How we can keep COVID down
We have now endured close to seven months of this pandemic, the likes of which almost no one in the world has seen in their lifetime. In this short period of time, we have seen staggering developments on the research front — knowledge that continues to accumulate to this day.
Looking back to March when much of Canada entered a lockdown, though things have not been perfect, our overall response was successful. We now have very low levels of disease transmission across the country, and are currently in the midst of a slow, deliberate return to something closer to normalcy.
This process is a complicated one, which at times may result in us having to re- evaluate our progress. At this phase in the outbreak it is safe to say we have passed the first wave. We now must recalibrate our goals and expectations during this pre-vaccine era to a world living with COVID-19, albeit one where we continue to strive to keep rates of infection as low as possible in community settings. There are four important concepts to consider in the coming months.
The Hammer and the Dance
Tomás Pueyo wrote a prescient article in March referring to a phased approach to controlling and maintaining the outbreak that he called “The Hammer and the Dance.” The “hammer” aims to get the rate of COVID-19 transmission as low as possible, as quickly as possible, accomplished through the lockdown imposed back in March. This eventually worked, bringing us to low levels of disease transmission across the country. We are currently in the “dance” phase where the goal is to preserve this low transmission, aiming for a reproductive “Rt” rate (how many people on average an infected person passes the virus to) below one.
Here, we dance with the virus by closely monitoring transmission, responding to outbreaks quickly to quell the small fires before they become big ones, and apply future policy based on the lessons learned from these events. During this “dance” phase, we should expect outbreaks. They will happen. Rapid identification of these is a sign that our system is working. Take for instance the recent outbreak at a nail salon in Kingston, Ont. Public health quickly reacted to the outbreak, with rapid case detection, contact tracing and focused isolation. Outbreak control was swift and effective.
This process of rapidly responding to outbreaks is used by countries that have successfully managed their epidemics and have the infection under relatively good control. With early detection systems, and sufficient testing capacity, we are afforded the ability to identify outbreaks early, and if needed, reintroduce public health measures with precision, rather than globally.
Remember the
Big Picture
Across Canada, there are news reports giving us daily
COVID-19 case counts. More often than not, words like “spike,” “uptick” and “surge” are deployed when there are more cases today than yesterday, and “plummet,” “dip” and “drop” when fewer. These terms provoke undue anxiety or relief, but in reality all miss the big picture. Like the stock market, a clearer idea is obtained by looking at the longer-term trends, such as seven- day averages, in addition to other metrics.
Whether there are 170 cases today, 130 tomorrow and 190 the day after does not matter as much as the fact that this is lower than the 400 cases a day from a month earlier. The situation has greatly improved in Canada with each successive month, and this is only appreciated when looking past the proverbial trees to the forest.
This is where the Rt rate is a useful metric. The goal is to keep this number at or below one to ensure cases are stable or declining over time, and at present, this is where we are in most of Canada. This value, however, can be misleading when there are a low number of cases. As the number of cases decrease below a certain threshold, small changes result in relatively large swings of the Rt, which leads to anxiety around explosive growth in localized regions. Once again, it is important to not look at one value in isolation; rather a compilation of metrics over time to gain a more holistic and accurate picture.
Explosive growth does not happen
overnight
On Feb. 18, in northern Italy, the first case of COVID-19 was diagnosed in a healthy 38- year- old male. He was dubbed “Patient 1.” A short time thereafter, this area of Italy experienced an explosion of COVID-19 cases that overwhelmed the health-care system, sickened thousands of people including hundreds of health- care workers, and took weeks to get under control. Looking closer, Patient 1 was more likely Patient 100, or possibly Patient 1,000. When all eyes were on China in early 2020, COVID-19 was already circulating in northern Italy. It took weeks of undetected (and therefore uncontrolled) spread before the country was in the grips of the explosive epidemic growth. By that point, even with extreme measures such as a lockdown, things got a lot worse before they eventually got better.
In Canada, our measures, including the lockdown, were able to largely avoid this terrible scenario, but there is still fear it could happen if we get complacent with our public-health measures such as physical distancing, indoor mask wearing and good hand hygiene. This concern has been magnified across the country in the last few weeks, with multiple regions relaxing restrictions along with increasing outbreak clusters. These clusters, however, do not progress to exponential growth overnight. To have a scenario akin to what happened in northern Italy or New York City, you would need weeks of uncontrolled spread. With our current testing capacity and availability, as well our ability to track, trace and isolate clusters, this is an unlikely scenario here in Canada.
We may get clusters of infection and provinces may even need to walk back on some of the reopening plans if there are a large number of cases, but this would happen long before we ever get to a situation of exponential growth overwhelming our health- care systems. Nevertheless, it is imperative to continue practising the principles of COVID-19 prevention including physical distancing, good hand hygiene and masks in indoor public places.
Low community transmission means a lower risk for everyone
Dr. Mike Ryan of the World Health Organization recently, and very insightfully, remarked that the best way we can protect people against COVID-19 is by having low community transmission. This obvious point cannot be emphasized enough. When there is a low burden of COVID-19 in a given area, the risk of acquisition will be substantially reduced for everyone, and for every activity. It is only under these low- burden circumstances where allowing higher- risk venues (such as schools, indoor dining, bars, etc.) to even be considered for reopening. These decisions, given the protection from low prevalence environments, cannot be applied in a subjective manner. Evenly distributed as well as evidence-based infection and control policies should be applied to most settings with a goal to give institutions and businesses a chance to open up safely while community transmission is low. Today in Canada, the chance you have of contracting COVID-19 in the community, though not zero, is the lowest it has been since the start of the pandemic. This is the time to arm ourselves with the power and courage to cautiously lift restrictions on higher- risk activities, without descending into an explosion of cases, with the understanding that this reopening may be reversed if (or when) case numbers rise.
A Final Thought
By this point, it should come as no shock that COVID- 19 will be a significant part of our everyday lives for some time to come. Many things have changed in a dramatic way, and some may never be the same again. A vaccine and/ or effective treatment cannot come soon enough. Canadians have come together at great personal sacrifice to endure a lockdown, and ultimately the first phase was successful. There is a very understandable reluctance to lift restrictions for fear of a resurgence, but if anything, now is the time to do it with careful planning and monitoring, and with a goal to keep community cases as low as possible.
There will be a continual ebb and flow of COVID-19 cases in the coming months. The so- called dance allows us to adapt with the circumstances, including safeguards to prevent infection rates from spiralling out of control. To do this successfully we must continue to look toward the long- term trends and recalibrate our expectations on what is to come.
WE SHOULD EXPECT OUTBREAKS. THEY WILL HAPPEN. RAPID IDENTIFICATION OF THESE IS A SIGN THAT OUR SYSTEM IS WORKING.
Dr. Sumon Chakrabarti is a lecturer at the University of Toronto and an infectious diseases consultant at Trillium Health Partners, Mississauga. Dr. Zain Chagla is an associate professor at Mcmaster University and infectious diseases consultant at St. Joseph’s Healthcare Hamilton. Dr. Isaac Bogoch is an associate professor at the University of Toronto and infectious diseases consultant at Toronto General Hospital.