Coronavirus panic: Face masks sell out, but do they work?

Pharmacists say they're almost instantly selling out of face masks amid panic over the coronavirus, but experts and health authorities say the devices won't be of much help.

With three cases confirmed in New Zealand, residents have been rushing to the chemist to get hold of surgical mouth-covering masks as a precaution.

Staff at the pharmacy in the Countdown in the Wellington suburb of Newtown said their small orders, about three boxes at a time, were selling out within an hour of arriving.

A sign on its register on Tuesday morning read: "Stocks may arrive later this week."

"The suppliers have a limited amount and all the pharmacies are ordering them," a staff member who asked not be named said.

"[I haven't seen people] this crazy about buying masks before."

He said most of the customers they were seeing were preparing to travel overseas.

It's a story that's been common around the country in recent days, with pharmacies in Auckland reporting similar situations.

But University of Auckland pathology associate professor Simon Swift said cheap store-bought face masks were unlikely to provide much protection, because they did not seal around the face and were often reused.

"I'm sure they provide more protection than breathing in the air … but it would a naïve assumption to think: 'It's alight, I've got my $5 face mask, I'm protected," he said.

Swift said the virus could still get on other places on people's skin and when removing the mask, people would touch the outside, where the virus could potentially be sitting.

"I personally haven't rushed out to buy one," he said.

If you are thinking of pandemic prepping, you are too late, they are sold out of masks already at Countdown pharmacy Newtown pic.twitter.com/uGSJ94Ciao

— Lynn Grieveson (@LynnGrieveson) January 27, 2020

Cambridge University consultant virologist Chris Smith went further, saying most of the surgical masks commonly sold were "absolute rubbish".

"They do absolutely nothing," he told Radio NZ.

"The ones we're talking about, that you go and buy off a street vendor and you wear on the underground or tram or on the streets, those are absolutely useless."

Smith said properly-fitted prophylactic masks from hospitals could help, because they formed seals around the face and were accompanied by eye protection.

But he said standard surgical masks were only beneficial in making people feel better about having done something, and warning others to stay away from those wearing them.

New Zealand's director-general of health, Ashley Bloomfield, did not make much of the devices either.

"You can use a face mask if you like, but it is not really any protection," he said.

He said the Ministry of Health was promoting the "staples" of outbreak prevention, including hand cleaning, staying at home when sick and covering coughs and sneezes.

The ministry had a contract that allowed it to ramp up production of masks for use by District Health Boards as part of its response, Bloomfield said.