While New Zealand has been lauded for its zero-tolerance response to Covid-19, it arrived late to the mask party. Science reporter Jamie Morton looks at where our new policy has paid off elsewhere in the world.
Around the globe, mask policies range from optional to absolute.
But there are few countries without any determined position, as New Zealand has had for much of this year.
Even as early as May, nearly 90 per cent of countries had rules or recommendations in place.
African nations now have blanket mask mandates in place, with the exceptions of Niger and South Sudan, where they're required only in certain spaces; and Eswatini, Malawi, Tanzania, Somalia, Eritrea, Togo and Libya, where they're recommended or not required.
In keeping with long-standing cultural practice, most Asian nations either require them in all public spaces (Indonesia, the Philippines, Thailand, Laos, India and Bangladesh) or in certain places (Malaysia, Vietnam, South Korea).
In Europe, people must wear masks in public in Spain and France and in select spaces elsewhere.
Only in Ireland, Slovakia, Belarus, Lithuania, Estonia and most Scandinavian states are they not compulsory anywhere.
They also now must be worn in certain places - but not everywhere - in Australia, Turkey, North America and South America, except inBolivia, Peru, Eucador, Colombia, Venezeula, Guyana and Suriname.
Some of the strictest mandates are found in Qatar - where anyone found not be masked while out and about can be jailed for up to three years or fined as much as NZ$84,000 - and Ghana, where violators can face up to 10 years in jail.
In contrast, Sweden's controversial chief epidemiologist Anders Tegnell has discouraged their use, going as far as saying they could be dangerous - a view counter to that of the World Health Organisation's (WHO) recently-adopted official stance.
The United States Centers for Disease Control and Prevention (CDC) has recommended since early April that people wear cloth face coverings in public.
State policies didn't always match up with people's willingness to mask up.
One analysis of evidence by Our World In Data, showed that, as at July, those countries with the highest proportion of people saying they always wore masks outside the home were Singapore (93 per cent), the Philippines (92 per cent), United Arab Emirates (89 per cent), India (88 per cent) and Spain (87 per cent).
Despite not having blanket mandates in place, mask-wearing outside the home was similarly high in Brazil (90 per cent), Mexico (86 per cent) and Italy (79 per cent).
At the other end of the scale, there was dramatically less uptake in the UK (22 per cent) and Australia (12 per cent), along with Finland (1 per cent), Norway (3 per cent), Sweden (3 per cent) and Denmark (1 per cent), where an order for masks on public transport has just come into force.
While a culture shock for Kiwis, there are already positive signs we've embraced the practice, with Auckland Transport reporting nine out of 10 passengers were wearing masks upon the city's return to level 2 today.
At a lower level, there have been debates within countries about what types of masks should be worn, whether they should be used if physical distance is already in place or if people out exercising need to don them.
While the WHO didn't recommend widespread of non-medical cloth masks among the public for control of Covid-19, citing "limited evidence" on their effectiveness, the case was different for crowded and closed-in places.
"For areas of widespread transmission, with limited capacity for implementing control measures and especially in settings where physical distancing of at least one metre is not possible – such as on public transport, in shops or in other confined or crowded environments – WHO advises governments to encourage the general public to use non-medical fabric masks."
There are lots of things that we want to be doing right now, but they aren't necessarily what we need to be doing right now - please make good choices.
— World Health Organization (WHO) (@WHO) July 15, 2020
There's so much you can do to protect yourself from getting infected and from passing #COVID19 on to others.
-Dr @mvankerkhove pic.twitter.com/0hyAivUelA
Epidemiologists say it's difficult to tease out the specific impact mask-wearing has made amid other measures in countries' Covid-19 responses.
But some observational studies have highlighted benefits.
In June, researchers from the Chinese University of Hong Kong shared findings from an analysis of how public interest in face masks may have affected the severity of Covid-19 epidemics and potentially contained the outbreak in 42 countries in six continents.
The authors noted that, "in many Asian countries like China and Japan, the use of face masks in this pandemic is ubiquitous and is considered as a hygiene etiquette, whereas in many Western countries, [their] use in the public is less common."
There was a clear negative correlation between the awareness or general acceptance of wearing a face mask and its infection rates, they reported.
Otago University's Professor Nick Wilson singled out Hong Kong, where, among other preventive steps learned from the SARS crisis of the early 2000s, the use of face masks helped keep the virus out of care facilities.
Elsewhere, Wilson saw former Eastern Bloc countries like Slovakia and the Czech Republic as exemplars.
Prague became one of the first European centres to require mandatory mask-wearing, while the Czech Government pushed the practice through videos.
In an op-ed in USA Today, Steve Kashkett, a scholar at Prague's Anglo-American University, wrote how the order was taken up widely and, within two weeks, daily Covid-19 case numbers dropped throughout the country.
The Czech Republic was soon able to relax restrictions - including mask-wearing - but has seen the step as a point of pride. In May, its national museum began exhibiting masks that were made during the pandemic.
Back in March, Czech Prime Minister Andrej Babis even targeted US President Donald Trump with a tweet to "try tackling the virus Czech way", adding that even a cloth mask could make a difference.
Neighbouring Slolvakia similarly acted early, making masks compulsory in public transport in its largest cities on March 16.
Influential US magazine The Atlantic hailed the example set by the country's Prime Minister Igor Matovic and Health Minister Zlatica Puskarova in modelling masks on Slovak TV.
Otago's Professor Michael Baker also cited evidence from observational research out of Germany.
"They phased-in mandatory masking in different states of Germany at different times but it was found that mass-masking appeared to be associated with a 40 per cent drop in infection rates," he said.
Danish and German researchers focused on the city of Jena, where facemasks were made mandatory on April 6, and noted a 25 per cent drop in case rates over 20 days.
"Comparing the daily growth rate in the synthetic control group with the observed daily growth rate in Jena, the latter shrinks by around 60 per cent due to the introduction of facemasks," they reported in their discussion paper for the Institute of Labour Economics.
"This is a sizeable effect. Wearing facemasks apparently helped considerably in reducing the spread of Covid-19."
There was also the experience of Kansas in the US, where 15 counties that retained a state mask mandate had seen a rapid drop in cases, while 90 counties that abandoned it saw no such fall.
"So I think the observational evidence is now very strong," Baker said.
"Back in Hong Kong, for instance, if you look at events where people were masked, versus events where they weren't, the former very much had a lower rate of subsequent outbreaks."
New Zealand's new rules meant that, as from this week, all people, unless exempted, must wear masks or face coverings on buses, trains, ferries and on all flights at alert level 2 and above.
The Government was also advocating - but not requiring - mask use more generally.
"Basically, when you step out of your home ... we are asking you to wear a mask," Prime Minister Jacinda Ardern said on Sunday.
She would not rule out mandating the use of masks if people don't wear them.
Baker saw a need to go further with masks in schools under level 2.
He also thought workers should also wear masks in meetings and in any other situations where people are less than one metre apart indoors - creating a kind of "alert level 2.5" particularly in Auckland, where the virus was still in the community.
Current alert level 2 guidance was that people should stay 1m apart indoors and 2m apart outdoors.
Baker said the rationale was to stop people spreading the virus to other people.
"If everyone is wearing masks, that is a far more effective way of dampening down transmission risk."
That was in line with a message now being used around the world: "Your mask protects me, my mask protects you."
Police Assistant Commissioner Richard Chambers said officers today only needed to speak with a "very small" number of people not following the mask rules, adding that police were generally "pleasantly surprised" at the high compliance.
"For those people who are struggling with why masks are mandatory, I would encourage you to reflect on the damage this pandemic has done overseas," he said.
"We are in a good position in New Zealand and it's important we continue to do the right thing."
Asked how soon the Government might start taking a punitive stance on people who refused to follow the new rules, Health Minister Chris Hipkins pointed to the high uptake on public transport in Auckland, along with "about 50 per cent" of people in the streets wearing masks.
"I think people are taking this seriously, so, look, we'll keep it under review," he said.
"At this point, I'm confident an educate-and-inform approach is working."
Donovan Duff was already serving a life sentence. He was handed another one today.