Japan once appeared to be avoiding a full-blown epidemic, but the country has recently seen a large increase in coronavirus cases.

Former Prime Minister Yukio Hatoyama said the Japanese government failed to adequately address the viral outbreak, putting the now-cancelled 2020 Olympics above the health of citizens.

In Tokyo, two viral clusters were discovered Sunday. They could be a sign that the outbreak will soon worsen.

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Earlier this month, Japan appeared to have the novel coronavirus epidemic well-contained. According to data from Johns Hopkins University, the country reported zero cases of COVID-19, the disease caused by the virus, on March 11 and again less than a week later, on March 15.

But by March 24, when Tokyo called off the 2020 Olympics, the virus was spreading rapidly.

In Tokyo alone, Monday marked the biggest daily increase in COVID-19 cases since the epidemic began: 68 people tested positive on Sunday, March 29, according to Reuters, which cited local media. In total there have been 1,866 confirmed cases across Japan.

Concerns about containment, and COVID-19 clusters, are surfacing

Just three days after Japanese Prime Minister Shinzo Abe decided to delay this year’s Olympics, Japan saw its biggest daily increase as a country: at least 225 cases emerged March 27, according to Johns Hopkins data.

Some concerns have emerged about the country’s containment measures, and there is speculation that mitigation strategies were delayed in order to quell fears about hosting the Olympics during an outbreak.

“In order to make an impression that the city was taking control of the coronavirus, Tokyo avoided making strict requests and made the number of patients look smaller,” tweeted former Prime Minister Yukio Hatoyama, whose administration Abe once called “a nightmare“.

“The coronavirus has spread while they waited,” Hatoyama added. “[For Tokyo Gov. Yuriko Koike] it was Olympics first, not Tokyo’s residents.”

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A day after the Olympics was postponed, Gov. Koike said Tokyo residents should stay home on weekends until at least mid-April, Japan Times reported. “To avoid an overshoot in infections, the cooperation of Tokyo residents is critical. I ask you to act with a sense of crisis,” she said.

Tokyo’s residents may face an increased risk of infection: at least two viral clusters have recently emerged, according to local broadcaster NHK.

More than 20 cases were confirmed in a hospital in Taito, an eastern Tokyo ward that has already seen many staff and patient infections.

Another cluster was reported in a home for people with disabilities in Chiba prefecture, near Tokyo. Sunday saw 28 confirmed cases there.

Japan is currently only testing people with symptoms, and those connected to clusters. As in the US, the stringent testing requirements reflect officials’ concern that widespread testing would overwhelm the healthcare system.

But the clusters signal that the outbreak could worsen in the immediate future.

“Once infections overshoot, our strategy … will instantly fall apart,” Abe said, adding that Japan’s health crisis could soon be comparable to the US or Europe’s. “Under the current situation, we are just barely holding up.”

Last week Abe convened a task force to consider declaring a state of emergency. People should “be prepared for a long battle,” he said.