Kentaro Iwata says that even if Japan can get the outbreak under control in time, there is no guarantee that other competing countries will be in a similar position.

The International Olympic Committee (IOC) confirmed the Games would be pushed back until 2021 because of the ongoing coronavirus pandemic.

It is the first time in history that the Olympics have been postponed during peacetime, with the Games in 1916, 1940 and 1944 canceled because of world wars.

"To be honest with you, I don't think the Olympics is likely be held next year, if held anytime," said the professor of infectious diseases at Kobe University.

"Japan might be able to control this disease by next summer, and I wish we could, but I don't think that would happen everywhere on Earth, so in this regard I'm very pessimistic about holding the Olympics Games in next summer."

IOC commits to safety

A number of medical experts have questioned the viability of staging the Games as normal if a vaccine isn't found in time.

Iwata suggests one option could be hosting the spectacle behind closed doors or totally changing the structure of competition, such as limiting the number of participants.

However, the IOC has not planned to change the format and says it will continue monitoring the situation amid pessimism from medical experts.

"We will follow the risk management and mitigation measures set out by the World Health Organization (WHO) for mass gatherings in the context of the current COVID-19 outbreak," read an IOC statement sent to CNN Sport.

"We will continue to follow the principle that has driven all our decisions so far, which is to organize Olympic Games only in a safe environment for all people involved. We are committed to following this principle in the future."

Continued spread

The virus has now infected more than 2.4 million people and killed at least 165,900 worldwide, with many governments responding by imposing strict lockdown measures.

Japan has more than 10,797 confirmed cases of Covid-19 with at least 236 deaths, according to the latest figures.

Iwata criticized the Japanese government for not acting quickly or efficiently enough to the initial outbreak in the country.

"Japan's government was so slow and so late in coping with the change of the situation which apparently is happening," he said.

"The most effective way of stopping the further transmission is a so-called lockdown, particularly in the Tokyo area."