Nippon Professional Baseball and soccer's J-League should consider playing games without fans, a panel of experts recommended to Japan's biggest pro sports bodies when they met Friday for their eighth online summit regarding the coronavirus pandemic.

In the online press conference that followed, Mitsuo Kaku, a professor at Tohoku Medical and Pharmaceutical University, spelled out some key points the leagues should consider to prevent games from becoming viral hotspots.

These included minimizing team travel and the way they move around, and infection countermeasures in stadiums to ensure the safety of staff and fans.

"To be honest, our sincere recommendation is that teams only start playing behind closed doors," said Kaku, who specializes in infection control and prevention.

"They can work out step-by-step guidelines going forward to prevent their games from becoming clusters. The state of emergency has been lifted in most of Japan and could be lifted in the capital by the end of this month, but we still have to be careful. A second wave of infections is a possibility and we don't want to contribute to another surge."

NPB Commissioner Atsushi Saito said the sports bodies had already received an 80-page document with recommendations from a panel of public health specialists, and that all 12 NPB teams had also received a copy.

"We have been making plans to start the season," he said. "But we want to consider the guidance of the doctors in every step we take going forward."

When fans do make it to games, as in Taiwan's pro baseball league, Kaku said measures should be taken to limit the amount of time they eat and drink in their seats, when their masks will not be securely fastened.

He added travel poses problems, because it involves interaction with the public.

"It's one thing for a group of people, such as a sports team, who are under strict controls, but travel means that group will come into contact with people who aren't," Kaku said. "And there are still people who aren't wearing masks."

This year's NPB season was scheduled to start on March 20 before infections spiked across Japan, and a state of emergency was declared in April due to the spread of coronavirus.

The J-League was suspended in February, after the first round of matches in the first and second divisions.

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