"Lockdowns work against coronavirus. But they take a few weeks to show theyre working."
https://www.vox.com/future-perfect/2020/3/26/21191702/coronavirus-lockdowns-stay-home-new-cases
Experience from other countries
On January 23, China locked down the city of Wuhan amid a growing epidemic. On that date, the country had 830 cases. Much of the rest of Hubei province locked down later that week, and then restrictions were imposed on the whole country.
For the next few weeks, things got worse. By February 13, the country had 63,851 cases - most of them in Wuhan's Hubei province. But things were starting to turn around. That day, China reported 5,090 new cases - more than on any previous day (except the day of a one-time change in the types of cases reported). On February 14, however, officials reported 2,641 new cases. On the 15th, 2,008. New case numbers kept declining from there; China now reports no new local transmission cases (though they could be either missing some or hiding some, experts don't think they're hiding a full-blown epidemic.)
Take a look at that gap again: The peak of new cases came fully three weeks after the lockdown started. In Italy, it's starting to look like the same dynamic is at work.
"These big social distancing measures take time to work," Johns Hopkins Center for Health Security director Tom Inglesby tweeted Monday. "The impact of big interventions in Wuhan China took about 3 wks to start to reverse things. And then everyday after the situation got better."
Should the US expect the same thing?
Not necessarily. Some things are definitely different. The US implemented social distancing measures more gradually than Wuhan, which escalated quickly from few restrictions to a full lockdown. No place in the US is employing measures as strict as Wuhan's. China separated symptomatic people from their families, and locked people in their houses. Enforcement of stay-at-home orders has, so far, been lax in the US.
But if our measures suffice to reduce transmission so that each new patient infects less than one person, it wouldn't be surprising if the overall trajectory of the disease in a city like New York looks somewhat like China's, with cases peaking three weeks after the measures went into place. That would put us into early April.
In other parts of the country, where those measures haven't yet been put into place, the peak is even farther off. |