A few years ago on Quora, someone asked me what the odds were that devastating global pandemic like the Spanish Flu would occur. My response was that it wasn’t very likely, and that’s borne out by the remarkably low global death rate from COVID-19.
Why did they ask me? I helped build the most sophisticated vaccination, communicable disease and outbreak management automated solution in the world in the 2000s. In the aftermath of SARS, the Canadian Naylor Commission made six recommendations, one of which was to automate data capture, contact tracing and case sharing. The global technology firm I was with won that contract and I helped deliver the solution, leading business architecture, driving a substantial architectural transformation of the solution and owning key portions such as healthcare messaging. Panorama is now in use in much of Canada and in other parts of the world as well, and data from it is being used to help with various jurisdictions’ responses to COVID-19.
SARS vs the Spanish Flu
It’s worth starting out with an example of what a disease is up against. The SARS epidemic of 2003 compared to the Spanish Flu epidemic of 1918 is very instructive.
- SARS was more infectious and deadly than the Spanish Flu. SARS occurred in a much, much more globally interconnected world with infected people getting on jets and landing on the other side of the globe hours later. Spanish Flu occurred in a world without passenger planes.
- SARS killed fewer than 1000 people world-wide (916). The Spanish Flu killed as many at 50 million people.
- The SARS epidemic killed 0.000013% of the global human population. The Spanish Flu killed 3% of the global human population.
- The SARS epidemic lasted seven months from beginning to end. The Spanish Flu lasted two years.
- The SARS epidemic killed an extraordinary number of health care workers compared to the general populace. The Spanish Flu was much more weighted to the general populace.
In short, a vastly more deadly disease was contained in a much shorter time with a tiny percentage of the casualties through the amazing workings of our world-wide public health system. The average person had virtually no chance of getting it.
Our public health system world-wide is exceptional and under-appreciated. For something to overwhelm it so that 3% of the world’s population died would be off-the-charts unlikely, so unlikely that I would be looking at War of the Worlds explanations before I believed it to be true.
In the above example, the World Health Organization (WHO) took or was granted coordinative control of outbreak management by the vast majority of jurisdictions for world-wide information dissemination.
Each country had a national body which engaged directly with WHO and local efforts. (There was tremendous back-and-forth on this in Canada, as the vast majority of cases were in downtown Toronto, so it was quite reasonable for Ontario’s public health organization to have direct responsibility.)
In general, health jurisdictions within each country established their own outbreak management teams. For example, in British Columbia, this fell to the BC Center for Disease Control.
Public and Acute Health Practitioners — highly trained, highly credentialed, front-line experts — were of course in the forefront of the effort, identifying cases and establishing protocols.
There were several tactics used in the fight against SARS:
- Quarantine — individuals who were exposed but were not yet sick were separated from people who weren’t exposed, usually in medical facilities but often in their homes
- Isolation — individuals who were already ill were separated from those not already ill in medical facilities
- Interventions — These ranged across the spectrum from the individual to the global. The largest was WHO world-wide travel advisories. These travel advisories took billions out of the world’s economy, around $1 billion from Toronto and Ontario alone. The smallest were treatments which had been proven successful in reducing the severity of the illness and preventing death.
- Sequencing of the Virus — Determining the genetic heritage and markers of the disease allowed more effective testing, separating those with SARS from those expressing symptoms similar to SARS but not caused by it. l4]
What could get past this highly evolved system of protection?
So what are the characteristics of a disease that could successfully bypass the extraordinary system of communicable disease prevention and wipe out half the population of the earth?
- Much more infectious than SARS — Measles is 5–6 times as infectious as SARS, which typically only saw three people infected by each infected person. A higher rate of infection would spread the disease much more widely much more quickly.
- Similar vectors but longer lasting than SARS — SARS was spread dominantly by airborne vectors through sneezing, but the virus also lingered on surfaces and there were many cases that occurred due to contact with a surface containing the virus. SARS can last for hours on surfaces and days in human waste. If that were days and weeks, many more people would be infected by every surface that any SARS suffered sneezed upon, and likely a billion could have been infected by human waste in parts of the world with poor sanitation.
- Much longer incubation period than SARS with infectiousness — SARS had an incubation period of 10 days, meaning that less than two weeks after exposure a person would be exhibiting full-blown symptoms. A longer incubation period would allow infected people to transmit the disease much more broadly before being isolated. Notably, one group of SARS patients had a much longer incubation period.
- Much less severe initial symptoms than SARS — SARS was very debilitating quickly, and typically patients died after weeks of illness. A slower onset of symptoms would allow the infected to avoid isolation for much longer and infect many more people.
- Much higher eventual lethality than SARS — SARS had an overall fatality rate of 14–15% of those infected, skewing heavily to the very old, the very young and the previously ill. To kill 3% of the human population despite attempts to treat the illness, untreated lethality would have to approach 100%.
- Same starting point as SARS — SARS originated in China. A disease with the characteristics above could spread worldwide through manufactured goods.
- Greater resistance to heat and disinfectants than SARS — Common disinfectants and temperatures of only 56 degrees Celsius will degrade the SARS virus to the point where it cannot infect others. Higher resistance to both heat and common disinfectants would prevent sterilization.
A disease with the above characteristics would spread much more rapidly and include consumer goods and produce from China as a key vector of the spread of disease in addition to infected individuals. This would rapidly spread to other manufacturing centers.
It is possible that a disease with the above characteristics could cause a global pandemic that wipes out half the world’s population, overcoming all of the extraordinary public health and communicable disease surveillance measures the world and countries have in place.
How does COVID-19 compare?
Comparing and contrasting to COVID-19 against these characteristics and attributes, we see the following.
- COVID-19 is roughly as infectious as SARS.
- COVID-19 has similar vectors of similar duration to SARS.
- COVID-19 has an incubation period roughly the same as SARS.
- COVID-19 has many more people who are asymptomatic, and spread the disease as a result.
- COVID-19 is much less lethal than SARS.
- COVID-19 did start in China, but has not transmissibility from shipped goods, so this is moot.
- COVID-19 is about as easy to eliminate on surfaces with disinfectants as SARS.
Looking at the above, we see that the major difference is point 4. It spreads more because many people don’t realize that they are sick with it. Among other things, that’s why physical distancing and wearing a mask are important, not because they keep you safe but because you might be a carrier and not know it. Distancing and masking break the chain of infection.
It was easier to lock down SARS because it was easy to spot carriers. They were sick. That’s why so many hospital staff died, as they were treating the sufferers. A great deal of good work was done on vaccines for SARS, but they proved unnecessary due to the rest of the public health response and they were never brought to completion. Part of the reason we have vaccine candidates starting trials is because researchers were able to start from the work done on SARS in many cases. Another part of the reason is that we have extraordinary tools for sequencing genomes and synthesizing vaccines that are broadly today, and weren’t in 2003.
The asymptomatic nature and the global spread does mean that we’ll see two years of SARS. It will be more like the Spanish Flu in that regard. And we don’t have guarantees yet that immunity is granted by having had the disease once. And we don’t have guarantees that any of the seven or so vaccine candidates will provide statistically valuable reductions in transmission or severity. We will be going through regional periods of distancing likely through the end of 2021.
But 3% of the world’s population is 230 million people. We are flattening the curve on COVID-19 and are three orders of magnitude under that as of the time of writing this article, about 360,000 people. It’s sad, tragic and we should care about every person who suffers and dies unnecessarily due to poor public health responses in countries like the USA, but we are so far off of the scale of death of the Spanish Flu in both relative and absolute terms that we are nowhere near that territory.
But to be clear, in the past 20 years, we’ve had global public health responses to SARS, Ebola, H1N1 and COVID-19. Global epidemics requiring globally and nationally coordinated responses are a fact of life. In many ways, we were lucky with Ebola and H1N1. COVID-19 has been the worst of the four. But it was just a matter of time. And it’s just a matter of time until a disease with similar characteristics turns into a pandemic.
I’d say hug the next public health nurse, doctor, epidemiologist or administrator you see, but don’t. Just thank them from 2 meters distance and wear a mask when you are in places with lots of people.