For the last two years, one question has been on everybody's lips: "When do we get back to normal?" Some countries, like the UK, have tried and failed to lift all their Covid-19 restrictions. Many in Europe have been forced to ramp them up. Others, like ChinaA country in East Asia, home to 1.4 billion people., continue to hide from the virus behind closed borders, locking down whole regions whenever a handful of cases crops up.

But in ScandinaviaThe name given collectively to Denmark, Norway and Sweden, three of the northernmost countries of Europe. The three countries have similar languages and political systems., "normal" starts again tomorrow, as Sweden lifts all mandatory Covid-19 regulations. It joins Denmark and Norway in a new approach to the pandemic. People will only be encouraged to stay at home if they are ill. No more vaccine passportsMany countries have introduced passes based on vaccination status or recent tests to enter some public spaces and business., curfews, limits on socialising - and no more face masks.

About time, say some critics. Among them is author Ian Miller, who argues that masks have been a collective delusion since day one.

He points out that in the first months of the pandemic, public health experts across the Western world insisted that masks did nothing to stop the spread of the virus. He thinks after they changed their advice, they never bothered to check whether or not masks actually work.

He argues, the evidence suggests they do not. For example, the city of Los Angeles has had a mask requirement for most of the pandemic. Yet it has had higher infection rates than neighbouring Orange CountyA region in southern California forming part of the Los Angeles metropolitan area., which has had no mask requirement for the last year.

Others think this does not prove much. The population densityA measure of the number of people within a particular area. It is usually measured by people per square kilometre. of Orange County is about half that of LA. All viruses spread more easily in densely-populated areas, because people simply have more contact with each other. Studies comparing the impact of masks in more similar settlements suggest they do have an impact on the spread of the disease.

The stakes in this research are high. If other countries follow Scandinavia in ditching masks, they cannot assume they will fare just as well. Sweden, Denmark and Norway all have low population densities, high vaccination rates and resilient, well-funded public health systems. 

These conditions make it harder for the virus to spread - and easier for the countries to deal with a sharp rise in infection rates. Most other Western countries are more densely-populated, have fewer triple-jabbedMost Western countries have rolled out third booster jabs, intended to increase people's immunity to the Omicron variant. citizens and do not invest as much in their health systems. If abolishing mask requirements does lead to a spike in infections they will struggle to deal with it.

Still others suggest that even if masks did have no direct effect, they could still serve some purpose. Wearing a mask is a reminder to keep abiding by other Covid-19 measures, like ventilating spaces and maintaining social distancing. And it reassures others that we are taking these duties seriously.

Yes: Masks have become a culture warAn internal conflict over a country's values. The term is a translation of the German Kulturkampf, originally referring to a struggle between the state and the Catholic Church in the late nineteenth Century. issue, dividing countries down the middle. Now it seems they have done little to stop the spread of the virus. They have done more harm than good.

No: Although a lot of health experts initially got it wrong, there is solid evidence that masks do slow the spread of Covid-19. They have likely saved millions of lives, and we should keep wearing them.

Or... The main benefit of masks is not restricting the spread of the disease, but acting as a social signal to others that we take their health seriously. They helped us stay united in the dark days of the pandemic.

China - A country in East Asia, home to 1.4 billion people.

Scandinavia - The name given collectively to Denmark, Norway and Sweden, three of the northernmost countries of Europe. The three countries have similar languages and political systems.

Vaccine passports - Many countries have introduced passes based on vaccination status or recent tests to enter some public spaces and business.

Orange County - A region in southern California forming part of the Los Angeles metropolitan area.

Population density - A measure of the number of people within a particular area. It is usually measured by people per square kilometre.

Triple-jabbed - Most Western countries have rolled out third booster jabs, intended to increase people's immunity to the Omicron variant.

Culture war - An internal conflict over a country's values. The term is a translation of the German Kulturkampf, originally referring to a struggle between the state and the Catholic Church in the late nineteenth Century.