July 6, 2020 - Dr. Archer's Update on COVID-19 response from the DOM and Medicine Program
Important update (new outpatient cases)
Local COVID-19 Update KFL&A:
As everyone likely knows we have had a local outbreak of COVID-19, largely related to infections acquired in nail salons. This outbreak, though unfortunate, does not indicate a reversal of the gradual improvement in the epidemic we are seeing across Canada and in Ontario. It is not a cause for panic, although it has triggered a change in public policy, requiring public masking in indoor spaces (at Queen’s University and in all places of business in our region). It is also a reminder that the virus is circulating and maintaining physical distancing and hand washing (plus masking in indoor spaces) are required.
The running total for the epidemic is now 105 cases in the KFL&A region (see update from KFL&A Public Health) (Table below). This reflects 42 new cases, 37 related to contact with Binh’s nail salon and Kingdom Nails & Spa. However, 5 new cases are not associated with outbreak (1 related to international travel, 3 with Toronto connections and 1 in a person from Leeds-Grenville-Lanark). Over the past 3 days we have performed 1364 SARS-CoV-2 tests. There were 3 positive test, 1 from KFL&A and 2 from the Kawartha area. Our test positivity rate in KFL&A continues to fall and is currently ~0.2%. The Leon Centre testing facility has tested 1550 patients in the past week. The demand for testing is slowing as all nail salon contacts have been tested; however, LTC workers are now returning for repeat testing, per protocol. The wait time at the Leon's Centre is short (10 minutes); the only exception being if there is a line-up before the centre opens.
There is one patient with COVID-19 in KHSC on Connell 3. All other cases are recovering from COVID-19 in the community. The Davies 5 quarantine has been lifted and there was no evidence of transmission related to the single staff member who had contracted COVID-19 in the community and worked part of a shift on Davies 5. Our COVID-19 ward is Connell 3. This ward has 35 beds and many single rooms. Dr. Chris Smith and Dr. Gerald Evans have worked with IPAC and KHSC to ensure that we have a hot zone on this ward (for patients with confirmed COVID-19 when/if they arrive) which is separated from a warm zone (for people being tested for COVID-19 but not confirmed to be positive). There is also a physically separated cool zone, which will have separate staff. This cool zone is for people not infected or suspected of COVID-19 infection.
KHSC has good capacity to deal with a potential COVID-19 surge, with adequate beds and ventilators on hand.
Symptomatic KHSC staff: Should KHSC staff develop symptoms consistent with COVID-19, please contact occupational health and safety and they will tell you how to proceed (ext 4389 at KGH site, or email COVIDrtwadjudication@kingstonhsc.ca). You will likely be tested at the Hotel Dieu testing centre. Do not come to work!
FAQ: Is COVID-19 a disease transmitted by aerosols”? or, “Can chickens fly?”:
Our infection prevention practices in Canada (both in the community and in hospitals) are based on evidence that the predominant way COVID-19 spreads is by inhaling airborne droplets from a nearby infected person. These droplets don’t hang in the air very long and are transmitted when one is in close proximity to an infected person (< 6 feet). These droplets largely originate from the nose and upper respiratory track. N-95 and surgical masks effectively prevent both droplet and aerosol routes of transmission and cloth masks may (or may not) be effective. However, these medical grade masks (especially N-95 masks) are in short supply and are both expensive and uncomfortable to wear.
The debate about droplet vs aerosol transmission has generated more heat than light and is a bit of a false controversy. Droplets and aerosols are not apples and oranges, they are different sized apples! These particles exist on a spectrum but that spectrum is predominated by droplets in most cases. The World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) defines droplets as particles that are greater than 5μm in diameter vs aerosols, which are defined as being particles less than 5μm in size. Both sizes of particles (droplets and aerosols) are potentially emitted by coughing, sneezing or exhalation into the air. They differ in their size and ability to hang in the air. If an infection were spread by aerosols it could be contracted by simply walking through a room where a sick person had been, even if they left the room minutes or hours before. In contrast, if droplets were the main means of disease transmission, one only be at risk of infection if present in the room with the person and within the 6 foot range of droplet transmission (beyond which gravity pulls the droplet to ground) (see diagram below).
Click here for source document
The epidemiology of COVID-19 and the efficacy of physical distancing and handwashing in preventing transmission largely supports a predominant droplet mode of transmission. The N-95 controversy (which was about the widespread use of these masks, rather than about their accepted use in care of COVID-19 infected persons) had died down. However, the controversy has risen again recently because of a petition being circulate to have the WHO change its position from stating that SARS-CoV-2 is a disease transmitted by large droplets to one indicating it is spread by aerosols (click here). The fact is of course that both the WHO and this group of scientists are both a little right and a little wrong. The debate should not be about whether virus can be aerosolized but whether this is how it normally spreads. The reason the predominant mode of transmission matters is that this “truth” determines our public health policies (and its much harder to defend against an aerosol).
If large droplets are the culprit and fairly close and sustained contact is required to transmit disease, cloth masks, distancing and handwashing should work. Indeed it is our belief that the virus is spread by these large droplets that is the basis for the advice to have 6 feet of separation from other people. Usually droplet borne infections (like influenza) are less “catchy” (infectious) than airborne diseases. This is largely how COVID-19 behaves in the real world. The vast majority of cases are contacted by close and relatively sustained contact; however, there are likely rare infections due to some aerosol route of infection in the community. I am not in this discussion dealing with = intubation and endoscopy, procedures where aerosolization definitely occurs and for which medical personnel where appropriate masks.
While COVID-19 can be nebulized (by intubation for example) the overwhelming evidence is that this mode of transmission is extremely rare. Almost all cases are spread by droplets. Were this not the case we would see much different epidemiology and different contact tracing results. It is the requirement for close proximity for example that makes a nail salon a high risk site for COVID-19 transmission if a worker is infected. If the infection were aerosolized then the R0 (the infection reproduction rate) would be much higher (>10 instead of the observed 2). Thus, there is a vast difference between what is possible and what actually occurs. Here is a thoughtful post on the subject from Controversies in Hospital Infection Prevention
“But we know (and WHO experts know) that there is no such dichotomy—it’s more of a continuum. At the very least there is a middle category, let’s call it Small Particle Aerosol Transmission (or SPAT). Many respiratory viruses (not just SARS-CoV-2) can remain suspended in aerosols and travel distances > 6 feet. As Jorge outlined, it’s probable that transmission events occur when these aerosols are concentrated in closed, poorly ventilated spaces or in very large amounts (e.g. a 2+ hour choir practice, a 3 hour indoor birthday party, a crowded bar). This may explain the superspreading events that drive a lot of SARS-CoV-2 transmission. It’s important to distinguish SPAT from “classic airborne transmission” (let’s call it CAT). The CAT pathogens (TB, measles, VZV) have very different transmission dynamics than SPAT pathogens, as I outlined here (R0s of >10, household transmission rates of 50-90%). The distinction is important because for most healthcare epidemiologists, using the term “airborne” implies a common set of “one-size fits all” interventions to prevent transmission, interventions that require resource-intensive engineering controls and PPE requirements. It is not at all clear that such interventions are required to prevent transmission of SPAT pathogens. In fact, most evidence (and real world experience) suggests that they are not. This is why the droplet-airborne dichotomy has served us fairly well over the years—either because droplet precautions appear to be pretty effective at preventing SPAT, or because SPAT is rare even among those viruses capable of it.”
This leads to my analogy. Asking whether SARS-CoV-2 can be aerosolized is like asking, “Can chickens fly?”. The answer is “Yes”, but not far and not often”. This knowledge has guided barn yard design for a millennium! There is a reason farmers allow chickens to wander the barnyard without fear of them flying away! So to with COVID-19, it can fly through the air…but like the chicken it mostly travels in droplets that retune to earth within 5-6 feet. To not thoughtfully differentiate between the usual (droplet transmission) versus the exceptional (aerosol transmission) would lead infection prevention policies that would like achieve little and cost a lot or be impossible to implement.
Kingston’s COVID-19 outbreak (click here) Our disease prevalence in the KFL&A region has risen to 48.9 cases/100,000 population. Toronto still has a rate ~8 times higher (430.4 cases/100,000 population). The prevalence in Toronto has increased every day for the past month, reflecting neighbourhood hot spots. Provincially the epidemic is in modest decline. There were 154 new cases yesterday (up 0.4% from yesterday). Ontario has had a total of and 35,948 total cases and 2689 deaths to date. The 0.9% rate of positive SARS-CoV-2 tests is the lowest rate to date. All good news!
The prevalence of cases in Toronto is still increasing daily due to over a dozen neighbourhoods which are COVID-19 hotspots, defined as rates over 1000 case/100,000 (click here), including: Moss Park, Newton Brook West, Yorkdale Glen-Park, Downsview Roding CFB, Maple Leaf, Rexdale-Kipling, Black Creek, Mount Olive, Beechborough, York University Heights, Mount Dennis, Glenfield Jane Heights, and Weston. Humber Heights Westmount with 1772 cases/100,000 once again has the highest prevalence in Toronto. The ministry has deployed public health experts, mobile testing facilities and contact tracers to deal with these “epidemics within epidemics”.
How’s Canada’s epidemic going? We have had 105,764 cases of COVID-19 in Canada and 8687 deaths (see below). As seen below, most cases are resolved (88%, green) (top left below). The number of active cases per day is declining slowly (bar and line graphs, below right). Quebec remains the hot spot (below left).
Canadian aggregate data
The epicentre for COVID-19 mortality remains our long term care facilities (LTC) (see today’s data below). The ~78,000 residents of Ontario’s LTC facilities account for less than 0.5% of the population but they account for 68% of all deaths from COVID-19! There have been 1821 deaths to date; but there were no deaths since yesterday in Ontario LTC centres. Canada had the highest rates of mortality in LTCs of any survey country. 81% of all COVID-19 deaths occurred in residents of LTCs (click here)! This is sad, embarrassing and requires rapid change in how we license, fund and monitor LTCs.
Testing for SARS-CoV-2 (click here): We have tested 7.32% of all Canadians (3,183,604 people). Nationally, 3.31% of all tests are positive (vs 2.34% in Ontario). Ontario SARS-CoV-2 testing (see below) continues at a rate that exceeds the national average, with a rate of 10.7%.
The COVID-19 pandemic has exceeded 11 million cases. The pandemic hot spots are in the Americas (Brazil and USA), Russia, UK and India (click here). The global case total is 11,495,412 and the number of death is 535,185 (click here). July 4th saw the most new cases globally of any day since the pandemic began!
America: I have children and many friends and colleagues in the United States and so I report the data below, once again, with great concern (click here). The failure of leadership in America regarding implementation of a national public health response to the pandemic has been spectacular and the COVID-19 incidence is rising in proportion to this. These are concerning times for our friends, family and colleagues in America. The graph below shows cases/million population (linear plot, 7 day average). We will not be seeing the border opening in the near future.