Its lead researcher, Makoto Tsubokura, said that opening windows on commuter trains could increase the ventilation by two to three times, lowering the concentration of ambient microbes.
But to achieve adequate ventilation, there needed to be spaces between passengers, the simulations showed, representing a drastic change from Japan’s notoriously packed commuter trains.
Other findings advised the installation of partitions in offices and classrooms, while in hospitals, beds should be surrounded by curtains that touch the ceiling.
As Japan tamed the pandemic, with more than 19,000 confirmed cases and 977 deaths so far, Economy Minister Yasutoshi Nishimura credited its success to the 3Cs and its cluster-tracing strategy.
“In Japan, the committee for COVID-19 countermeasures insisted on the 3Cs at an early stage,” said Tanabe, a professor at Waseda University in Tokyo, referring to Japan’s public campaign to avoid “closed spaces, crowded places and close-contact settings”. “This is ahead of the world.”
Even if the coronavirus is airborne, questions remain about how many infections occur through that route. How concentrated the virus is in the air may also decide contagion risks, said Kyoto University professor Yuki Furuse.
The WHO has previously said the virus that causes the COVID-19 respiratory disease spreads primarily through small droplets expelled from the nose and mouth of an infected person that quickly sink to the ground.
Because those smaller exhaled particles can linger in the air, the scientists in the group had been urging WHO to update its guidance.
“We wanted them to acknowledge the evidence,” said Jose Jimenez, a chemist at the University of Colorado who signed the pen letter.
“This is definitely not an attack on the WHO. It’s a scientific debate, but we felt we needed to go public because they were refusing to hear the evidence after many conversations with them,” he said in an interview.
Speaking at a daily briefing in Geneva, Benedetta Allegranzi, WHO’s technical lead for infection prevention and control, said there was evidence emerging of airborne transmission of the coronavirus, but that it was not definitive.
“… The possibility of airborne transmission in public settings — especially in very specific conditions, crowded, closed, poorly ventilated settings that have been described, cannot be ruled out,” she said.
“However, the evidence needs to be gathered and interpreted, and we continue to support this.”
Jimenez said historically, there has been a fierce opposition in the medical profession to the notion of aerosol transmission, and the bar for proof has been set very high. A key concern has been a fear of panic.
The admission comes as US President Donald Trump’s administration sent a letter to the United Nations withdrawing the US from the WHO over its handling of the pandemic.
The notice of withdrawal was delivered to UN Secretary-General Antonio Guterres, a senior administration official said. Under the terms of a joint resolution passed by Congress in 1948, the US must give a year’s notice in writing and pay its debts to the agency in order to leave.
It is not clear whether the President can pull the US out of the organisation and withdraw funding without Congress approval. When Trump first threatened to withdraw, Democratic lawmakers argued that doing so would be illegal and vowed to push back.
“To call Trump’s response to COVID chaotic & incoherent doesn’t do it justice. This won’t protect American lives or interests – it leaves Americans sick & America alone,” Democratic Senator Robert Menendez tweeted.
Reuters, The Washington Post