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black lines with green dots showing how we are connected to other people

September 10, 2020 - Dr. Archer's Update on COVID-19 response from the DOM and Medicine Program

Today’s Headlines

  1. Bubbles-on the challenges of departing from physical distancing by adding another friend to your group
  2. Vaccine update

Can’t I visit more friends? Goodreau et al recently published an online article that discusses the challenges for COVID-19 control that would occur if we expand our bubbles too much (click here). In other words, if you want to socialize more, what are the consequences for disease spread? First, the positive news: physical distancing, hand washing and use of masks in indoor space are quite effective in preventing the spread of this droplet-born infection. To get infected with COVID-19 one needs to be in sustained contact (i.e. 15 minutes or so) with an infected person, and not wear a mask and or not wash your hands. So, if you want to socialize please follow these precautions!

The diagrams Goodreau created are helpful in understanding the potential for disease spread under different scenarios. These network scientists show diagrammatically what society looked like pre-pandemic (see below). Each household (the green dots) was modeled to be connected to 15 other households each day! The diagram shows how interconnected we all used to be (sigh). SARS-CoV-2 virus loves this model-easy spread from household to household!

black lines with green dots showing how we are connected to other people

The next diagram shows what would happen if each household were completely isolated. Note none of the green households is connected. In this model there would be no pandemic, since there would be no contact and no chance of transmission (but we would all be sad, lonesome and unemployed!). This model is not feasible for practical reasons nor is it desirable from a human wellness perspective. 

circle of green dots showing the connection of people with isolation

The next diagram is closer to what we actually did in Ontario. We told most people to stay home; but had essential workers (blue dots) come to work. This allowed society to function, at the cost that there was still some opportunity to spread the virus (more connections between dots). The policy was successful in that we not only “flattened the curve” but actually ended the first wave of the pandemic in Canada.

circle of green dots connected by only a few purple lines and dots

Round about July we all began to long for more social contact and Ontario entered the bubble phase where we could socialize with our 10 besties. The next diagram shows what would happen if an average of two people in each household decided to maintain an in-person connection with one person from another household. As you can see, our village of households is once again a very connected network, with a high risk of viral transmission.

circle of green dots with interweaving of lines and purple dots

What if we were little stricter and allowed households to have one friend outside their network? Well its better (see below), but still we are connected enough to enhance spread.

circle of green dots with connecting lines and purple dots

The authors acknowledge that their model is reductionist (household are more complicated than their model allows for and they don’t factor in the powerful preventative effects of masks, distance and staying away when sick). 

So what to do with this information? My advice is to follow public health guidelines, continue masking in indoor spaces, be diligent in washing your hands, maintain physical distancing of 6 feet, stay home if symptomatic and recognize that yielding to the temptation to let down our guard will not allow us to control the disease. If we can continue to follow these nonpharmacologic preventative measures a bit longer, while we await a vaccine, we should be able to continue our Phase 3 practices, safely restart our schools and continue operating our businesses (and maintain a reasonable social network). We can however expect starts and stops as outbreaks occur. On the issue of outbreaks, careful attention to contact tracing will be needed for the foreseeable future. We can each help by accurately providing business with our names and phone numbers when we visit an establishment (so they can contact you should an infection occur). The COVID-19 tracking app is also potentially helpful (more on this in a future note).

Vaccine update: The government of Canada has secured access to potential future vaccines from two large Pharma companies (J&J and Novavax). These companies have vaccines in early phase trials (phase 1 and 2 clinical trials) and thus the wait for access to these potential vaccines could be substantial. In contrast, Astra Zeneca has a vaccine that is in phase 3 testing, the final stage of testing before approval and marketing. Astra Zeneca is close to having the capacity to deliver 3 billion doses, assuming the vaccine proves safe and effective in the clinical trial.

(click here)

screenshot of man standing at podium

However, their trial was just paused as researchers try and determine whether the vaccine is associated with a rare side effect, called transverse myelitis in 2 of 30,000 volunteers. Transverse myelitis is an immune disease which damages the spinal cord by attacking the insulator material around nerves, which is called myelin. Transverse myelitis causes loss of sensation and weakness in the arms or legs and may result in bowel and bladder dysfunction. Most people with transverse myelitis, whatever the cause, recover at least in part within 3 months. The cause of most cases is unknown, although there are often auto-antibodies, such as anti-aquaporin-4 detected. Many affected people have had viral infections or have an autoimmune diseases. Although transverse myelitis can occur after a vaccination; usually condition also occurs spontaneously. Thus, it is only truly possible to implicate a vaccine is the cause of this disease if it causes a cluster of cases (i.e. more cases than would be predicted to occur spontaneously). Transverse myelitis usually occurs in younger people (< age 40 years). It is estimated that about 1,400 new cases of transverse myelitis are diagnosed each year in the United States (click here) and most are unrelated to vaccines.

The Astra Zeneca trial plans to ultimately study 60,000 people so that it has the statistical power to detect even rare side effects, like myelitis. If there are only 2 cases in this large trial this will not be a barrier to continuing on with the development of this vaccine. In fact, it is reassuring that the urgency to develop a vaccine is not causing a compromise in attention to ensuring safety. In light of the unfortunate anti-vaccine movement in society it will be important to be able to unequivocally state that the vaccine that is finally licensed is not only effective but also safe.

Local COVID-19 Update KFL&A: 

There have been 112 COVID-19 cases in our region since the pandemic began in early 2020. Currently there are 2 active cases locally and they are recovering in the community (see update from KFL&A Public Health) (see graph). I mistakenly in tweet that there were no active cases yesterday.

chart showing current COVID-19 cases in KFL&A

COVID-19 in KFL&A; 2 active cases recovering in community

We have performed 3132 COVID-19 tests in past week at KHSC. Two tests were positive (both from the Kawartha area and none from KFL&A). There are no inpatients with COVID-19 in KHSC. We are seeing greatly increased community demand for testing at our assessment centers. Since Sept 1 we have tested 2500 people at Leon Center. Increasingly these people are symptomatic. For example, we did 373 tests at the Leon’s center yesterday and over 200 of these people had symptoms. We hope to open a satellite testing centre at Queen’s within ~ 1 week at Mitchell Hall. This will be for symptomatic students or students who are part of contact tracing. This is not favouritism toward Queen’s university students; rather it is an acknowledgement that university age patients are a key demographic and one which if not properly managed can lead to large COVID-19 outbreaks. Thus KHSC is enhancing testing of this at risk population.

Care of the 99%: At KHSC operations are stable, our PPE supply is good and we are making progress in increasing our capacity for elective care for the 99%. However, our outpatient clinic volume remains at ~50% of what it was pre-COVID-19. We recognize the urgency of increasing our ambulatory patient capacity and are striving to get to ~70% of pre-pandemic capacity, with the balance of clinic visits being provided by virtual care (telehealth and video visits). 

Ontario’s COVID-19 epidemic: (click here) (see map below) Ontario’s COVID-19 prevalence rate is 295/100,000 up slightly from a month ago when it was 263.8/100,000, and much higher than in KFL&A, which has a prevalence of 53.1 cases/100,000 population. Toronto has a rate 9 times higher than Kingston (487.7 cases/100,000 population). The region with the highest prevalence of COVID-19 remains Windsor (601/100,000), largely because of a poorly regulated agricultural sector and suboptimal housing of farm workers.

map of ontario showing COVID-19 prevalence

There were 170 new cases of COVID-19 in Ontario yesterday (up 0.4% from the day before). Ontario has had a total of 43,855 total cases and 2841 deaths to date. The 1.0 % rate of positive SARS-CoV-2 tests yesterday (down 0.3% compared with prior day) continues at a stable low rate over the past month, consistent with the first wave of the epidemic being controlled. 

SARS-CoV-2 is a litmus test for social inequities: consider the epidemic in Toronto (click here). Toronto remains a collection of neighbourhoods with vastly different COVID-19 realities due to differences in social/economic, racial and health circumstances. For example, the Beaches has 88 cases of COVID-19/100,000 residents whilst Weston has 1906 cases/100,000! Thus, there is no single “Toronto”, as seen through a COVID-19 lens; it’s a diverse patchwork with a >20-fold variation in disease prevalence.

Toronto Skyline with CN tower and Rogers Centre

The epidemic is gradually improving in Toronto (overall), but will persist until we are able to deal with these local hotspots. 

COVID-19 is affecting certain racial groups disproportionally. Note the disproportionate burden of COVID-19 in Toronto amongst people who are of Arab descent, people who are Black, people who are of Latin American descent and people of Southeast Asian descent (see graph below) (click here). The best way to stop the epidemic in Toronto is to address housing conditions in its poorest neighbourhoods and focus on broader equity and inclusivity initiatives.

graph of ethnographies racial groups with COVID-19 vs Toronto

The first wave of Canada’s epidemic is resolving (although there is an increase in cases in Alberta, BC and Saskatchewan in the past week) We have had 134,653 cases of COVID-19 in Canada and 9158 deaths (see below). Most cases (89%) are resolved. The situation in Canada remains good, with low levels of hospitalization, low rates of new cases (top right below) and most cases resolved (bar graph bottom left). The rate of new cases remains low nationally (bottom right panel).

chart and graph showing current Canadian aggregate data

Canadian aggregate data Sept 10th 2020

There are however concerns about focal outbreaks on farms in Ontario, increases in disease incidence in the Western provinces, like BC, and hotspots within large cities, like Toronto. 

graph of active COVID-19 cases In BC

Uptick in active COVID-19 cases in BC-Sept 10th (orange line)

A reminder: we remain as susceptible to this virus as we were last year! There is little immunity amongst Canadians. This reinforces the need to continue to practice physical distancing, hand washing and use of masks when in doors. It does also remind us of the importance of targeted public health interventions. Nonetheless, these data support the wisdom and safety of carefully reopening Canadian schools. 

Long term care facilities: The epicentre for COVID-19 mortality remains our long term care facilities (LTC) (see today’s data below) (click here). The ~78,000 residents of Ontario’s LTC facilities account for less than 0.5% of the population but they still account for ~67% of all deaths from COVID-19! There have been 1848 deaths to date. There have only been 3 deaths in Ontario’s LTCs in the past month (and none since my last report September 3rd). 

COVID-19 testing: Ontario SARS-CoV-2 testing continues at a rate that exceeds the national average (17.8%), with 22.2% of Ontarians having been tested ( click here). Our positive test rate remains low.

graph showing daily COVID-19 tests performed in Ontario

In contrast with Canada’s 2.0% rate of positive tests, the USA has an average rate of positive COVID-19 tests of 5.1%. In Illinois the positive test rate is 3.8% while in New Jersey the rate is better than Canada (1.3%). I selected these states because I have family living in each state. This is an encouraging decrease in the rate of positive tests in the US, down ~ 2-3% over the past month (click here). Nonetheless, the US-Canadian border remains closed for routine travel at least until the end of the month. 

The COVID-19 global pandemic: There are now 27,933,388 cases globally and there have been 905,181 deaths. The pandemic hot spots are in the Americas (Brazil, Mexico, Peru, Chile and USA), India and Russia (click here). The USA with 6,373,349 cases alone accounts for 23 % of the global pandemic. India now has the second largest number of cases (see list of countries with 100,000 cases below).

list ranking countries with 100,000 or more

Stay well!

 

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