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A stark warning shakes the economy

The World Health Organization said yesterday that coronavirus cases outside China were accelerating. Around 80,000 people in nearly 40 countries have been infected, and at least 2,600 have died.

Draconian measures in China have slowed the spread there, the W.H.O. noted, but the outbreak could prove hard to contain elsewhere. Most health experts are worried about Iran, Italy and South Korea. Japanese officials said today that the country, which has more than 800 confirmed cases, was at a “crossroads” in fighting the outbreak.

If other countries followed China’s “bold approach,” as the W.H.O. put it, widespread quarantines and other restrictions would hit the global economy hard. This fear was partially responsible for yesterday’s tumultuous markets, as investors hedged their portfolios, businesses revised their forecasts, and officials prepared for the worst.