Time For Some Sober Second Thought

 

A recent poll shows that about half of all Canadians are ignoring the Covid guidelines telling people to socialize only with those in their own household:

A new survey suggests nearly half of Canadians visited with family or friends over the winter holiday period.

The Leger/Association for Canadian Studies poll found 48 per cent of those surveyed visited with people outside their households, compared to 52 per cent who said they did not.

Public health officials had pleaded with Canadians to sharply limit their contacts during the holidays to avoid massive spikes in COVID-19 cases.

But it appears something gave for Canadians, said Leger vice-president Christian Bourque.

“Usually we Canadians are sort of much more, I would say, disciplined when it comes to going by what governments are recommending in terms of our behaviour, but over the holidays, apparently, it was sort of tougher on Canadians,” he said.

A study from Korea suggests that it is more than time that such people give a sober second thought to their recklessness. It is a story that suggests the easy transmissibility of the virus and calls into question whether the two-meter social distancing guidance is adequate

Dr. Lee Ju-hyung has largely avoided restaurants in recent months, but on the few occasions he’s dined out, he’s developed a strange, if sensible, habit: whipping out a small anemometer to check the airflow.

It’s a precaution he has been taking since a June experiment when he and colleagues re-created the conditions at a restaurant in Jeonju, a city in the southwest of South Korea, where diners contracted coronavirus from an out-of-town visitor. Among them was a high school student who was infected with the coronavirus after five minutes of exposure from more than 20 feet away.

It appears the culprits here are being indoors with others and airflow.

Linsey Marr, a civil and environmental engineering professor at Virginia Tech who studies the transmission of viruses in the air, said the five-minute window in which the student, identified in the study as “A,” was infected was notable because the droplet was large enough to carry a viral load, but small enough to travel 20 feet through the air.“‘A’ had to get a large dose in just five minutes, provided by larger aerosols probably about 50 microns,” she said. “Large aerosols or small droplets overlapping in that gray area can transmit disease further than one or two meters [3.3 to 6.6 feet] if you have strong airflow.”

Lee, a professor at the Jeonbuk National University Medical School who has also been helping local authorities carry out epidemiological investigations, went to the restaurant and was surprised by how far the two had been sitting. CCTV footage showed the two never spoke, or touched any surfaces in common — door handles, cups or cutlery. From the sway of a light fixture, he could tell the air conditioning unit in the ceiling was on at the time.

Lee and his team recreated the conditions in the restaurant — researchers sat at tables as stand-ins — and measured the airflow. The high school student and a third diner who was infected had been sitting directly along the flow of air from an air conditioner; other diners who had their back to the airflow were not infected. Through genome sequencing, the team confirmed the three patients’ virus genomic types matched.

Clearly, there is still much to be learned about Covid-19. Those who think they know it all and conduct themselves blithely may not live to regret it.