemic, for example.

The Diamond Princess also showed the importance of age as a risk factor for lethality, and that infection without symptoms was common. An important remit of the Covid public inquiries is to investigate how effective the authorities were in using this kind of information to develop and implement virus control policies.

I agree with A Lewis that by rectifying any shortcomings we could be better prepared when the next pandemic strikes. But as the chair of two inquiries into lethal outbreaks (E.coli in Scotland in 1996 and South Wales in 2005) I am a cynic, my inquiries demonstrating that while we are good at learning lessons, we are just as good at forgetting them. Hugh Pennington

Aberdeen