As the coronavirus pandemic rages unabated, nations around the world have started looking at each other to understand how they might impede the virus' spread.
Some experts say customs and social habits in Japan such as wearing face masks during seasonal flu outbreaks, bowing rather than handshaking, and removing shoes at home might play some role in hindering transmission of the virus, although to what extent is still unknown.
But even as the scientific evidence remains pending, populations in Western countries have embraced at least one habit -- the donning of face masks in public -- that just months earlier they had seen as a quirk of Japanese or East Asian behavior.
At the same time, Japan's apparently robust practices of social hygiene could have a downside, too -- the lack of urgency with which Japan is embracing social distancing, possibly due to overconfidence in the protection afforded by its hygiene habits.
Wakaba Fukushima, a professor at the Osaka City University Graduate School of Medicine in the Department of Public Health, said in an email to Kyodo News that particular social customs found in Japan and other East Asian cultures are "potentially effective in fighting the spread of coronavirus."
"However, results have not been reported, and we do not know at present to 'what extent' it might be valid based on proper epidemiological research, such as for example comparing the differences in infection rates and morbidity rates of people who practice these customs against those who do not," she said.
Josh Santarpia, an associate professor of pathology and microbiology at the University of Nebraska Medical Center and research director of Countering Weapons of Mass Destruction at the University of Nebraska's National Strategic Research Institute, acknowledged such Japanese customs "probably didn't hurt."
"Rigorous hygiene practices are very important to preventing the spread of disease, so anytime these practices are already ingrained it helps," said Santarpia.
But he added that there were dangers in the adoption of mask-wearing by populations unaccustomed to it. In the United States, people frequently touch or adjust them, posing significant contamination risks. To have a "positive effect," people need to "wear them properly," he said.
Experts have warned about how the coronavirus can cling to non-human surfaces, such as keyboards, doorknobs, countertops and even cardboard boxes, and some are now acknowledging what might seem obvious: it could last for days on the soles of your shoes.
That said, Dr. Amira Roess, a professor of global health and epidemiology at George Mason University, says person-to-person transmission through "respiratory droplets" poses a much higher risk of infection than from contaminated surfaces.
So what explains the discrepancies in confirmed infection and death rates among countries of similar socioeconomic levels? Is it an issue with cultural norms helping slow the spread of the disease, implementing proper testing protocols or other underlying factors?
("The Genkan is a traditional Japanese entrance for a house or apartment. The main function of a genkan is for the removal of shoes before entering the main part of the house.)
In Japan, the confirmed rate of infection has been low thus far -- about 72 confirmed cases per million people in a population of 126 million, according to data from the European Centre for Disease Prevention and Control and the United Nations as of April 17.
One factor that may be keeping the figure low is Japan's modest testing rate compared with other countries. As of Thursday, Japan had tested about 100,000 people, or a rate of 0.8 tests per 1,000 people, compared with over 540,000 tests (10.46/1,000) in South Korea, according to Our World in Data.
But even taking that into account, the comparison with infection cases in other developed countries -- over 2,000 per million people in the United States and 3,900/million in Spain -- is stark, especially considering Japan's huge population of elderly people, who are seen as more susceptible to the virus.
When celebrities in Japan call on fans on social media to take precautions against the virus with protective measures, they generally appeal for people to just do more of what they are already used to.
"Let's strive to practice our everyday customs of gargling and handwashing, especially when we go into large crowds. Protection starts with small things. I don't doubt this," actor Koji Matoba wrote on his official blog on Jan. 30.
Rena Kato, a member of the female idol group AKB48, posted on Twitter the same day, "It pains me that our New Year handshaking fan event had to be canceled. Everyone, please take care of your health. Wash your hands and gargle! And don't forget your masks!"
The question of why Japan remains one of the least impacted countries by COVID-19 has also been a talking point on social media.
Some posters have pointed to a list of personal hygiene norms, such as face masks worn zealously during the flu season, the use of toilet bidets, and baths taken almost daily.
The frequent washing of hands, use of oshibori (hot towels) for cleansing the hands and face at restaurants, and the custom of bowing, instead of handshaking, cheek-kissing or other forms of physical contact, were brought up as a type of baked-in "social distancing" pervasive in society long before COVID-19 started making headlines.
Although people may squeeze onto rush-hour trains, there is very little talking among many of the masked commuters, who are told in repeated public announcements to refrain from chatting on their cellphones, which is considered rude.
Even so, skepticism was also in evidence on social media about Japan's relatively low coronavirus numbers, with about 10,000 confirmed cases and around 200 confirmed deaths reported by Japan's health ministry as of April 17.
Experts point out that cases of COVID-19 in all countries have been undercounted to some degree because of limited testing.
"One of the biggest challenges with comparing countries, and even cities, is that testing protocols and test kit availability are different everywhere," said Roess.
But while testing protocols affect official government tallies, the culture around trusting the government and following its recommendations and the infrastructure of the health care system likely play key roles, too, she said.
On Thursday, Tasuku Honjo, a distinguished professor at Kyoto University who shared the 2018 Nobel Prize in Medicine or Physiology, said on a television program that Japan needs to ramp up PCR tests to detect virus infections to more than 10,000 per day, compared with the current peak of about 7,000 in mid-April -- dividing cases up into people with serious, mild and no symptoms.
As part of his emergency proposals, he also urged residents of the three cities of Tokyo, Osaka and Nagoya to impose "complete self-restraint from outings" for one month.
"This is a fight against an invisible ninja. The battlefield is at home and abroad, and it is necessary to know where and to what degree the enemy exists around us," Honjo said.
Fukushima, a representative of the Japan Epidemiological Association based in Tokyo, said that predictions could be made about the effectiveness of practices such as handwashing and bowing instead of handshakes and hugs, since "the virus when attached to fingers can use the mucous membranes of the eyes, mouth and nose as portals of entry for potential infection."
Masks, she stresses, are believed to control infection transmissions by reducing the dispersion of droplets discharged from the mouths of infected persons.
She noted that a preliminary study published in early March in the Japan Medical Association on the dispersal of viral traces at an outbreak center in Singapore found positive samples of COVID-19 from a symptomatic patient beyond just personal protective equipment of medical staff.
"The virus was detected from the floor of the patient's room, and for PPE the front surface of shoes. That does not immediately suggest a harmful effect from outdoor shoes, but it also suggests that we cannot rule out the virus clinging to shoes and being transported by them, either," Fukushima said.
Santarpia also found viral contamination in air samples, surfaces such as toilets and other surfaces that are frequently touched in a preliminary report published in late March, which has not yet been peer-reviewed, on the database medRxiv. He will likely start looking at viral contamination of clothing and shoes of health care workers soon, he says.
But he said it was too early to make a correlation between the rate of COVID-19 cases and various hygiene practices across cultures slowing the progression of the disease.
"Overall, I think we will have to wait until this is over to be able to truly see how the pandemic impacts different countries and cultures, but those countries who already practice many rules that some countries are slow to accept, may have an advantage," he said.
A new study by the Centers for Disease Control and Prevention found that about half of health care professionals working in intensive care units carried the coronavirus on the soles of their shoes at a hospital in Wuhan, China, where the outbreak started.
Asked about the effectiveness of Japan's practice of removing shoes before entering the home in protecting against COVID-19, Roess, an expert on global zoonotic infectious diseases, said infection from shoes of SARS-Cov-2, the virus that causes COVID-19, is unlikely, but an abundance of caution is still warranted.
"There is evidence that having a no-shoes-in-the-house policy can reduce the risk of pathogens that cause diarrhea, and this is especially important if you have infants or young children who are crawling and putting things in their mouths," she added.
Aside from homes, schools in Japan require students to remove their shoes, which are placed in a shoe rack called a getabako, all the way through high school.
Most temples, shrines, traditional inns, and hot springs resorts require you to remove your shoes -- all in the name of cleanliness. Some restaurants, which also provide cubbyholes, ask patrons to take shoes off. And clothing stores will often request that you remove them before entering a changing booth.
Fearing an explosion of cases, the Japanese government has declared a nationwide state of emergency to curb the spread of the new coronavirus after an alarming growth in cases in urban areas, including Tokyo and Osaka, urging residents to refrain from nonessential outings and some businesses to shut.
Social distancing, however, has been lax in comparison to the strict guidelines being followed in other countries, with not much evidence of people observing the 2-meters-apart distancing goal set by Tokyo's governor, Yuriko Koike, who has asked residents to refrain from being in enclosed spaces, crowded places or in close contact with each other.
Plastic curtains have been installed at many convenience store checkout counters to prevent infections between customers and store employees.
And while schools have closed and universities, cinemas, live music venues, nightclubs, pachinko parlors and internet cafes have been asked to suspend operations in the capital and elsewhere under the state of emergency, Tokyo's restaurants and Japanese-style "izakaya" pubs are still operating, although they have been requested to shut by 8 p.m.
"There is probably still this feeling of 'As long as I have my mask I'll be fine," said Fukushima. "But with the declaration of a nationwide state of emergency (on April 16), people here probably will not be in a situation where they can continue saying this."
Scientists are still grappling with many unanswered questions about how the disease can spread, including through people who show little or no symptoms in what might be aerosol transmissions -- fine particles that can stay suspended in the air for hours -- and surface contact transmissions.
What will be the takeaways learned from various cultures in a world utterly transformed by the COVID-19 pandemic?
Life in the United States could also be radically different with social distancing measures enduring until 2022, including waiters using face masks and gloves and throwaway menus, until a vaccine is found, according to researchers at the Harvard School of Public Health. But will it become more like Japan?
"There is evidence that wearing masks, good hand hygiene, and practicing social distancing are the best ways to halt the spread of the virus. Cultural norms in Japan include some of these and time will tell if those are, in fact, why Japan has lower COVID-19 infection and death rates than other countries," Roess said.