Friday, April 17, 2020

The Case for Staying Home - Now it gets hard

I’ve been tracking LA closely this week.  And, unfortunately, we’re not seeing the numbers we want to see.

We are now entering the time when people’s patience for staying indoors is wearing thin.  Protests are happening demanding that we open everything up again.  Disgusting displays, including blocking an ambulance in Michigan, and protests here in Huntington Beach (“Liberate Huntington Beach”, echoing the inflammatory rhetoric of Trump) are starting to happen.  House parties are still going.

And yet, in theory, if nobody came near anybody for a period of two weeks, we’d see new cases crash to zero.  But that’s not happening.  And, it’s not happening because people don’t understand what’s happening, and they feel that social distancing doesn’t apply to them.  We aren’t doing enough - and we certainly can’t afford to slide backwards.

I was quite excited earlier this week.  It really looked liked LA would hit zero new cases before the end of April.  We’d then monitor to keep those cases at zero, and then we’d be done.  I was looking forward to celebrating that event.

That day is looking further and further away.  Today it was announced that in the last 24 hours we reached 11,391 confirmed cases in LA County, and added another 537 new cases - that’s where we were April 3.  At the rate we’re falling, instead of hitting zero new cases by the end of April, we’re now looking at the third week of May (assuming that there isn’t yet another resurgence from people gathering around Easter).  I’m hopeful that with each passing day people treat this with more seriousness, not less.  We need to to get through this.  We must maintain the strength to get through this - by supporting ourselves and supporting each other. 

We have avoided the nightmare of New York, but if you look, Florida just had more new cases in one day than ever before.  The US refuses to peak and decline as regional infection zones begin to grow (we reached over 700,000 cases here in the US today).  Italy, while declining, is doing so at a snails pace and isn’t likely to hit zero new cases until late May, and now we’re seeing Canada backtrack and start to ramp up a second peak. 

This is the cost of complacency.

I also want things to get back to the way they used to be.  But in order for that to happen, we need this number to be zero.  Then, we need this number to stay zero until we are sure that there are no lingering cases.  We need this to happen as quickly as possible.  And it’s not happening fast enough.

All data from Johns Hopkins:

Wednesday, April 15, 2020

The Case for Staying Home - LA's speedbump

Monday afternoon looked really good for LA.  We reported only 228 new cases, the lowest seen since we hit our peak.  At this rate, we were on track to be zero new cases by April 23 - just 10 days later.

Then yesterday happened and we hit a spike of 627 new cases, which was almost near our previous peak of 711.  Today it came down again with only 449 new cases, but this has pushed the "zero new cases" date into early May.

Now, LA has only 10m people, so the data is going to be much jumpier than when looking at a whole state or country, but I must admit I had allowed myself to get excited by Monday's numbers.  Nevertheless, I'm hoping that we drop back to the levels we were at before.

However, it's been my observation that people are starting to take this less seriously than before.  There's a dual feeling of "this can't continue, so we just need to get out", and "nothing has really happened, so there's no big deal about getting back outside".  If that is the attitude of the population at large, this curve will take a long time to reach zero, or could simply flare back up again.  Now is not the time to be complacent.

Perhaps we shouldn't be surprised.  I had been hoping that LA was doing better, but if we look at Italy, they also are on track for reaching zero new cases in the first week of May as well.  If Easter weekend also created a surge, we won't see that until late next week.  Let's hope people continue to take this seriously, otherwise, it's even longer before we can return to normal.

Thursday, April 09, 2020

The Case for Staying Home - The End of the Beginning

Winston Churchill, 1942

Now this is not the end.

It is not even the beginning of the end.

But it is, perhaps, the end of the beginning.

There are a couple of very important milestones to consider when we think of getting through this Covid-19 crisis.

1) The day that the number of new daily cases peaks, and each day after that we have fewer new cases than the day before.
2) The day that the number of new cases reaches zero.
3) The day that the number of existing cases reaches zero.
4) The day that we are confident that the number of asymptomatic carriers reaches zero.

For Los Angeles, Italy, Australia, and a bunch of other places, we have passed the first milestone.  We are truly at the end of the beginning.  Now, we need to see how quickly we reach the beginning of the end.

The reason that I'm mentioning this, by the way, is that I've seen a number of different reports that talk about a given location "peaking".  Yet, without context, we don't know what peak is being referred to.  The Institute for Health Metrics and Evaluation (IHME) has a brilliant set of analysis, where they talk about "peak hospital resources use" and "peak deaths".  These are both incredibly important metrics, but not what I'm discussing.

Last time I put up a graph which showed the peak of new cases for Italy.  I showed that Italy peaked on March 24, exactly 14 days after their March 10 stay at home order.  However, at the time, we didn't know how Italy's decline would look.  Now we do (apologies for the formatting - I wanted this to be legible):

We can see here that Italy is dropping at a steady rate of roughly 120 fewer new cases each day than the day before.  This doesn't mean that Italy is curing people at the rate of 120 people a day.  It means that, on April 9, Italy had 4204 new cases in the prior 24 hours.  Therefore, on April 10 (tomorrow), they will have only 4084 new cases in the previous 24 hours.  Because of the bounciness of the curve, this exact number is unlikely, but the trend is reasonably good.  If this continues linearly (and I really don't know if that's likely, or if it is set to accelerate or decelerate) then we can predict the day that Italy hits zero new cases.  Currently, that day is May 14 (Edit: with the original figure, this was April 30).  We can also predict the final number of infected, which would be 215,166 (Italy currently has 143,626 (again, all data from Johns Hopkins).  So, even though Italy is past their peak, over 60,000 more people are expected to contract the virus  before they finally get through this first wave (I'll talk more about subsequent waves later).

Given that I live in Los Angeles, I've been tracking LA with specific interest.  I had been hoping to see that we would demonstrate the same peak as Italy.  It took a few days to verify it, but since LA shut down on March 19, we should have seen our peak on April 2.  It looks like we could say it actually happened on April 3.  And, like Italy, there is now enough data to make an early prediction on the rate of decline (and, like Italy, I'm speculating that this decline is linear and I don't know if it will be).  Based on the last week, it looks like LA's new cases are declining at a rate of 21 fewer new cases/day (interesting fact, if we were to decline at the same rate as all of Italy, adjusted for population, that would be 20 fewer new cases/day - so we are seeing an extremely similar type of response).  Based on this projection, Los Angeles county will see zero new cases on April 29 with a total infected count of 12,045.  As of April 9 we are at 7955, so, like Italy, we still have about 1/3 of the way to go, and over 4000 people will become confirmed cases before the end of April.

However, this is all good news.  I think we can safely say that we are past milestone #1.  Now, the US as a whole is in much worse shape and I will continue to track the many states that are just beginning their infection ramp.

So, if this the end of the beginning, what is the beginning of the end?  There are two.  The first is a period after the zeroth new case.  If we assume that it takes 14 days to present possible symptoms, then we would want to see at least 14 days of zero new cases (ideally, much longer).  We want to make sure that all lingering infections have run their course before we lift social distancing measures.  Mayor Garcetti here in LA talked about us staying indoors until the end of May, and based on these numbers, that seems like the right plan.

The second "beginning of the end" is actually the next 12-18 months.  Until a vaccine is discovered and widely deployed, or herd immunity is reached, there will inevitably be flareups.  And, then, unless we act differently, we'll be scurrying back into our houses for another 3 months all over again.  Additionally, because, at least in the US, we have such a large population of states that are treating this virus with widely different levels of seriousness (from "adult and listen to the science" to "childish and criminal" a la Mayor Vaughn of Amity in the movie Jaws) we will have a secondary explosion just from people traveling within the country from one state to another.

So, the solution is twofold.  First, we must do like Germany, and implement widespread national testing for antibodies (I had a link here to FT, but it seems to only work if you go via Google).  This will allow us to know who is immune, and how widespread our herd immunity already is.  This allows us to get the economy restarted.  Second, we must do it right this time (like South Korea) and implement testing and case tracking and isolation to quickly pounce on flareups to allow us to stop the fire before we end up with another inferno.  This period will likely see social norms of continued mask-wearing and fist-bumps, rather than handshakes, well into 2021.  Remember that the Spanish flu of 2018/2019 had three severe waves.

So, we are not at the beginning of the end.  We likely are only 1/3 of the way through our quarantine and we must not relax our efforts to isolate (and we must have the utmost sympathy for the horrors to be witnessed by states that are have only recently entered their quarantine).  But, like Churchill said, we are likely at the end of the beginning.  And there is real comfort in that.