Why Theresa Tam changed her stance on masks

Inderveer Mahal is a practicing physician in Vancouver. She completed a fellowship in global journalism at the Dalla Lana School of Public Health at the University of Toronto.

Wearing a mask was never a formal recommendation in Canada. But the science is shifting, and Canada’s top doctor is also changing her stance. Masking is now a definite tool in the fight against coronavirus, but Canadians are confused by the changes. Generally, widespread public health recommendations are based on rigorously analyzed evidence. But COVID-19 is a new virus and understanding exactly how it spreads and how to contain it is quickly changing. This Wednesday, when Theresa Tam announced the value of wearing a mask to prevent COVID-19, the new guidance caused confusion. For Tam, the evolving science of masks and shift of her recommendations have unfortunately raised questions about her competency,  leading to requests for her resignation.

We have to remember that coronavirus has only been circulating for the last six months. Our understanding of it during the early days of the pandemic was rudimentary. Public health recommendations were based off extrapolated data from older, better understood viruses like SARS and influenza. As our understanding of this new virus evolves, recommendations from the Public Health Agency of Canada and Tam, its most visible face, shift over time to reflect new developments. 

Masking has been one of the most contentious conversations throughout this pandemic. For our neighbours south of the border, wearing a mask or the absence of one, is increasingly becoming a political statement. Here at home, many Canadians have expressed confusion and disappointment that the Public Health Agency of Canada (PHAC) didn’t recommend widespread masking at the onset of the pandemic. But the effectiveness and need for wearing a mask to limit the spread of COVID-19 from asymptomatic people wasn’t clear in early March. So what has changed between now and then to make Tam and her team change their minds?

MORE: Why that about-face on wearing masks is a problem

The benefits of wearing a mask are seen primarily in health care settings, like hospitals or long-term care homes. According to peer-reviewed medical journal Nature Medicine, masks act as a method of “source control,” keeping infectious particles inside the mask and shielding others from potentially becoming infected. Yet the studies on masking tend to be smaller, underpowered and on the lower-end of the quality spectrum in terms research design. When it comes to stopping the spread of coronavirus, health authorities are confident in the effectiveness of isolation; isolating positive cases to stop further spread of the virus. And so for those with any symptoms suggestive of COV-19, the public health recommendations have remained clear and consistent: stay home and isolate yourself from others. 

The muddier question is whether a mask helps prevent the spread of coronavirus while healthy Canadians are out grocery shopping, biking or running. 

Infection control measures early in the pandemic were based off lessons learned from SARS in 2003, which was a fair approach because of the many commonalities between SARS and COVID-19. Both are coronaviruses, both showed evidence of being transmitted through respiratory droplets, and both viruses created pneumonia-like symptoms. Thus early public health measures were very similar to those used to combat SARS: find infected patients based on their symptoms, aggressively contact trace, test, isolate and quarantine their close contacts. But what differentiates COVID-19 from SARS is when it becomes infectious.

MORE: The history of our cultural resistance against masks

Unlike SARS, which had a low risk of transmission until five days after symptoms started, COVID-19 is proving to be infectious before an infected person shows any symptoms. The first suggestion of asymptomatic transmission was reported in early February. Unfortunately, it wasn’t until late March that consistent studies were showing similar patterns of asymptomatic or pre-symtomatic transmission. This recent understanding explains why universal masking wasn’t announced at the outset of the pandemic. Large-scale public health measures can’t be implemented from one case report or a presumed hunch. The explanation for why asymptomatic spread occurs wasn’t published until April 2020 either. 

Right now, we still haven’t proven that cloth masks protect the people wearing them. There are no specific studies on the utility of cloth masks in the community and there’s only one study on their use in a health care setting. We can hypothesize based on our new understanding of asymptomatic spread that masks may help protect those who unknowingly spread the disease. In early April, Tam stated exactly that. “A non-medical mask can reduce the chance of your respiratory droplets coming into contact with others or landing on surfaces,” she said. “The science is not certain but we we need to do everything that we can, and it seems a sensible thing to do.”

As countries re-open, and economies start up again, the core principles that have allowed the pandemic to be contained, like isolation and social distancing, will become less practical. Physical distancing isn’t exactly possible when you’re getting a haircut. So instead, we’ll have to shift our attention to measures like widespread masking. When better preventative options—like distancing and hand hygiene—aren’t available or practical, wearing a face mask becomes the next best option. Cloth masks are a tool we have in our pockets as our communities across Canada re-open. 

Therein lies the problem with maintaining public trust when a disease is new. The longer we study this virus, the more we understand exactly how it transmits to others. In medicine, recommendations change slowly over time as new information is slow to arise. For instance, we now know opioids aren’t particularly helpful for chronic pain. This is a stark contrast to what I was taught in training 10 years ago and what was understood to be dogma 20 years ago. Patients were given the gift of time to shift their expectations, behaviours and attitudes towards how chronic pain is managed. But the world has shifted its collective attention into understanding COVID-19 in just a short amount of time. This means new information is being released at lightning speed. What used to take years to understand is now taking weeks or months, and our public health experts are digesting and synthesizing this information alongside all of us. 

When new information comes out, it’s critical that public health authorities also shift their recommendations. In court of popular opinion and public trust, this is a lofty ask. But the goal with a pandemic isn’t to remain consistent; it is to respond to new information and changing dynamics.

Those decrying our top public health expert as incompetent, inconsistent and flip-flopping are missing an entire side of understanding this pandemic. We Canadians need to allow our experts to be fluid with their recommendations. A new disease means new information over time. What we should expect from the PHAC however is better communication with the public. One shouldn’t need a medical background to try and dissect the changing recommendations. Clearer explanations of why recommendations are shifting is key to keeping Canadians engaged and maintaining their trust. This pandemic isn’t going anywhere and neither will the need for daily, national information.