The rate of coronavirus infections in China continued to drop Thursday, but flare-ups elsewhere turned a thriving South Korean city into a ghost town and Japan said two elderly passengers of the Diamond Princess cruise ship died as a result of their infections, raising fears about the bug’s global reach.

Daegu, a city in southeastern South Korea, recorded dozens of new cases in recent days, prompting its 2.5 million residents to clear out of normally busy streets and shopping malls.

Fearing the spread of the virus among its armed forces, South Korea also restricted military personnel from taking leave, staying off base overnight or greeting visitors at their installations.

The global creep of the illness known as COVID-19 prompted the World Health Organization to issue a warning: Act now or face an even bigger crisis down the road.

“Let’s not squander the window of opportunity we have,” WHO Director-General Tedros Ghebreyesus said. “The number of cases in the rest of the world is very small compared to what we have in China, but that may not stay the same for long.”

The coronavirus has disrupted global supply chains and travel plans and upended daily life in parts of Asia, particularly at the epicenter of the outbreak in Wuhan, a large city in China’s Hubei province.

Some scientists say the new coronavirus might be here to stay so mitigation will be key.