How Japan's slow acknowledgement of
COVID's airborne spread has
hampered its response
It was thought to be the end of a monthslong COVID-19 controversy in Japan.
The National Institute of Infectious Diseases announced its determination latelast month that the coronavirus spreads when one inhales virus-laden aerosols,
or tiny particles mixed with water floating in the air for an extended period oftime, confirming a view long held by much of the scientific community.
The NIID’s March 28 statement said the virus is mainly transmitted three ways:
breathing in virus-containing aerosols traveling over long distances; having
relatively large droplets land on the mouth, nose or eyes through a sneeze orcough; and touching the eyes, nose or mouth with virus-infected hands.
Previous reports issued by the health ministry-affiliated institute ruled out thepossibility of aerosol transmission and referred only to the other two.
But for many health experts in Japan, the revision didn’t go far enough andfailed to outline how this should affect antivirus measures.
The health ministry is still sticking to the idea that there is a “clear distinction”
between “aerosol transmission” and “airborne transmission,” denying thepossibility that the coronavirus can spread through the latter.
The difference between the two, as explained by a health ministry official last
week, is that aerosol transmission contains water but airborne transmission
does not. “Airborne transmission occurs in measles and tuberculosis, forexample,” the official said. “We do not think, at this point, that the coronavirus
spreads through airborne transmission.”
The reluctance to admit that the coronavirus is airborne — in contrast with theWorld Health Organization — as well as the slow acknowledgment of aerosol
transmission, has marred Japan’s response to the pandemic by making indoor
air safety seem less essential, some experts say. Experts counter thegovernment’s view that Japan has stressed the importance of ventilation by
urging the public to avoid closed spaces, saying that the lack of clear guidanceon aerosol and airborne transmission has led to confusion. The experts argue

that has put elderly people in nursing homes and front-line care workers
particularly at risk of “cluster” infections.
Not only that, this attitude might have led to excessive regulatory emphasis on
surface cleaning and plastic partitions as preventive measures, when in fact
infections via close-range droplets and contact may be rarer than once thought.
Over the course of the two-year-old pandemic, the international scientificcommunity has come to a broad consensus that the coronavirus is airborne. InDecember, more than a year after some scientists flagged that the virus may beairborne, the WHO updated its website entry on how COVID-19 is spread. It
now refers to “aerosol transmission” and “airborne transmission” synonymously
and says this is a primary way the disease is passed on to others.
To take basic antivirus precautions, such as properly ventilating restaurants andhomes, people need to know how the virus spreads, says Tsuyoshi Hondou, anassociate professor of theoretical physics at Tohoku University. | BLOOMBERG
Tsuyoshi Hondou, an associate professor of theoretical physics at Tohoku
University who has promoted efforts to have Japanese authorities acknowledge
aerosols as a vehicle of COVID-19’s spread, hailed the NIID’s March 28
announcement, saying it’s a “step in the right direction.” But he says theinstitute and the health ministry should be more vocal in addressing the risks of— and tools to fight — the virus-laden aerosols.
In August 2021, at the height of the fifth wave of infections amid the spread ofthe delta variant, Hondou and 37 other scientists from across the nation
released an urgent message calling for measures “based on the latest scientificfindings” on airborne transmission.
The scientists, in particular, pushed for the use of tight-fitting, single-use
nonwoven fabric masks and mechanical ventilation systems, such as air filtersand heat exchangers, given that the scorching summer heat at that time made itdifficult for people to open their windows and doors to let fresh air in.
Then in February, Hondou and nine others sent an open letter to NIID director
Takaji Wakita, questioning a report by the institute issued the previous monththat said the main transmission routes for the omicron variant were throughcontact and droplet transmissions. The group said the institute’s omission ofaerosols “contradicted the global consensus.”

“(Government officials) say we should take all kinds of measures,” Hondou said.
“But we are all busy and have limits in our budgets and time. That’s why wemust have information on which of the three is the most important. They are
not providing that information.”
To take basic precautions such as wearing tightly fitted nonwoven fabric masks
and constantly ventilating restaurants and homes, people need to know how thevirus spreads, he said.
“Why are (restaurant staff) wiping a chair every time somebody leaves? People
also need to know why they need to have their masks fit tightly with no space.”
A reluctance to admit that the coronavirus is airborne — in contrast with theWorld Health Organization — as well as the slow acknowledgment of aerosol
transmission, has marred Japan’s response to the pandemic by making indoor
air safety seem less essential, some experts say. | BLOOMBERG
The health ministry, for its part, says they have always stressed the need forgood ventilation. And there’s some truth to that — Japan prides itself on
advocating from early in the pandemic the importance of avoiding the three Cs:
crowded places, close-contact settings and closed spaces. Avoiding closed spaces
has also come with a call for rooms to be well-ventilated.
But Hideki Yamazaki, a psychiatrist and director of Seizankai, a medical
corporation based in Miyagi Prefecture that operates 50 nursing homes andother facilities mostly for elderly people with dementia, says measures against
aerosols aren’t mandated on the ground, saying many care workers are notaware of the danger of infectious viral particles in the air.
So far, Yamazaki’s group has reported 18 COVID-19 cases among patients andstaff, but no “cluster” infections, which refers to an outbreak of more than fivepeople in the same area at the same time. In addition to in-house PCR testing
and a system that supports staff when they become infected or become close
contacts, the group has mandated proper ventilation and the use of N95 masks
among staff working in the “red zone,” where infected patients are cared for.
At care facilities in general, however, N95 masks are probably used less thanhalf the time, he said. At other facilities where his staff have been dispatched as
emergency helpers, red-zone workers in protective gowns and face shields werescrambling to disinfect their hands and the floors while their surgical masks
were loosely fitted, he noted.
“Workers at care facilities and restaurants would understand the importance ofventilation far better if they are told the virus is airborne, rather than having theminute differences between droplets, droplet nuclei, microscopic droplets andaerosols explained to them,” Yamazaki said, citing the explanation on particles
of different sizes currently provided by the ministry.
While it’s unclear why Japan is reluctant to admit the virus is airborne, Hondou
speculated that public health officials — mostly comprised of licensed medical
doctors — may have a hard time breaking away from the traditional mindset
they adopted from medical textbooks that airborne transmission typicallyoccurs in diseases that are far more infectious than the coronavirus, such as
measles, tuberculosis and chicken pox.
There are also dissenting views among scientists on how often airborne COVID19 transmission takes place. Academics also seem divided on the exact
definition of aerosol transmission.
Differing views aside, government guidelines for facilities caring for the elderly,
who are most vulnerable, should be urgently updated, reflecting the best scienceavailable so far, Yamazaki said.
Yamazaki pointed to a recent feature in the journal Nature that probed why theWHO itself took two years to say the coronavirus is airborne, citing a quote froma historian and public policy expert who said that the organization failed in two
respects: “Being reluctant to change your mind, and being reluctant to tellpeople you changed your mind.”“The health ministry is committing a sin of omission by explaining that aerosol
transmission is different from airborne transmission,” Yamazaki said. “To me, itruns parallel to the failures of the WHO.”