The Week of the Virus

Michael - Thursday

This has been the Week of the Virus on MIE. Since Caro’s post last Friday, all but two blogs have been focused around it. Yesterday Sujata posted a timely and helpful piece about friendly “social distancing” as a way of reducing the spread of COVID-19 (or the novel coronavirus as the media still prefer to call it). Caro did a similarly valuable piece last Friday. So I thought I’d close out the seven days with my two cents worth.

I must admit that initially I was pretty sceptical about the fraught reactions and stock market panic, but now I accept that I was somewhat missing the point. I have to say that every health care professional I’ve spoken to tells me that they see no real hope of containing the virus. The way our modern world works, people move too quickly and too widely for a disease to die out of its own accord. Yesterday, Angela Merkel estimated that between 60% and 70% of Germans could contract the disease. Two members of the company I work with in Johannesburg just discovered that a big convention they attended in Toronto had (at least) one infected delegate. They are already in other parts of the world. I’m not sure if any countries remain free of the virus today, but unless they close their borders and allow no one in, they will have cases. 

In a way, it’s all very similar to the pandemic of the H1N1 strain of 2009. Although the initial infection was pinpointed to only a few people from Mexico, by the time their contacts were traced it was too late. The disease had spread widely. At the same stage of its career as COVID-19 is at now, there were less infections than we currently know of for COVID-19. After a while H1N1 started to climb rapidly and eventually it infected over 60 million people in the US, but the number of deaths was only some 12,500. However, across the world it’s estimated that over 500,000 people died from the 2009 flu epidemic. And that’s not out of line for annual flu deaths. So what’s different with COVID-19?

The main one is the seriousness of the disease. H1N1 wasn’t fun—I caught it from a road trip with a friend of mine who's a doctor—but it felt like a really bad case of flu. With COVID-19, especially older people may become very sick. Some of them die, but the death rate is still very low. The issue is not whether the disease will spread or not (it will), but how fast it spreads.

Projections of exponential growth in Europe

In a previous life, I worked as an applied mathematician and was involved with mathematical population modelling. By modelling we mean computer simulations and mathematical equations that try to explain the behaviour of how population size evolves. Such models are too general to give predictions of what will happen, but rather indicate how it will happen. For epidemics, the model is quite simple but surprisingly realistic. It assumes that the rate of increase of the disease is proportional to the number of contacts between susceptible and infectious people. (This is modelled as the number of currently sick people multiplied by the number who are not currently infected or have recovered or died. But we don’t need to worry about the details here.) The important thing is that this model leads to so called exponential spread of the disease. That means that it grows slowly at first and then faster, and then very, very, fast indeed until essentially everyone has been infected. The big concern is that when we reach the very, very, fast stage, the health care system won’t be able to cope. The problem is not that a huge number of people will die from COVID-19, but that the flood of additional patients will make it impossible for hospitals and doctors to deal with other serious emergencies properly. Here we’re thinking of first world countries; third world countries’ health systems will have no hope at all. So people will die of COVID-19, but more will die (unnecessarily) of pneumonia, heart attacks, complications of other flus, strokes, and so on. So slowing down the spread is really vital. As one commentator put it, "If you're really ill, would you rather be treated in the intensive care unit or the hospital parking lot?"

And, of course, the light at the end of the tunnel is a vaccine. (Yes, they do work. No, they don’t cause autism.) That’s more than a year out, but if we can keep the growth rate down, then most people never will contract COVID-19.

So take a look at what Caro and Sujata said we can all do. 

Excuse me now while I wash my hands...