Professor Philip Nolan:

The virus is extraordinarily stable. Viruses mutate all the time but this one is not doing so to any great extent. The first piece of news is that any change in the behaviour of the disease in the population is due to the behaviour of the population and not the behaviour of the virus. We are also learning about the circumstances in which the virus is transmitted. It transmits very strongly in households, where the attack rate is between 20% and 30%. That is probably lower than one would expect.