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The California curve

This Vox piece is a very interesting look at why the California “curve” seems to be flatter than we might have expected:

As the coronavirus started to spread in the US, California, not New York, might have seemed a likelier place for the pandemic to peak.

California, the nation’s most populous state, was among the first to report cases. The first possible case of community transmission in the US was reported in California on February 26; the state reported its first death on March 4. New York lagged by days, reporting its first community transmission case on March 3 and first death on March 14.

But just over a month after California’s first coronavirus death, as of April 8, the state has seen more than 17,000 cases and about 450 deaths — while New York state has more than 140,000 cases and about 5,500 deaths.

Experts say it’s too early to definitively say why California is faring so much better than New York. One factor, though, is that California simply acted more quickly than New York once it became clear that coronavirus was starting to spread in the US. If cases in California remain under control while those in New York soar — still a very big if — the experience could carry important lessons for how to deal with Covid-19, the disease caused by the SARS-CoV-2 coronavirus.

California’s experience likely reflects, at least in part, the value of quick, more proactive action — along the lines of what experts say is needed across the US, even in places that might not feel exposed to coronavirus right now. We “need to shift to a proactive mentality rather than reactive,” Krutika Kuppalli, an infectious diseases physician and emerging leader in biosecurity fellow at Johns Hopkins Center for Health Security, told me. The reactive mentality “has been very much the way this outbreak has been from the beginning.”

It’s also important, experts added, that California remains vigilant. With the huge economic harm caused by the coronavirus lockdowns, it can be tempting to ease off social distancing measures early. But to truly avoid a catastrophe like New York’s, experts say, California likely needs to stay at home as much as possible, at least until coronavirus cases appear to drop and proper testing and surveillance are in place to better track and mitigate new outbreak clusters.

Los Angeles County officials said as much, warning about a potential peak in the next two weeks. “If you have enough supplies in your home, this would be the week to skip shopping altogether,” Los Angeles County Public Health Director Barbara Ferrer said on Monday. “Without everyone taking every possible precaution, our numbers can start skyrocketing.”

There are other factors at play in the differences between the two states. One is the density of their largest cities: New York City is the densest city in the US (though San Francisco is second), and a lot of people packed closely together makes it easier for the coronavirus to spread.

New York state has also tested people at more than four times the rate of California, which could partly, though not mostly, explain the difference between both states’ reported cases and deaths.

A big factor — perhaps the biggest — is also chance. “There’s the possibility that there were just more introductions of the virus in the East Coast, in the New York area,” Jeffrey Martin, an epidemiologist at the University of California San Francisco, told me.

But California also acted more quickly than New York once it became clear that coronavirus was starting to spread in the US. The San Francisco Bay Area issued America’s first shelter-in-place order on March 16, and California Gov. Gavin Newsom issued a statewide stay-at-home order three days later.

New York, meanwhile, didn’t issue a statewide stay-at-home order until March 22. (New York City didn’t implement its own order beforehand; Gov. Andrew Cuomo said he didn’t believe it would work if only one city did it.)

And there’s evidence that social distancing was taken more seriously in some parts of California even before it was government-mandated. Restaurant data from OpenTable suggests that seated dining on March 1 was down 2 percent in New York City, but it was down 18 percent in San Francisco. (Though it was only down by 3 percent in Los Angeles, so not every place in California acted the same.)

As March began in New York, officials were encouraging people to go about their business. On March 2, New York City Mayor Bill de Blasio tweeted he was “encouraging New Yorkers to go on with your lives” and “get out on the town despite Coronavirus” — offering a movie recommendation for The Traitor. That did come before New York state confirmed a case of community transmission, but it also came after Cuomo, in a press conference with de Blasio, called community transmission “inevitable.”

Since I’m encouraging New Yorkers to go on with your lives + get out on the town despite Coronavirus, I thought I would offer some suggestions. Here’s the first: thru Thurs 3/5 go see “The Traitor” @FilmLinc. If “The Wire” was a true story + set in Italy, it would be this film.— Bill de Blasio (@BilldeBlasio) March 3, 2020

The same day, San Francisco Mayor London Breed, who had already declared a local state of emergency on February 25, warned the public to “prepare for possible disruption from an outbreak,” from dealing with school closures to caring for sick family members. California had confirmed a case of community transmission, in nearby Solano County, by then.

New York officials seemed to take the threat more seriously in the coming days and weeks, particularly after community transmission and deaths were confirmed.

The difference of a few weeks or days on public action and orders telling people to stay home may not seem like a huge deal. But it really is significant with the coronavirus, because the number of cases and deaths, especially early on in an outbreak, can double every few days if protective measures aren’t in place.

“With this virus, days, and even hours, matter,” Jen Kates, director of global health and HIV policy at the Kaiser Family Foundation, told me.

By March 23, three weeks after Breed and de Blasio’s tweets, New York state reported around 5,000 new coronavirus cases a day. California reported fewer than 500.

One of the big lessons from California: “Anytime you are dealing with an outbreak, if it appears like you overreacted, then you probably did the right thing,” Kuppalli said.

A lot of people thought the state and local governments were overreacting. But they weren’t.

It’s going to get more hairy here, I have no doubt. They’ve been preparing us for the peak coming in mid-April for a while. But they are not giving any happy talk about opening up prematurely. In fact, Governor Newsom and Mayor Garcetti keep saying June at the earliest and even then they aren’t prepared to just go back to normal. Newsom said he didn’t anticipate allowing the football stadiums to open in August.

The whole article is worth reading because it shows that people who were attuned to the historical precedents, like the 1918 pandemic, understood that initiating and keeping social distancing policies in place earlier enough to flatten the curve and do serious contact tracing was the key. That happened here and in other states. And some of the others like Florida and Georgia did the opposite. When all is said and done there will be a lot of lessons to be learned.

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