TOKYO — My Home Harumi, a nursing home in central Tokyo, is on lockdown.

Volunteers, service providers and even family members are turned away in hopes of keeping the center sealed against the spreading coronavirus. A sense of crisis pervades the home as employees wear masks, constantly wash their hands and disinfect every surface, said its deputy director, Kumi Iwasaki.

It’s a life-or-death mission: The virus kills older people at a far higher rate. The battle is being waged all across Japan, which has the highest proportion of elderly people in the world, as the number of reported cases in the country has steadily climbed to 230, with 11 deaths, mostly among people in their 80s. Globally, nearly 3,000 people have died, the vast majority in China.

Other countries with aging populations, like South Korea and Italy, which have both experienced recent surges in infections, are also facing acute challenges. Those two countries have done just what experts recommend: They have moved quickly to test large numbers of people so they can be treated and isolated from others.

But after weeks of caution, the Japanese government has only just begun to take more aggressive action, most notably by moving to close schools for a month. That step, though, was aimed at the young, who often show only mild symptoms or none at all when infected, not vulnerable older people, who sometimes develop severe pneumonia.