Market a 'transmission risk': Epidemiologist Michael Baker


One of New Zealand’s top epidemiologists has welcomed news masks are now mandatory.

Speaking to Mountain Scene yesterday, University of Otago professor Michael Baker says because Covid-19’s airborne, masks are the cheapest, fastest and easiest way to prevent spread.

As of 1pm yesterday there were seven cases of community transmission of the dreaded Delta strain in Auckland, rising to 10 by last night.

By this afternoon, that number had increased to 21 – all in Auckland.

The government’s anticipating cases to reach about 120.

Masks became mandatory at 11.59pm last night for anyone over the age of 12 visiting an essential service, or staff working at essential services, bus and taxi passengers.

Police have been given powers to issue infringements to anyone who’s non-compliant.

Baker says while the term ‘‘airborne’’ is thrown around a lot, it’s important for people to understand what that means.

‘‘It [Covid] behaves more like the highly-infectious diseases like chickenpox and measles.

‘‘If something’s droplet-borne, which is what people thought early on with this, then the one-metre, two-metre rule might mean something.

‘‘Once something’s airborne, that rule is not enough.

‘‘Everyone has to be wearing a mask, particularly for source control, because if you’re wearing a mask you’re not firing out those aerosols as much.

‘‘It gives you some protection if you’re wearing a mask, but the main thing is to stop it at source.’’

Baker also believes the government needs to mandate use of the Covid-19 tracing app.

‘‘It just has to be mandatory to scan in to indoor environments and high-risk areas,’’ he says.

‘‘All the effort they’ve gone to develop an app and encourage people to scan-in to indoor environments, we’re missing the benefit of that.

‘‘That gives you a huge head-start with this virus.

‘‘Otherwise contact tracing is severely hampered, because you’re just not getting on top of it fast enough.’’

But, he warns, we may be in for the long-haul again with lockdown.

Cases identified since Tuesday are ‘‘the easy ones to find’’.

‘‘The hard cases are the ones we can’t see, because there’s no starting point.

‘‘You’ve got to wait for them to get sick, come forward and be tested.

‘‘This is where patience is required.

‘‘You have to wait until you’ve identified some more cases in the community so you can reconstruct what happened, or you might just find that luck’s on our side and there
aren’t more cases, they extinguish themselves for various reasons.’’