The evidence isn’t conclusive yet, but this is worth watching.

~2300 tests were reported yesterday from @UWVirology @UWMedicine. Positive rate seems stable. Lab running smoothly the first half of today with lots of results going out. Realtime tracker at https://t.co/81ED3b8zk5 pic.twitter.com/8VR32hFrne

— UW Virology (@UWVirology) March 18, 2020

The key finding there isn’t that there were fewer positives yesterday than the day before. We can’t know that for sure; at the moment, the data from yesterday includes around half as many tests as the day before so naturally we’d expect fewer positives. The key finding is that even if we assume that there were actually twice as many positives yesterday as the graph indicates, that would be roughly equal to the number of positives on Tuesday. In other words, we’re not seeing exponential growth.

The Seattle Times published this graph tracking infections in Washington state today:

Starting on February 28 and continuing all the way through March 14, in each period the new daily number is at least 50 percent greater than the previous total. But then, on March 16, it slows down slightly: Instead of 1,154 cases on March 18 (which is what we’d expect if the 769 cases on March 14 grew by 50 percent over two days), we see 1,012 cases instead. Yesterday’s number of 1,187 infections is an even lower percentage of the previous total, ALTHOUGH those numbers reflect the total only as of 4 p.m. Seattle time yesterday. The final daily number will doubtless end up bigger.

But it would have to end up a *lot* bigger than 1,187 to keep pace with the “previous day + 50 percent” rule. That would project to 1,518 infections by close of business yesterday. If it falls short of that, this will be circumstantial evidence that Washington state is indeed flattening the proverbial curve via mass social distancing efforts.

Which would make sense. They were the site of the first major outbreak in the U.S., at the Life Care Center nursing home. Washington was also the subject of that genomic analysis early this month that pointed strongly towards undetected community spread locally at a moment when most of the rest of the country was taking COVID-19 in stride. They were hunkered down and distancing themselves before most of the rest of us were. It stands to reason that their curve would be the first to flatten out.

Nate Silver is intrigued too:

Also, here are the daily numbers for King County, WA (Seattle), per @KCPubHealth:

3/8: 12
3/9: 33
3/10: 74
3/11: 44*
3/12: 36
3/13: 58
3/14: 60
3/15: 32
3/16: 68
3/17: 30
3/18: 44

* Having trouble tracking down 3/11 so the number is imputed based on the cumulative case count.

— Nate Silver (@NateSilver538) March 19, 2020

Major employers in Seattle were also well ahead of the rest of the country in asking employees to work from home. That both helps with social distancing and serves as a signal to people that it's not business-as-usual. https://t.co/QtbbeHKwt9

— Nate Silver (@NateSilver538) March 19, 2020

We’ll need more data to be sure but data will be plentiful soon as testing ramps up nationally. Meanwhile, Philip Klein asks the question on everyone’s mind: When does the “hunkering down” period end? We’re not going to shut down the economy until a vaccine is ready next year. We need a middle ground between holing up in bunkers and doing COVID-19 keg stands in Daytona.

In the wake of the Sept. 11 attacks, life went on in the United States. We just had to endure added inconveniences like taking off our shoes at airports and having our bags checked at sporting events. I think we need to get to the point where we think of this in a similar way.

That is, it’s possible we’ll consider temperature checks in airports, sporting events, and other crowded places. We’ll need to have more disinfecting of public areas. Maybe bars and restaurants are allowed to reopen but with much lower maximum capacity limitations. Some grocery stores have already adopted separate hours for those over 60, and maybe that practice gets extended to movie theaters, which then have to ramp up sanitation between showings.

Small-ball stuff like that will definitely happen, even without people being formally instructed to do it. Business owners won’t want their shops knows as infection pits, hubs of local outbreaks. They’ll likely insist on some physical distance between customers. Surgical masks will be commonly worn in public once they’re widely available again, which is good practice given the risk of infection by people who don’t know they have the disease. Temperature checks are already happening for reporters at the White House. Basic precautions will spread virally through the culture just as the virus itself spreads through the population.

What every scientist I’ve read this week seems to agree on, though, is that robust testing is the crucial step. It’s not a sufficient condition for a return to something approximating normalcy, but it’s absolutely necessary. Trevor Bedford, the Seattle researcher who detected the hidden community spread in his city earlier this month via genetic analysis, proposed these three steps last night, starting with “massive testing.”

This rollout of testing could be achieved through at home delivery of swabs with centralized lab-based processing combined with drive-through testing facilities. There are logistics involved in getting a result quickly, but it's really just logistics, which can be solved. 14/19

— Trevor Bedford (@trvrb) March 19, 2020

This strategy targets testing capacity at most likely cases and serves to detect exposure events early, when isolation is most valuable. This cell phone location based approach is outlined carefully here: https://t.co/cu09jbd6zB. 16/19

— Trevor Bedford (@trvrb) March 19, 2020

Individuals who have serological evidence of recovery and are no longer shedding virus can fully return to the workforce and keep society functioning (especially important for those at the clinical front lines). 18/19

— Trevor Bedford (@trvrb) March 19, 2020

Everlywell, a home testing company based in Texas, is already planning a home coronavirus test for the low, low price of, uh, $135. The sort of smart-tech surveillance that Bedford has in mind was the subject of two separate posts on this site yesterday. Scott Gottlieb has also been talking up serological treatments lately developed from the antibodies of people who’ve recovered from the disease in order to provide some temporary protection from infection for front-line health-care workers as they treat patients. If our bureaucracy can get its act together — and I have zero faith that it can — all of this is what the “new normal” will look like this fall, as we wait for the second wave of the disease and then a vaccine next year.

The part I have trouble grasping, though, is the “massive” testing regime. How does that work, exactly, when the disease is spread by people who are asymptomatic? Do you test randomly? Will large numbers of Americans agree to that? Mass testing would be easy if only symptomatic people passed on the virus; Americans could be asked to seek immediate free screening if they so much as sniffled. But if people are passing this on before they know they’re sick, it seems like the only option is to test them after they present symptoms and then try to work backwards and inform everyone they’ve been in contact with over the previous week that they were potentially exposed. Do authorities have the manpower to do that realistically?