April 21, 2020 - Dr. Archer's Update on COVID-19 response from the DOM and Medicine Program
COVID-19 Update: There are no new cases locally today. But over the weekend we did have 1 case from the community and 1 at Providence Manor. There are 2 COVID-19 patients in KGH today. Yesterday 368 SARS-CoV-2 tests were performed at KGH and 9 were positive; however, none were from the KFL&A region. As was the case last week, these positive tests were from communities further to the west (Peterborough) and north (Perth Smith Falls).
Thus, although our local situation remains very positive with a flat incidence curve, the virus is in our community and physical distancing remain crucial. If you are sick with symptoms of an acute respiratory illness (new cough, fever, sore throat or if you have had contact with a COVID-19 infected person) you need to self-quarantine and seek out testing in our community facility (Memorial Centre). Located centrally with access to ample parking, the COVID-19 Assessment Centre at the Memorial Centre operates 7 days a week be (10:00 a.m. to 8:00 p.m). Public health is seeing ~60 people/day at Memorial Centre and are performing PCR testing on over 90% of those people (i.e. 56/60 who show up for screening are being tested).
Please remind patients that our hospitals and clinics are very safe (in part because everyone including staff is screened prior to entry and in part because the local incidence of COVID-19 remains low). Patients should not delay accessing care that they or their doctor deems critical or semi urgent.
We continue to plan for a field hospital to be ready for second waves and worse case scenarios. Hopefully we will never need this facility. The location will be made public later today.
COVID-19 testing update: Nationally 594,747 tests have been done(with a 6.19% rate of positive tests; see below). Testing is much more often positive in Quebec (11.31% of all tests in that province are positive for COVID-19). The criteria for testing are changing and becoming more liberal (i.e. we are testing more people who have less typical presentations).
Canadian COVID-19 epidemiology: 4.62% mortality rate in Canada
To date we have had 37,382 cases of COVID-19 and 1728 deaths related to COVID-19 in Canada. (click link for daily update). There are 22,765 active cases and 21.9% of them are in ICU.
To see where Canada stands amongst nations around the world, click here. As judged globally, Canada’s mortality rate is lower and rate of testing higher than many comparator countries (see Table below). However, we are in the middle of the pack when it comes to the number of new cases per million people, so it’s not the time to declare victory!
It is noteworthy that the basic epidemiologic truths that originally emerged from China’s COVID-19 experience are holding up. For example, the vast majority of new cases are resulting in mild illness, with only 3% being deemed as severe (see below).
Reopening act: Why expanded testing is at the base of attempts to reopen our society
To safely reopen Canada we need 4 things:
- An expanded detection strategy (PCR testing for SARS-CoV-2)
- A clear idea of our herd immunity (antibody testing to accurately know how many people have been exposed and developed immunity)
- An more precise quarantine strategy (for those who are infected, not for everyone else) and
- a reinvigorated health care system (with more virtual visits and a more robust supply of PPE).
Increased testing sounds easy but it’s not. First let me say KHSC and KFL&A are leading nationally in testing (high numbers of a reliable test are being performed multiple times per day). While testing criteria is gradually being liberalized it is still mostly being used to evaluate people with infectious symptoms. Canada, as a whole, will need to do much more testing to paint a truer picture of the epidemic and this will require both more real time PCR testing (to say who is infected now, so they can be quarantined) and serologic testing (to say who was infected previously and is now immune and safe to return to work).
Currently we are essentially in a car that lacks both a front windshield and a rear-view mirror. While we know how many cases of COVID-19 we have diagnosed and how many of these have died or recovered we don’t know how many people were actually infected. Many estimate there are many times more people infected than we have diagnosed. Until we establish the true denominator, how many were infected (even if there were no symptoms or mild symptoms), we don’t really know if the true mortality rate is 4.6% or one tenth that value. If testing were to show that there are many undiagnosed people who have been infected, then the true case mortality rate would plummet. If we’re going to get Canada’s “car” (i.e. schools business and other vehicles of social stability) back on the road we need enhanced testing (front and rear views are required)! NOTE: Canada does love vehicles without front windows or rear-view mirrors-but they are only suitable for use on ice!
When monitoring pandemics (or other alpha predators) we need to know what’s going on around us (see below)!
Are lab tests the only detection option? Some suggest we could rely on smartphone tracking, as is being done in Taiwan. In this way if a person later becomes COVID-19 positive everyone they contact can be traced, notified, tested and quarantined. I personally think we are better off with the ravages of COVID-19 than this misguided Orwellian approach. This is not testing it’s a form of contact tracing. In my opinion it would put way too much authority into the hands of initially well-intentioned corporations like Apple and Google (and our own government). Plus, this strategy doesn’t detect COVID-19-it detects us! Cell phones will not free us from the need for effective, and likely recurrent, mass COVID-19 testing. I hate to agree with American Republicans but I do (a recent article in Vox suggests 70% of them oppose this strategy).
So what of increased testing. Some have advocated for repeated testing of everyone, with quarantine of all people who test positive and extensive contact tracing. Dr. Paul Romer, recent Nobel Laureate in economics and NYU professor, has modeled two extreme versions of models that both prevent the spread of COVID-19. In one model, we keep society largely shut down and maintain extreme physical distancing practices (i.e. we are all effectively quarantined); in the other model everyone is tested for COVID-19 every 2 weeks. Make no mistake this strategy would be expensive (but so is shutting down society) and we would need a testing capacity we currently lack. Here are his results. The % of society that would be quarantined is on the vertical axis and time in days is on the horizontal axis. Note that if everyone were recurrently tested his models predict quarantine would become rare (and only the infected would be quarantined-top panel). Conversely the lower panel reflects current practices, namely, selective testing of the sick with many people effectively quarantined.
If you visit his site you see that in the massive testing model the people that are quarantined are largely infected people…and many fewer people are quarantined!
Testing comes in two general types, molecular testing (measuring the viral RNA by PCR-which if positive shows viral presence, meaning there is an active infection). This is the assay we use at KHSC and KFL&A. It is precise, valid and specific for SARS-Cov-2 (there are many other coronaviruses out there that don’t cause COVID-19). This test is our front window-telling us where we are.
Our rear view mirror are the antibody based tests. For an antibody test to be positive you have to have time (days) to mount an immune response to the virus. During acute infection the antibodies may not have been formed. Thus, antibody test are not designed to diagnose new cases, rather they are designed to detect who has been infected and developed immunity. There are 9 or more antibody tests out there and their performance characteristics are still undefined. They may however offer the benefit of identifying who may be immune to infection upon re-exposure. The NIH in the USA is launching a study using blood antibody detection to determine how many people have been infected without having symptoms or at least without having been diagnosed
Example of a point of care antibody test for COVID-19
Even with 2.5million people known to have been infected (as of this morning), most of the planet’s 6 billion plus people have not been infected and thus are vulnerable to future waves of infection. With testing we can identify whether there are asymptomatic people who have been infected and who are immune. This is critical information since the ultimate resolution of the COVID-19 pandemic will be some combination of a vaccine, effective treatments and/or herd immunity. Herd immunity occurs when most people are immune because they have either been infected or vaccinated. Herd immunity means the virus can’t spread effectively because it will often encounter immune people. Antibody testing is useful both to understand how immune the herd is and and to identify individuals who are immune. The herd immunity concept is illustrated in the Figure below (from the US Health and Human Services Dept). The idea is simple, if there is a critical mass of people in the population who are immune to a disease (whether due to natural infection or vaccine) these protected members (yellow) make it much less like that non-immune healthy people (blue) will get infected (because they are unlikely to contact an infectious person (red).
So to get Canada back on the road we will need a massive testing ramp-up (if we prefer quarantine of the sick to quarantine of society as a whole). As this happens we need to build herd immunity with vaccination and document that it exists. Vaccine development and expanded testing are exactly the type of innovative programs that fit with my plea that Canada go to the Moon (metaphorically) (see today’s blog).
Capacity in KGH and beyond: KGH continues to have good surge capacity (below). We are beginning to feel the effects of the Province’s decision to stop our discharge of patients (even if they are COVID-19-19) back to retirement homes and long term care facilities. Note that we still have 52 available ventilators and 169 available beds. My apologies to regular readers-we have changed the denominator to reflect entire bed capacity, rather than just funded bed capacity.
Today’s happy moment: It actually happened yesterday. Here is the Davies 4 team of amazing nurses and staff. Dr. Chris Smith, Michelle Matthews and I stopped by with a sweet treat to thank them for their great care for our mutual patients.