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The difference a week makes

Imposing a stay-at-home order sooner rather than later ha a profound effect on how many people come down with coronavirus.

The person-to-person spread of the coronavirus in the Houston region would peak in two weeks and burn out by mid-May if the stay-at-home order invoked Tuesday is continued until then, according to modeling by local scientists.

The modeling, which informed Harris County Judge Lina Hidalgo’s order, considered the effect on the spread of COVID-19, the illness caused by the virus, if she’d taken the stringent intervention immediately or waited a week or two weeks to act. Spread would increase exponentially had she waited, it found.

“From our modeling, it was clear that waiting is not a good thing,” said Eric Boerwinkle, dean of the University of Texas School of Public Health, who conducted the study with a biostatistician at that Houston institution. “The numbers are sobering, but the message is clear: early intervention is better than late intervention and more stringent intervention is better than less stringent.”

UTHealth released the modeling data as the city of Houston began gearing up — scouting sites that easily can be converted into medical centers, looking for hotel rooms for COVID-19 patients who cannot isolate at home or in a hospital — for what’s expected to be the next, worse phase of the pandemic: the exponential increase in disease numbers.

[…]

The UTHealth modeling, shared with city and county officials Monday, provided data backing the warnings. It found that intervening immediately would limit the number of cases in the region to a peak at about 150 a day around April 7 and stop the spread around May 12. In that time, the cumulative total of cases would reach nearly 3,500, it found.

Cases would peak at more than 1,000 a day on April 15 if Hidalgo had waited a week and more than 6,600 a day on April 22 if she’d waited two weeks. Transmission would last until May 29 under the first scenario and June 16 under the second.

All three of the scenarios are based on the premise the restrictions would continue until mid-May. Hidalgo’s order is scheduled to expire April 3.

This is what “exponential growth” means. The basic idea is that if everyone is out there living their normal lives, anyone who has coronavirus – remember, it takes about a week for people to become symptomatic, so you can be walking around for quite some time not knowing you have it, infecting people wherever you go – will be spreading the disease to a larger number of people, who will then do the same thing, than if everyone were at home where they will encounter far fewer people. This is one of the reasons why South Korea was as successful as it was at stopping the spread in that country – they jumped on this kind of action right away. (They also did a crapload of testing and were able to aggressively track people’s movements, but never mind that for now.) For that matter, look at the difference between Kentucky and Tennessee. Which outcome would you prefer?

Point is, putting the stay-at-home restrictions in place now, or even later, after the disease has had time to spread even if the known number of infections is still low, would mean we’ve given it an unfettered head start. That’s the scenario we need to avoid, and it’s the reason why the death wish cultists aren’t just wrong, they’re deeply dangerous. Listen to the experts. The fondest hope we have right now is that in a few weeks, when we can think about beginning to go back to normal, we can say it wasn’t nearly as bad as it could have been. We have a chance for that now.

UPDATE: Read this. Look at the chart. Consider this excerpt: “It means that on average, every infected person infects three other people, not 2.5 other people—which makes the spread of the virus much wider and faster. Without any control measures, for example, it means that after ten generations a single person will be responsible for 80,000 infections instead of 10,000 infections.” That’s what we’re talking about here.

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6 Comments

  1. Flypusher says:

    The call to shut down the rodeo looks better and better.

  2. Jason Hochman says:

    It needs only rudimentary knowledge of viruses to know that avoiding contact as much as possible, is avoiding the virus as much as possible. But I have many questions. I did read the UT Health modelling, but there are some things that don’t make sense to me.

    For example, the Lancet article about the first known domestic transition, which was a woman who came back from China with the virus. She passed it on to her husband, who lives in the same house. But nearly 400 contacts with this couple did not have one positive test. So, how do we know that every case causes three new cases. And, a Columbia University study determined that most of the transmission in China was from asymptomatic carriers. That says that each sick person is not infecting three others, but rather, that there are a lot of people who don’t know they have it, because they either develop no symptoms, or have such mild symptoms that they may think they have a little bit of allergies, or ate the wrong thing, or just stressed out and tired. To me, the key is to test aggressively–why test the visibly ill–treat them as if they have the virus. Tell them to quarantine at home until better, or, if they are seriously ill, hospitalize them. Then test everyone else.

    I also wonder why, when the virus first came to the US in mid January, it did almost nothing for two months, in spite of the federal government ignoring and minimizing the risks. Well, the executive, anyhow. The press had few stories about the situation. Italy had a crisis, and the virus couldn’t have arrived there much sooner than it came to the US. Then, suddenly it started spreading exponentially, threatening to overwhelm the healthcare system. Why? According to the Global Health Index, the US is the most prepared nation in the world. Perhaps the federal government has more resources available but is not using them.

    The stay at home order really didn’t change much from the way things had been since the 16th when restaurants went to take out only and bars shut down. Hopefully the stay at home order emphasizes to everyone the importance of maintaining a distance and limiting contacts as much as possible.

  3. Wolfgang says:

    Re: “The stay at home order really didn’t change much from the way things had been since the 16th when restaurants went to take out only and bars shut down.”

    This is actually something that can be measured empirically pretty well, and without much effort: With cell phone activity data. The Houston Chronicle has already published a graph based on this aggregate-level data.

    Note that this is not the same thing as being used in Israel, which has move to use individual-level cell phone data in conjunction with surveillance camera video for contact-tracing of confirmed cases (incl warnings sent to those who came in contact with identified virus carrier), and to enforce quarantines of the infected. The original rationale for the surveillance capability was to security (terrorism). Now it’s being re-purposed to fight the pandemic.

    https://techcrunch.com/2020/03/18/israel-passes-emergency-law-to-use-mobile-data-for-covid-19-contact-tracing/
    https://www.businessinsider.com/coronavirus-israel-government-track-patients-quarantine-2020-3

    It’s also being discussed in Europe, but a very sensitive issue because of the civil liberties personal-data-protection implications. (Europe is stronger on protecting data privacy than US). One proposal is to authorize this intrusive sort of state surveillance with a pre-set expiration date, so that the practice will not continue after the pandemic is over. And there are, of course, democratic controls in European democracies. Israel, however, is politically fractured and undergoing a constitutional crisis at the same time it is facing the pandemic.

    Authorities in Poland are already using a smart-phone app to check on and enforce compliance by those sent into self-quarantine.

  4. brad says:

    Jason,

    Regarding the comment “According to the Global Health Index, the US is the most prepared nation in the world.”…..

    Well, we can have the most prepared fire department in the world, but if the firemen sit on their butts when the 911 call comes for a house on fire, and they don’t suit up, and they don’t drive their firetrucks to the scene of the emergency, and they wait until the fire is a 5 alarm multiple homes fire throughout the neighborhood, then it isn’t much use to be the most prepared.

  5. Jason Hochman says:

    brad, that is what I meant by the sentence about the federal government is maybe not using all of its resources. And waiting too long to use them, because “it makes the numbers look worse.”

  6. […] previous projection done by UT Health scientists suggested that the Houston area could peak in mid-April, with the […]