By Neil Rau, Susan Richardson, Martha Fulford and Dominik Mertz
The past two months have shown that with major sacrifices, the community transmission of the SARS-CoV-2 virus could be slowed down. In Canada, we can rightfully say that we were able to “flatten the curve” to avert a northern Italy or New York City scenario. Now we face the unintended consequences: delays in medical care for non-COVID-19 patients, educational impacts, the looming pandemic of mental-health issues, and massive economic repercussions. Widespread restrictions certainly cannot be sustained until an effective and safe vaccine is widely available, which may not occur for years, if ever. And the virus is unlikely to disappear from Canada or the world any time soon.
Did the lockdown achieve the desired goals? Yes and no. Success in “flattening” the outbreak curve permitted the health-care system to handle the surge in cases safely and to avoid unnecessary deaths. But, we were not successful in protecting the elderly and frail population in nursing homes, where roughly 80 per cent of Canada’s deaths occurred. It is important to point out that more than 95 per cent of COVID-19 deaths occurred in those over 60, compared with none under age 20. Protection of the former group deserves the most attention; this will be easier if limited resources are diverted from other, low-risk groups.
In Canada, the individual rate of death from COVID-19 for people under 65 years of age is six per million people, or 0.0006 per cent. This is roughly equivalent to the risk of dying from a motor vehicle accident during the same time period. In other countries where data are available, 0.6-2.6 per cent of deaths in people below age 65 have occurred in people without known underlying health conditions. Although the risk of death is small in this group, ongoing research to discover the critical risk factors for death from COVID-19 in younger age groups must remain a top priority. This will permit us to better protect those at risk, while loosening restrictions for the majority.
The virus is unlikely to disappear from Canada or the world any time soon
It is also time to continue releasing lockdown measures. Remember, the original approach of “flattening the curve” was to relax restrictions if the system was not overwhelmed. That is still the appropriate goal. It is unlikely that zero infections can be achieved for COVID-19, which fundamentally spreads like influenza or the common cold, including from those without symptoms. The virus causes disease so mild in many people that it can circulate without detection, until it is introduced into a vulnerable population. While some advocate waiting for a vaccine, that would mean continuation of a lockdown for an unknown period of time. This approach ignores how complicated and difficult vaccine development can be. It is entirely possible that in two years we will still not have a vaccine, and very probable that a vaccine will not eliminate the virus entirely. Hence, we need to come to terms with the fact that we cannot eliminate this virus. At best, we can continue to slow its spread, and protect the frail and elderly.
Governments now propose that we test and trace all contacts of identified cases of disease. As we embark on this stage, we will find cases that would previously have gone unnoticed. Ironically, the better our testing capacity and the more we look, the more we will find, making it appear that disease is worsening, when it isn’t. This is particularly problematic as restrictions are being lifted. Should we automatically reinstate restrictions when the number of cases increases? No. Instead we should use local hospital capacity as the guiding principle, ensuring that all patients who need hospital or ICU care can get it. This is not going to be a one-size-fits-all solution: what happens in an urban centre is different from what happens in smaller cities or rural areas of Canada.
We need a tailored regional approach if the local hospital system gets strained. Germany, for example, chose a local threshold of 50 new cases per 100,000 population per week for when reinstitution of lockdown measures must be considered based on local capacity. The Ontario equivalent using the same threshold would be 7,300 new cases per week, or 1,043 per day. In contrast, Ontario has recommended a much lower provincewide threshold of 200 new community cases of infections per day as a threshold for action. This is based on an estimate of the ability of the system to accommodate the required contact tracing for every diagnosed case at the provincial level. The number of community cases should not be the metric of choice for relaxing restrictions as it is not a reflection of the more critical measure, hospital capacity. In addition, time spent on contact tracing is neither necessary nor feasible for all community cases, as it misses asymptomatic and covert transmission. Instead, testing and contact tracing should be focused mainly on hospitals and long-term care institutions, where the impacts of disease are the highest.
Accepting ongoing sustainable levels of transmission might be a healthier option in the long term. While the lockdown has decreased transmission of the virus in the short run, it has also prevented the development of population immunity in low-risk people. We should embrace the benefits of the development of immunity in a growing segment of the population. Right now, the only means of achieving this is by natural infection. Recent data suggests that the human body reacts no differently to this virus than to other respiratory viruses: it mounts immunity, and once achieved, the virus gets cleared and there is protection from future infection. Given the novelty of the virus we do not have long-term data, but we know from 2003 SARS that immunity may last up to 13 years. Once a vaccine is available that would be the preferred option. However, there is no guarantee of whether and when a vaccine will be available, or how effective it will be, to say nothing of how broad the uptake of it will be in the population.
Will this approach cost more deaths? Sweden, which allowed for more community transmission, is the measure of this strategy. More deaths per capita did occur than in Canada. On the positive side, Sweden’s number of new cases has peaked and Sweden will be better protected against future waves and the need for future restrictions. In the absence of a vaccine, it is a question of paying now or paying later. While the realistic goal of Canada’s lockdown was to delay deaths, it was never going to avoid them entirely. One year from now, Canada and Sweden may well have the same number of deaths per capita, but Canada may have had significantly more economic and social impacts.
Canada needs a model that uses a hospital capacity-based approach to guide local lifting and reintroduction of more restrictive measures, as necessary. In the absence of hospital strain, consider continuing with a swift release of lockdown measures, to include opening of elementary schools, playgrounds, workplaces, stores and restaurants, while following basic physical distancing rules and voluntary limitations to social gatherings, while continuing to ban mass gatherings and protecting the elderly and those at highest risk.
Dr. Neil Rau is an infectious diseases specialist and medical microbiologist in private practice in Oakville, Ont. He is also an assistant professor at the University of Toronto. Dr. Susan Richardson is a retired infectious diseases physician and medical microbiologist and professor emerita at the University of Toronto. Dr. Martha Fulford is an associate professor at McMaster University and an infectious diseases physician at Hamilton Health Sciences. Dr. Dominik Mertz is an associate professor at McMaster University and an infectious diseases physician and hospital epidemiologist at Hamilton Health Sciences.
Source: Lire l'article complet de Vigile.Québec
