As the coronavirus shows signs of starting a comeback in B.C. and Alberta and it rages out of control in the U.S., a fundamental question remains confusing for some: “How is the virus spread and what can be done to stop it?”
It doesn’t help that especially in the early days, considerable misinformation and contradictory information was put out by organizations we rely on for answers – the World Health Organization (WHO), the U.S. Centers for Disease for Disease Control and Prevention (CDC) and the Public Health Agency of Canada (PHAC).
I don’t believe for one minute Donald Trump’s recent retweet from a game show host, Chuck Woolery, who claimed the CDC and others are “lying” to the American people.
Rather, I think it’s because of the tendency of bureaucracies to resist new information and for generals to fight the last war. Many of the earlier incorrect statements about Covid-19 were based on the experiences with SARS and MERS, without understanding how the novel coronavirus is different.
At the same time, however, a large amount of information about Covid-19 is being discovered by scientists conducting research in the field, or by medical professionals observing real patients. Often their discoveries are posted on “preprint” websites before it can be peer reviewed. Such preprint papers need to be viewed with caution, but when numerous scientists make the same discoveries, it’s worth paying attention.
Twice recently the WHO has been taken to task by researchers who believe WHO’s information was misleading at best – the claims that the virus is not “airborne”and that asymptomatic transmission of the coronavirus is “rare” Both these claims involve semantics, but the result is the public is left confused.
The dictionary definition of airborne is simply “transported by air.” Coronavirus is mostly transported by air, whether from coughing, sneezing or “speaking moistly” as Prime Minister Justin Trudeau eloquently put it.
Medical professionals, however, use the word “airborne” in a stricter sense to mean pathogens that are so small they remain in the air for a longer period of time. An example is measles, which can remain contagious in the air for up to two hours. This is in contrast to larger respiratory droplets that fall to the ground much sooner.
While the coronavirus probably doesn’t linger as long in the air as measles, there is growing evidence that it does linger in the air and that it can spread in aerosol form – not only during medical procedures like intubation, but when groups of people gather indoors, for example to sing in a choir.
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- See “Mounting evidence suggests coronavirus is airborne – but health advice has not caught up” – Nature
- See “239 experts with one big claim: the coronavirus is airborne” – New York Times
Only on July 9 did WHO finally publish a brief acknowledging that airborne transmission likely takes place.
The flip side of this miscommunication is the widespread belief that coronavirus is primarily spread by contaminated surfaces.
All of us have seen grocery store personnel carefully wiping down the conveyor belt at the checkout counter with disinfectant while not wearing a mask.
Playground equipment, quickly sterilized in the hot sun and probably safe, was closed off. Even park benches were viewed as Covid vectors. People wiped down their groceries or were afraid to exchange books. The fear of transmission by surfaces – fomite transmission – is vastly overstated, even though it’s possible.
WHO finally acknowledged this in its brief, noting that tests have shown the virus can survive for hours or even a few days on some surfaces, and fomite transmission may occur.
Nonetheless, WHO adds:
“Despite consistent evidence as to SARS-CoV-2 contamination of surfaces and the survival of the virus on certain surfaces, there are no specific reports which have directly demonstrated fomite transmission.” – WHO July 9 brief
So it’s probably still a very good idea to wash your hands or use sanitizer and not to touch your eyes, but if you’re going to get Covid, this is not the most likely way you’ll get it.
The claim that asymptomatic transmission of the virus is “rare” is also based on misleading semantics, but it’s a deadly claim to make – probably in hindsight this misinformation will be seen to have caused hundreds of thousands of deaths.
Once again, the dictionary definition of “asymptomatic” is clear – it means “without symptoms.” But agencies like the WHO have differentiated between “presymptomatic transmission” and “asymptomatic transmission.” The former means that people don’t show symptoms when they transmit the virus, but develop symptoms later. The latter means they never show symptoms.
But this semantic hair splitting misses the point. The fact that people are shedding the virus before they show symptoms is huge. Whether or not they go on to develop symptoms later is largely irrelevant to the fundamental question.
This is a basic difference from SARS, which generally was not transmitted asymptomatically. Most people won’t knowingly spread a disease if they think they’re infected, but if SARS-CoV-2 (the novel coronavirus) is spread by people who don’t know they’re sick, this makes it much more dangerous than the 2003 SARS outbreak.
Scientific research is now finding that somewhere between 30 and 50 percent of transmission occurs before people show symptoms, and people in the early stage of the disease are usually the most contagious.
But the misleading statements downplaying asymptomatic transmission have led to ineffective policy measures. We see warnings telling people not to enter businesses if they are showing symptoms. People in airports are screened with touchless thermometers for fevers, even though people without fevers can still be contagious. Covid tests in many jurisdictions, including B.C., are directed mainly at those showing symptoms.
Meanwhile, the focus only on people who are symptomatic means the virus spreads silently and undetected until it’s too late.
Another subject where health agencies have misled the public and done 180-degree turns is the use of masks.
A reasonable message in February and March would have been that N95 and surgical masks were in short supply and so should be conserved for health professionals and definitely should not be hoarded.
Instead, people were told that masks were vital for healthcare workers, but were actually harmful when used by asymptomatic members of the public. Even homemade cloth masks were said to be dangerous because the public could not be taught how to use them properly.
This message damaged the credibility of health agencies – especially as science was showing masks do provide some protection and grassroots organizations sprang up to make and distribute cloth masks. Some countries like Czechia started mandating masks.
Only in early April did CDC finally do an abrupt flip-flop and acknowledge that maybe masks were a good idea after all. PHAC was even slower to give tepid support to masks.
Then masks became politicized in the U.S. where wearing one was seen as a sign of disloyalty to President Trump.
It’s tempting at this point to throw up our hands and say that public health agencies can’t be trusted, or even go so far as Trump’s game show host friend and say they’re “lying.” But that would be a serious mistake. They’ve made huge missteps, but that is the result of the newness of the virus and the nature of bureaucratic decision making.
Rather, we should revisit the fundamental question posed at the beginning of this article in light of new information: “How is the virus spread and what can be done to stop it?”
1. It’s mainly spread through the air, whether you use the term “airborne” or not. It can be spread directly by respiratory droplets, or as an aerosol that can linger in the air in some situations.
2. Surface (fomite) transmission is possible, especially if you don’t wash your hands and stick your fingers in your eyes or up your nose. But its importance is exaggerated. Frankly, if given only one choice, I would rather see store employees wear masks than be constantly wiping down counters.
3. You can’t tell if someone is contagious by whether or not they show symptoms because asymptomatic (or “presymptomatic” if you prefer) transmission is common. It’s best to assume others outside your family could be infected, whether or not they are coughing and sneezing.
The best advice continues to be:
1. Stay at least two metres distance from others and ideally more. Physical distancing is one of the most important things you can do, but for some reason it’s been one of the hardest.
2. Outdoor air is safer than indoor air. In particular, avoid large crowds indoors, especially if they are singing or yelling.
3. Wear a mask, especially in indoor situations and where you can’t maintain a two-metre distance.
4. Wash or sanitize your hands and don’t touch your face, but don’t get so caught up in fears of surface transmission that you neglect 1, 2 and 3.
