Sunday, February 20, 2005

simulated smallpox and calling in sick

The March 2005 issue of Scientific American (available at a grocery store magazine rack near you) has a fascinating article, "If Smallpox Strikes Portland" by Chris Barrett, Stephen Eubank, and James Smith, on some work they did with simulating the spread of disease in a very realistically modeled city. They model the actual geography of the city, use census data to model its population, and track people moving around in a way that looks a lot like the sort of finite element analysis weather prediction models use. Then, they drop in a virtual disease like smallpox or flu, and see how it spread given different ways of responding to it.

Anyway, the results are what grabbed my attention. The two most important factors for controlling the spread of disease turned out to be

1. whether or not contagous people stayed home, and

2. how quickly the government responded to the outbreak.

Not whether they used vaccines or quarantines, or whether it was massive vaccination or targeted vaccination, just whether people went home when they got sick and how quickly the government responded.

Let's ponder that first factor for a moment.

I listed those factors in order of impact, so people staying home when they felt sick (when the symptoms first stated to appear, at which point they became contagous) had the strongest impact on disease spread.

Now, consider the policies where you work. Do they encourage sick people to come in or stay home? At one previous job, we had a single pool of "personal days", no separate sick and vacation days. Net result: you wanted to use all those days for vacation, so you came in even when you were feeling marginally sick, i.e. when the symptoms first started appearing but hadn't gotten strong yet.

If you're someone in charge of writing those policies, it might be good to think about disease spread and productivity. You're dealing with a population -- employees -- and this study suggests that the best way to spread disease through a population is to get contagous people to spend more time in the population. So, the question is whether it's better to take the productivity hit from encouraging contagous people to stay home, or from having them come in and getting wider spread of the disease. Sorry, I don't have a right answer for you, but it's definitely worth thinking about.

2 comments:

Asya said...

What you forget to mention is that the company you worked for also allowed people to work from home.

So if you were sick, but not so sick that you couldn't work, you worked from home to prevent spreading the germs.

False Data said...

That was the theory for a couple of the companies. In practice, a fair number of people came in anyway. Consider management, sales, marketing, and administrative staff, for example: they're often more productive in the office rather than at home.