Scan the website of any school that has reopened in the Covid-19 era, and you’ll find a litany of “enhanced disinfection protocols.”
Cleaning schedules for whiteboards, light switches, and cafeteria microwaves. Lists of government-approved carpet disinfectants. An accounting of “hypochlorous acid disinfectant wipes” in staff restrooms.
Keep clicking and you’ll find the school’s “physical distancing framework” — protocols for university shuttles and chemistry labs, guidelines for classroom desk dividers and elevator occupancy.
As schools welcome students and teachers back to class, they are seeking to inspire confidence in their Covid-19 precautions. But just how effective are all these measures?
It’s a high-stakes question. Already, more than 50,000 coronavirus cases have been reported by U.S. colleges, U.S. pediatric cases have hit half a million, and outbreaks have forced schools worldwide — from Wales to Israel to the United States — to close just days after re-opening.
In Berlin, Germany, coronavirus cases were reported by at least 41 schools a fortnight after the capital’s 825 schools reopened.
As for the answer: Scientists say schools are largely missing the boat.
“Surfaces are not really the problem,” asserts microbiologist Emanuel Goldman, Ph.D., of Rutgers New Jersey Medical School. “What [schools] really should be doing is focusing on the main routes of transmission of this disease, which is breathing.”
That’s why physical distancing measures indoors are of limited value, too.
"Distance alone will never solve the aerosol problem,” says Jose-Luis Jimenez, Ph.D., a University of Colorado chemist. “If you are in the same room, you can get infected.”
It’s well documented that coronavirus particles can linger in the air and travel across a room. To protect students and staff from inhaling these particles, schools must focus less on disinfecting desks and more on disinfecting the air.
Of course, SARS-CoV-2, the virus that causes Covid-19, isn’t the only pathogen swirling about campuses. School buildings are reservoirs for a range of airborne viruses and bacteria, as well as asthma-inducing mould spores and pollutants such as volatile organic compounds (VOCs). The coronavirus pandemic has only underscored the need for schools to deploy air-disinfection technologies year-round.
“They’re not only going to be helpful for Covid-19 but for next year’s flu season,” says David Brenner, Ph.D., a Columbia University physicist.
And not just to minimize influenza spread but also to quell the inevitable outbreaks of norovirus, common cold, and even high infectious diseases such as measles, now making a comeback around the world. As one American epidemiologist noted, once the Covid pandemic fades, schools will continue to have “the massive responsibility to safeguard the health and well-being of their students.”
Why Surface Cleaning and the 2-Metre Rule Fall Short
Scientists agree surface cleaning plays a minor role, at best, in controlling transmission of SARS-CoV-2. In fact, elaborate disinfection measures have been dubbed “hygiene theatre,” a feel-good display of concern that provides little actual protection.
School surface protocols emerged after early research suggested SARS-CoV-2 can survive for days on metal and cardboard. But recent analyses found those studies used exaggerated conditions. As Columbia’s Dr Goldman notes, up to 100 people would need to sneeze in precisely the same spot to match some of the experimental conditions.
The early studies, Goldman argues, “stacked the deck to get a result that bears no resemblance to the real world.”
What is happening in the real world: aerosol transmission, often by young people with no symptoms. A student who feels top-notch can, merely by asking a question, emit infectious particles light enough to sail across a classroom, even a lecture hall. A single minute of loud talking could launch over 1,000 virus-containing droplets.
Depending on the conditions, SARS-CoV-2 can travel well beyond 2 metres, the default distancing guidance for schools. In one hospital study, scientists captured viable airborne coronavirus particles nearly 4.8 metres away from a hospitalized Covid patient.
The guidance dates from 19th-century research suggesting 6 feet (approximately 2 metres) was as far as microbe-laden droplets could travel. Today’s more sophisticated studies, using laser-light technology, demonstrate that droplets exist in a range of sizes, cluster in invisible clouds, and can travel much farther indoors.
Six feet is a fine number, but we need to convey that this is a starting point,” says Linsey Marr, Ph.D., a Virginia Tech environmental engineer.
Case reports bolster the evidence. For example, in a well-known Washington choir practice, one singer spread SARS-CoV-2 as far as 13.5 metres; 53 of 61 choir members became infected, and two died.
No doubt infectious particles can waft about classrooms, hallways, staff lounges — anywhere on campus, including restrooms.
“When you flush a toilet, the churning and bubbling of water aerosolizes faecal matter,” explains Joseph Allen, Ph.D., director of the Healthy Buildings program at Harvard’s school of public health. “You’re breathing in toilet water and whatever is in that toilet water — including viruses and bacteria.”
SARS-CoV-2 may well be among those viruses.
In hospital studies, traces of coronavirus RNA have been detected in air samples collected near toilets of Covid-19 patients. Bioaerosols may linger for more than 30 minutes after a flush, other research has found. What’s more, compared to toilets with lids, lidless toilets — standard in elementary and secondary schools — increase the risk infectious particles will escape.
Enforcing the 2-metre rule won’t lower the odds that a student or staff member might inhale those particles. Neither will scrupulous disinfection of door handles and microwaves.
All in all, experts concur, school Covid precautions are falling short. Indeed, one American epidemiologist called the priorities at her own child’s school — one-way hallways, frequent sanitizing, temperature checks — “dangerously misdirected.” Airborne coronavirus spread, she lamented, was “absent from the conversation.”
Read part two here.