Last night I watched the Dateline special on the situation in Bergamo, Italy, where hospitals are overwhelmed. This morning I saw several posts on social media indicating that we were winning the battle by physical distancing. So I thought it would be useful to compare San Diego County and California with two places out of control – New York and Italy – and one place under control – S. Korea.
The data line for Italy is a bit deceptive because the outbreak there started about 2 weeks before New York, SD, and CA. On March 13, the first date on this chart, SD County had 10 cases, while Italy had 17,660. In other words, the crisis in Italy was at its midpoint then, while the US was just getting started.
Every locality but S. Korea has this in common: their daily change rates start incredibly high, as much as 70% to 80%, and as the outbreak grows, the rates tend to stabilize around 10% just before the peak. At the peak, which Italy reached around April 1, the rates drop to around 4%. New York is headed toward that now.
If we look at the change rates for SD County and California, there’s reason for optimism, but lots of reason to be cautious, too. SD County rates are around 12%, i.e., right where Italy was two weeks ago. Even with physical distancing, if there are a lot of undiagnosed cases, we still could be headed toward some rough times. If we don’t do the physical distancing, we pretty much guarantee things here will look like Italy in 2 to 4 weeks.
Now look at S. Korea, where the government took this seriously from the start and wasted no time testing and case tracking. The case count has risen slowly, but the daily change rate has been around 1% for the past month. This is what an organized, aggressive, serious response to the pandemic can achieve.