I keep thinking about Lodi and Bergamo, two small cities in northern Italy both hit by coronavirus around Feb 23
Their infection rates looked identical for weeks, until, on March 8, Bergamo’s surged so rapidly that the military was later sent in to relieve overwhelmed morgues
Their infection rates looked identical for weeks, until, on March 8, Bergamo’s surged so rapidly that the military was later sent in to relieve overwhelmed morgues
What happened on March 8? Well, nothing. By then, both had similar policies in place, including social distancing.
The crucial moment was Feb 23, when the first cases appeared. Lodi immediately imposed social distancing interventions. Bergamo waited two weeks, until March 7.
In those weeks from 2/23 to 3/7, the two cities had near-identical case and transmission rates. Lodi’s harsh rules looked unsuccessful, even counterproductive – their case rate was rising right in tandem with Bergamo’s, where there were no such policies in place.
So why did Bergamo’s case and transmission rates surge *after* the city intervened, but not before? Why did Lodi’s intervention look useless for the first two weeks?
Over and over, we see a 7-to-14-day lag between when outbreaks actually occur and when they become apparent.
Over and over, we see a 7-to-14-day lag between when outbreaks actually occur and when they become apparent.
The time between when someone is infected and when they’re *recorded as infected* can get as high as two weeks. First it’s a 5-day incubation period, then a few days to begin taking symptoms seriously, then a wait for the test, then another wait for the results. Up to two weeks!
That two-week lag is a disaster. Uncontrolled, Covid-19 infections can double about every two days. That means, in two weeks, it can double 7 times — increasing by a factor of 128.
Think about it like looking at a faraway star. You’re actually seeing the star as it was millions of years ago, right?
Coronavirus can be like that. We’re often looking at, and responding to, infection numbers from two weeks ago. But that might be 1/128th of the reality.
Coronavirus can be like that. We’re often looking at, and responding to, infection numbers from two weeks ago. But that might be 1/128th of the reality.
That was what happened in Lodi and Bergamo. Lodi’s intervention took two weeks to register, during which time its actually-successful policies look failed. Bergamo waited to act until the *numbers* were bad, by which time the reality on the ground was catastrophic.
I keep thinking about Lodi and Bergamo when I look at the responses across the US today. In Virginia, for example, the numbers aren’t too bad but authorities are moving awfully slowly. Reminds you of Bergamo, doesn’t it?
