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.
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”.
I 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 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.
How much of that is a delayed effect of distancing and how much is saturation of test capacity? American capacity hasn’t increased in days, and by both my and the Imperial College of London’s calculations, at least 3 million Italians are probably already infected...
I think there’s a decent amount of correlation with between lockdown dates and entering linear growth. Below are the lockdown dates and starts of the linear phase for some of the worst hit countries.
China 23rd Jan → 5th Feb
S. Korea 20th Feb → 1st March (This wasn’t a mandated government lockdown but people did seem to stay inside in the worst hit areas)
March:
Italy 9th → 21st
Spain 15th → 26th
Germany 16th → 27th
France 17th → not yet linear (last 2 days have been high)
Switzerland 20th → 21st
US 22nd (NY) → not yet linear
UK 23rd → approaching linear? Possibly already there
These are remarkably consistent at 10-14 days, apart from Switzerland (very fast) and France (looked like it had gone linear at about the normal time but has increased again).
This graph shows the same data but is annotated with containment steps taken by each country (it isn’t averaged over 3 days so the exact numbers don’t match up but the same pattern applies).
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.
I’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/. 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”.
I 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
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.
How much of that is a delayed effect of distancing and how much is saturation of test capacity? American capacity hasn’t increased in days, and by both my and the Imperial College of London’s calculations, at least 3 million Italians are probably already infected...
I’ve been forecasting a high probability that almost all of the low case count growth in Africa and Southeast Asia as limited testing.
I think there’s a decent amount of correlation with between lockdown dates and entering linear growth. Below are the lockdown dates and starts of the linear phase for some of the worst hit countries.
China 23rd Jan → 5th Feb
S. Korea 20th Feb → 1st March (This wasn’t a mandated government lockdown but people did seem to stay inside in the worst hit areas)
March:
Italy 9th → 21st
Spain 15th → 26th
Germany 16th → 27th
France 17th → not yet linear (last 2 days have been high)
Switzerland 20th → 21st
US 22nd (NY) → not yet linear
UK 23rd → approaching linear? Possibly already there
These are remarkably consistent at 10-14 days, apart from Switzerland (very fast) and France (looked like it had gone linear at about the normal time but has increased again).
This graph shows the same data but is annotated with containment steps taken by each country (it isn’t averaged over 3 days so the exact numbers don’t match up but the same pattern applies).