In most major countries, daily case growth has switched from exponential to linear, an important first step towards the infection being under control. See https://ourworldindata.org/grapher/daily-covid-cases-3-day-average for more, you can change which countries are on the graph for more detail. The growth rate in the world as a whole has also turned linear, https://ourworldindata.org/grapher/daily-covid-cases-3-day-average?country=USA+CHN+KOR+ITA+ESP+DEU+GBR+IRN+OWID_WRL . Since this is growth per day, a horizontal line represents a linear growth rate.

If it was just one country, I would worry it was an artifact of reduced testing. Given almost every country at once, I say it's real.

The time course doesn't really match lockdowns, which were instituted at different times in different countries anyway. Sweden and Brazil, which are infamous for not taking any real coordinated efforts to stop the epidemic, are showing some of the same positive signs as everyone else - see https://ourworldindata.org/grapher/daily-covid-cases-3-day-average?country=BRA+SWE - though the graph is a little hard to interpret.

My guess is that this represents increased awareness of social distancing and increased taking-things-seriously starting about two weeks ago, and that this happened everywhere at once because it was more of a media phenomenon than a political one, and the media everywhere reads the media everywhere else and can coordinate on the same narrative quickly.

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I've been forecasting a high probability that almost all of the low case count growth in Africa and Southeast Asia as limited testing.

13Richard_Kennaway2moI would like this to be true, but two days on from the above comment, I am not seeing any linearity in the world growth rate (second link above), just three points in a nearly horizontal line a few days ago. The link for BRA+SWE shows the same thing for Brazil even more dramatically. New daily cases is a noisy enough measurement that I wouldn't entertain hope that we are past the exponential phase until seeing at least a week of a flat or declining rate. The site I usually look for stats on is https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6 [https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6] The graph at the bottom right still looks like exponential runaway, even when you switch to daily instead of cumulative cases. And just like the above links, a few days ago there was a period of a few days of seeming flatness in new cases, but it didn't mean anything. Edit: corrected corrupted URL to the arcgis.com site.
18streawkceur2moI'd like to point out that the growth in India is still exponential (linear on the log-scale) https://www.worldometers.info/coronavirus/country/india/ [https://www.worldometers.info/coronavirus/country/india/]. This could be or become true of other developing countries. India and other developing countries probably have a harder time controlling the outbreak (and governments and the young, food-insecure populations may judge the economic cost of social distancing to be higher than the risk of the virus). There was a time when the number of worldwide cases appeared to stagnate because of the Chinese lockdown, but this number just hid the exponential growth of the European+US outbreaks. What I said doesn't contradict any explicit statement in your comment, I just want to argue against the hypothetical deduction from "the growth rate of the world as a whole has also turned linear" to "and this means that the world is over the hill".

April Coronavirus Open Thread

by Elizabeth 1 min read31st Mar 2020140 comments

35


Last month’s Coronavirus Open Thread did a fantastic job at being a place for coronavirus-related information and questions that didn’t merit a top level post, but at almost 400 comments, many of which were great at the time but are now obsolete, it’s getting a little creaky. So for the next month (probably. Who knows what’s going to happen in that month) this is the new spot for comments and questions about coronavirus that don’t fit anywhere else and aren’t worth a top level post.

Wondering what happened in last month’s thread? Here are the timeless and not-yet-eclipsed-by-events highlights:

  • Spiracular on why SARS-Cov-2 is unlikely to be lab-created.
  • Two documents collating estimates of basic epidemiological parameters, in response to this thread
  • Discussion on whether the tuberculosis vaccine provides protection against COVID-19.
  • Suggestive evidence that COVID-19 removes sense of taste and smell.
  • Could copper tape be net harmful?

Want to know what’s coming up in the future? Check out the Coronavirus Research Agenda and its related questions.

Wondering why the April thread is going up on 3/31? Because everything’s a little more confusing on 4/1 and I didn’t want the extra hassle.