Future Pandemics—Today (Part 1)
Part 1: Failure of Containment
I’ve been compiling a list of topics to write about on this blog for the last nine months, a to do list that’s grown so long that it now exceeds my capacity to complete them in an efficient manner. One idea about the future of medicine that I’ve been meaning to get to is the topic at hand, future pandemics, but I wasn’t sure how to approach the issue. Should I begin with a cursory review of one of the worst pandemics in history, the 1918 H1N1 flu that killed 50 million people worldwide, and segue into conjecture about what factors could make such an event easily happen again? Or should I tackle the “known unknowns” about what sort of organism might cause the event, what part of the globe it would likely come from, and what sort of damage it would do to people’s health and well-being? Alternatively, I could paint the worst-case scenario: the death of a sizable portion of humanity and the ensuing collapse of social, moral, and economic order.
Sometimes the future is written about years, even decades in advance with such precision that it would seem as if the author has a very special Delorean in his garage that no one knows about. (I’m thinking of The Age of Spiritual Machines here). And sometimes the future sends a letter to itself today. The news today has arrived quicker than I had time to write my post. The future is writing itself.
I’m speaking, of course, of COVID-19, the disease caused by the new Coronavirus SARS-CoV-2. The CDC announced this week that the virus, which the world first learned about in December, is likely to spread to America. And when it spreads, it will be rapid and it will be deadly. Why? It’s because many carriers of the virus are asymptomatic and the case fatality rate is low.
It’s counterintuitive, but a deadlier infectious organism often kills less people overall owing to the simple fact that symptoms are not subtle and the ill, confined to homes and hospitals, assuming adequate infection control measures, are not able to spread the disease widely. The recent Ebola outbreaks are a great example of this. If you got Ebola virus, it wasn’t subtle. You were febrile, vomiting, and having massive amounts of diarrhea. The case fatality rate was around 50% which was terrible for individual patients, but it meant that the epidemic didn’t have a chance to spread globally in a significant way once containment measures proved successful.
Previous outbreaks of novel strains of Coronavirus had much higher case fatality rates than the current strain, which seems to be killing about 2-3% of patients that get infected. That’s worse than the seasonal flu, but better than MERS or the first SARS outbreak. But since many more people with the virus may be asymptomatic carriers that are not and will not be tested, the case fatality rate might actually be lower (due to a lower denominator).
What’s interesting today about the virus is that the global health community may have reached the assessment that global containment of this new corona virus is no longer possible. A pandemic is upon us. Since there’s such a low case fatality rate and because transmission appears to occur from asymptomatic hosts, we need to start preparing for COVID-19 to become a common cause of respiratory failure from infectious pneumonia.
Now for some back of the envelope calculations. We’ve all probably gotten one or more of the four common corona viruses that usually infects humans. It didn’t kill you, but it made you miserable. It’s one of the most frequent causes of the common cold. Now, let’s assume the new deadly corona virus, SARS-CoV-2, infects just as many people as the common cold. To be conservative, I’ll guess that 25% of human beings get infected with it over the course of the next few years and that the case fatality rate remains at 2%.
Forty million people will die.
That’s a worst-case scenario, but that’s the kind of prognosticating we need to do with a pandemic (it’s no longer an epidemic) of this scale. The WHO estimates that up to 650,000 people die of the flu virus each year. The number of deaths I am estimating from SARS-CoV-2 pales in comparison. This is a devastating number to fathom. But we must think of this worst case scenario because it is clear now that: 1/ the virus was not successfully contained, 2/ the virus is carried and transmitted by asymptomatic hosts, 3/ the case fatality rate may be as high as 2%. That 2% doesn’t sound like a big number, but two percent of a quarter of humanity equals a virus that can be as deadly as the 1918 flu. What it will do to individuals and societies will be the topic of my next post. But keep that worst case scenario number in mind. Not to panic, not merely to pray. But to prepare.
Forty million dead.
Before I leave you sleepless tonight, let me offer a better-case scenario. I still must assume that the virus is pandemic, but the case fatality rate is lower, let’s say one-tenth my estimation, and that only one out of ten people gets infected. That will still mean 1.5 million people die of this virus. If it becomes as episodic and reliable as the flu, that could be soon be the yearly death toll, which means we may have to accept the reality of a new lethal lung infection for which there is currently no cure.