The Health Ministry is keeping an eye on a US review of whether the public should wear face masks during the pandemic.
The US Centers for Disease Control and Prevention (CDC) is reviewing new data that shows the highly infectious nature of Covid-19 means regular face mask use may help cut transmission.
It shows the coronavirus is probably three times as infectious as the flu, that many people show no symptoms for two days, and that in this time they spread the virus around.
Both the Centers for Disease Control and Prevention and the World Health Organisation have repeatedly said that people do not need to wear masks unless they are sick and coughing. New Zealand follows these guidelines.
But the CDC now is "aggressively" reviewing its guidelines on who should wear masks.
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The Director-General of Health Dr Ashley Bloomfield told a briefing in Wellington this afternoon that the experience in parts of Asia of routine face mask use by people who had common respiratory illnesses appeared to back this up.
"There's some suggestion that routine wearing of face masks by people when they're out in public may help reduce the transmission, for example if they are asymptomatic.
"So we're looking very closely at that, I'm watching that CDC review very closely."
Some of the 41 million new masks being imported by the ministry over the next six weeks could be redirected from district health boards to the general public, he said.
"It is possible yes, because the main thing would be to ensure that they are being used where they are most valued."
There was a range of views on face mask use, he said.
Other US authorities are describing routine mask use as an additional layer of protection.
China's lead Covid-19 battler, George Gao, told Science magazine several days ago that the biggest mistake the US and Europe were making "is that people aren't wearing masks".
"This virus is transmitted by droplets and close contact," said Gao, director-general of the Chinese Center for Disease Control and Prevention.
"Droplets play a very important role - you've got to wear a mask, because when you speak, there are always droplets coming out of your mouth.
"Many people have asymptomatic or presymptomatic infections. If they are wearing face masks, it can prevent droplets that carry the virus from escaping and infecting others."
Read more about the Covid-19 coronavirus:
- See all RNZ Covid-19 news
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- Covid-19 symptoms: What they are and how they make you feel
- Touching your Face: Why do we do it and how to stop
- Scientific hand-washing advice to avoid infection
- Coronavirus: A glossary of terms
- The Coronavirus Podcast