TOKYO — In Japan, one cold remedy promotes itself as quick and effective — "even when time off is not an option."

In the time of coronavirus, the advertisement has come to symbolize the challenge for Japan as collective health advice smacks into a work culture built on muscling through at any cost.

Japan’s government has advised people to stay home if they develop a fever or flu-like symptoms, but while schools have been shut across the country, workplaces have largely stayed open for business as usual.

The government’s guidance clashes with deep-rooted traditions about obligations in the workplace. Japan even has its own word for death by overwork, “karoshi.” A sick day is often frowned upon and usually counts toward an employee’s vacation entitlement.

There are plenty of other places — including the United States — where employees feel an unspoken pressure to show up even if they don’t feel well, or face a paycheck hit if they call in sick.

Roughly 25 percent of American workers have no paid sick leave, leaving many with little choice but to go into work while ill.

But it is often more extreme in East Asia’s fiercely competitive and workaholic societies. For health officials in Japan and South Korea, it’s a battle against both the virus that causes covid-19 and entrenched views on work.

“Japan has a work culture where covid-19 would be more prevalent compared to other countries,” said Kenji Shibuya, director of the Institute for Population Health at King’s College, London.

So it’s hardly surprising that media reports are already emerging of Japanese men and women who carried on working even after they developed symptoms, and passed on coronavirus to their colleagues or customers.

There’s the male surgeon in Wakayama who developed a fever at the end of January, but kept seeing patients for three days while taking medicine to lower his temperature before finally developing pneumonia-like symptoms. At least four other people at the surgeon’s hospital also caught the virus, including another doctor, who also kept seeing patients for days after developing a cough and a fever.

There’s the businessman who took a Shinkansen bullet train on a business trip after coming down with a fever, and the lunch lady at an elementary school who continued to deliver food to classrooms even after developing a sore throat. Both were later found to have covid-19.

“In some workplaces, people are expected to come into work even if they are sick,” said Rochelle Kopp of Japan Intercultural Consulting, a training and consulting firm focusing on Japanese business.

“In other cases,” she added, “nobody may be telling them they have to come in when they are sick, but they do so anyway due to a sense of responsibility, a desire not to use vacation days or general macho-ness.”

In South Korea, it’s a similar story. Put simply, experts say, there is no point in canceling public events and gatherings and closing schools if sick people continue to commute in packed subway trains and show up at work.

“South Korea’s corporate culture — that deems working while sick a virtue — pushes ill employees to show up at the office,” said Choi Eun-hwa, professor of pediatrics at Seoul National University College of Medicine. “This absolutely needs to change under the current epidemic.”

Choi was a member of a panel of medical experts who met South Korean President Moon Jae-in last month and told him employees should be allowed to take paid sick leave or work from home to prevent the virus spreading.

In Japan, the government has encouraged companies to allow “telework” or stagger working hours so Tokyo’s packed subways are not quite so crowded during the epidemic.

In South Korea, Seoul’s mayor, Park Won-soon, called on Monday for a two-week “moment of pause” to contain the spread of the coronavirus.

Some companies are listening.

South Korean mobile carrier SK Telecom told its 5,400 employees to work from home, but electronics giants Samsung and LG say only pregnant women or employees whose children’s schools or day-care centers have been closed because of the virus can work from home.

For some, it has taken an infection to force through the change.

At Dentsu, Japan’s largest advertising agency, 5,000 employees at its Tokyo head office were told to work from home after an employee contracted the virus. Telecom giant Nippon Telegraph and Telephone has also urged telework.

In recent days, Tokyo’s subway trains have not been quite as packed as before, but they are still busy, underlining the journey Japan has to travel as it adapts to the epidemic.

“Japanese practice is that people go to work,” said Hiroyuki Noda, a councilor at the Cabinet Secretariat responsible for measures against infectious diseases. “Whether that can be changed — well, that may be a challenging thing.”

Kim reported from Seoul.