Dr. David Nabarro:

I will start by addressing when people are most likely to transmit Covid-19. The answer is in the day or so before they develop their symptoms. This is one of the reasons this is a hard virus to deal with. SARS tended to be symptomatic at transmission but Covid-19 seems to be a bit more pre-symptomatic transmission. The committee might know there is quite a bit of debate about people who never have symptoms but who can transmit the virus. If that is the reality, that people just before they are seen to get the disease are still potentially quite infectious, then I totally agree with the Deputy that the comprehensive package is important.

On Deputy McGuinness's point, yes, face masks have been a super important part of the comprehensive package in east Asia. Deputy O'Rourke called it the "cumulative playbook". I like that legislators are recognising it is not one or the other, it is all of the different pieces together. We cannot pick out any single approach that makes all the difference. Face protection does seem to be a part of it.

On the 1 m versus 2 m issue, I will say it again but I will try a slightly different way. Essentially, if people want to be really sure about not getting infected by somebody with Covid-19, then they should stay a long way away from the person, possibly 3 m or 4 m. When a person is coughing one does not know whether a droplet will fly across in the air, which we call aerosolization, and one may just happen to have the bad luck to get it. I have a very close friend who believes she caught her Covid-19 in a supermarket in Brighton where there was aerosolized transmission. To be super sure, then people need to be quite a long way away. The closer one is to the person who has Covid-19 the more likely one is to get infected.

Our current advice is that at 2 m, one is between 85% and 95% likely to be protected but there is still an outside chance that one may contract the virus. At 1 m, the protection drops to between 70% and 80%. Of course, the likelihood of contracting the virus increases if it is a closed environment. One of the things we have found is that karaoke bars are particularly problematic because people there are in close proximity and, in addition, they sing and shout. We have found that when people sing and shout, particularly very loudly, such as when belting out a song, they are able to transmit much more easily. It is all a question of risk and it very much depends on how people behave.