A Japanese professor of infectious diseases said Monday that the Tokyo Olympic and Paralympic Games are not "likely to be held" in 2021, despite a one-year postponement, as the international community would not be able to weather the global coronavirus pandemic by then, unless the games are organized in a special format.

Kentaro Iwata, a professor of infectious diseases at Kobe University, said the games should be held only after the virus has been brought under control in Japan and elsewhere.

"Japan might be able to control this disease by next summer...but I don't think that would happen everywhere on earth," Iwata said in an online press conference arranged by the Foreign Correspondents' Club of Japan.

"I'm very pessimistic...unless you hold the Olympic Games in total different structures, such as no audience or a very limited participation," he said.

He criticized the Japanese government's handling of the rapid spread of the virus in the country in recent weeks, saying it is "so slow and so late in coping with the change of the situation."

The major reason, he believes, is the lack of information being shared by the authorities, including politicians and government officials.

Iwata, who joined a medical team sent to the Diamond Princess cruise ship that was quarantined near Tokyo in February, said their coordination has been "not coherent" and has resulted in "mingled" measures, making it difficult for them to deliver appropriate messages swiftly to people in the country.

Japan declared a nationwide state of emergency on Thursday, expanding the scope of regions being able to take stronger preventive measures based on a revised law through May 6 beyond Tokyo, Osaka and five other prefectures that had already requested citizens to stay at home and business owners to close shops.

While acknowledging that measures under the law for the state of emergency are not mandatory and carry no penalties, he stressed that authorities could have used the word "lockdown" and sent a more robust message to prevent people from leaving their homes and cities.

"The most effective way of stopping further transmission is a so-called lockdown," he said.

When Prime Minister Shinzo Abe declared a state of emergency for the seven prefectures, also including Chiba, Fukuoka, Hyogo, Kanagawa and Saitama, on April 7, he said that it does not mean imposing city-wide lockdowns similar to those in some other countries.

Iwata said Japan could see the end of the epidemic in several months if more effective measures are taken, but if not many more months will be needed.

Moreover, he said he "can't be really that optimistic" about potential vaccines, which may be developed in one or two years but their safety and efficacy will need to be proven by clinical trials and these will likely require more time.

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