Japan disease institute says aerosol transmission could lead to COVID infection
TOKYO -- Japan's National Institute of Infectious Diseases (NIID) announced on its website on March 28 that the coronavirus can be transmitted through inhalation of aerosols floating in the air containing the virus.
The NIID had previously published a report that said aerosol infection was not possible and listed only droplet and contact transmission as infection routes. Domestic scientists then submitted an open letter of inquiry demanding an explanation, saying that the report was different from other findings around the world.
In spring 2021, the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention stated that aerosol and droplet infections were the main routes of infection, and that contact infection was unlikely to occur.
However, in its report on the omicron variant released on Jan. 13 this year, the NIID gave a different explanation from the WHO and other organizations, stating, "at present we have not been able to confirm a clear rise in rates of cases suspected to be caused by aerosol transmission, and infection routes are mainly thought to be droplet infections and contact transmissions seen up until now."
In a document released on March 28, the NIID introduced three main routes of infection: aerosol, droplets, and contact. It then goes on to say, "Particles are released when an infected person breathes, and the amount of those particles increases when the person shouts loudly or sings. The closer you are to an infected person (within about 1 to 2 meters), the more likely you are to be infected, and the farther away (about 1 to 2 meters or more), the less likely you are to be infected."
Associate professor Tsuyoshi Hondo of Tohoku University, who compiled the open letter, praised the fact that aerosol infection was stated as a possible infection route, but pointed out, "Effective countermeasures will not spread unless the public is clearly informed that contact infection is said to be rare in the world."
Nobuaki Shimizu of Aichi Prefectural University also stressed, "It's important to clearly inform people that areas can become contaminated with aerosols containing viruses and therefore need to be ventilated."
(Japanese original by Naomi Hayashi, Lifestyle and Medical News Department)