1/ If we want to avoid situations in this pandemic in which we have to make the decision between more people dying or lockdown, we should increase testing.

It needs to be very easy for people to find out whether they are infectious or not.
2/ The number of tests is not the relevant statistic – a large outbreak needs more tests.

How many tests are needed depends on how many people are infected.

That’s the ratio of cases to tests: the *positive rate of tests* is telling us whether a country does enough tests.
3/ If a country tests enough, the positive rate is low. The country does many tests for each case they find.

You want to be in a situation where it's easy for people to find out whether they are infectious.
Whether you achieved that is visible in a low positive rate.
4/ Look for example at Korea, whenever cases increased they increased their testing.

[Here is our study on how they did that and how they followed up on positive cases and allowed people to isoolate (it's a short read): ourworldindata.org/covid-exemplar…]
5/ That Korea was successful in providing enough tests is visible in their very low positive rate.

Below 1% means that they do 100 tests for each case they find.
The WHO recommends to achieve a rate below 5%, better below 3%.
6/ Europe was in the fortunate situation in the summer months that they had time to increase their testing capacities. And they did.

We test more than in the first wave. More people who are sick know that they are sick and can avoid infecting others. That's very good.
7/ But crucially European countries did not expand testing nearly enough. The countries in shades of red all test way too little, their positive rate is high.

In these countries many people are sick, but don't know it.
9/ The goal is to never get into the situation where you have to choose between more deaths or lockdowns.

Look what the positive rate of countries that got closer to that goal than others. (I included the US to show the contrast.)

[source ourworldindata.org/coronavirus-da…]
10/ In February we made the decision in @OurWorldInData to focus on testing and we built the international COVID-19 testing database.

Our paper is here nature.com/articles/s4159…

We also make all our data available so that you can research for yourself github.com/owid/covid-19-…
11/ It’s been frustrating to see how very slowly testing has expanded.

Many governments did very little to get their populations into a position where they know what is happening – to others and themselves – so that they can respond to the situation appropriately.
12/ Expanding testing massively is so attractive because it is cheap. Really extremely cheap relative to the huge costs of lockdowns or people dying.

@paulmromer estimates that the returns are at least 10x
For very cheap tests perhaps up to 100x !

13/ Testing is of course not the only strategy that we should work towards. There is no single strategy ever for any big problem in the world.
14/ But the reality is that this pandemic isn't over any time soon.

And I believe that if we want to avoid these awful situations where we have to choose between lockdowns and deaths we should give people the chance to know whether they are infectious or not.
15/ Whether countries are achieving this is visible in a low positive rate.

You can see the positive rate in our page on testing, ourworldindata.org/coronavirus-te…, it's the very first map on that page.

We update it all the time, for many months now.
16/ We should make it our goal to avoid getting into these awful situations where it's a choice between lockdown or the deaths of more people.

I believe a crucial step for this goal is to provide enough tests. Let's make it our goal to turn that map blue.

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More from @MaxCRoser

28 Oct
This is to me one of the saddest and most important charts on the pandemic.

Those countries that are doing bad right now (high on the y-axis) are largely the same countries that did worst overall in this pandemic (cumulative case rate until Aug 1 on x-axis). Image
This is a slightly different version of the same chart.

Here the x-axis shows the cumulative case rate up to the present (which means some of the correlation is simply due to current cases counting towards cumulative cases).

And with the color showing the postive rate. Image
This chart would show us when a country reaches herd immunity.

A country that actually achieves herd immunity will have a high cumulative case rate and the current case rate will be low → it will end up in the bottom right corner (where no country is right now).
Read 5 tweets
20 Oct
The rise of confirmed cases in Europe is very rapid.

– This is showing the 7-day rolling average. Over the last week 138,500 cases were confirmed every day.
– The doubling time of confirmed cases for Europe as a whole is two weeks.

[interactive source ourworldindata.org/coronavirus-da…]
But as always, confirmed cases are only a fraction of total cases.

And testing has become worse in the last weeks – the positive rates have increased in many European countries – so that the true doubling rate is likely quite a bit faster.

[source ourworldindata.org/coronavirus-da…]
And across European countries that differences are large.

Belgium & the Czech Republic report more than 700 cases per million every day.

On the other hand Estonia & Norway report fewer than 30 per million. Testing there is better so that the true difference is likely larger.
Read 13 tweets
18 Oct
1/n] The pandemic will end when we reach herd immunity. The question is how we get there.

In a world without science and technological innovation there would be no alternative: The only way to achieve immunity is for a large share of the population to get infected.
2] But that’s not the world we live in. We can achieve herd immunity via a vaccine.
3] So it's a question of how optimistic we are about medical innovation.
Being in favour of a high infection rate now makes sense if you are pessimisic about the world's chance to develop a vaccine or to make progress towards good antivirals.
Read 8 tweets
18 Oct
The cumulative death rate – since the start at the pandemic – in European countries.

The 5 countries where most lives were lost are: Belgium, Spain, the UK, Italy, and Sweden.

The countries that did well – those at the bottom – suffered a death rate that was 10-times(!) lower.
And these are the current positive rates of testing. Those countries that did poorly in containing the pandemic were – and are – also doing poorly in testing.

Belgium, Spain, UK, Italy, and Sweden have high positive rates.

Especially Finland, Norway, and Denmark are doing well.
You can explore all this data for yourself in our Data Explorer ourworldindata.org/coronavirus-da…

There you also find global data and data on confirmed cases, number of tests, and much more
Read 4 tweets
9 Oct
What will the global decline of economic growth mean for extreme poverty?

• Orange is the pre-COVID scenario.
• The rise of poverty shows us what to expect under a contraction in global growth this year of 8 percent and 5 percent, respectively.

This is very, very bad. Image
The global goal of ending extreme poverty globally was out of reach before the pandemic as I and many others have written last year.

It would have required all countries to grow at 7 percent annually.
Now with the global pandemic it is not realistic at all sadly.

(Reaching the 2030 would now require all countries to grow at rates of 8 percent per year between 2021 and 2030 and this we cannot realistically expect.) Image
Read 5 tweets
9 Oct
1/n] I think it's a very good decision to give this year's Peace Nobel to the World Food Programme.

Hunger is one of the world's biggest problems and the WFP – one of the UN insitutions that works outstandingly well – is making the world a better place.

2] The world has made a lot of progress against hunger. This is the decline of famine deaths over time.

The WFP helped to avert possible famines in southern Africa (1991–92 & 2000–01), Afghanistan (2001), and western Africa (2012).

[Our work on famines: ourworldindata.org/famines]
3] But hunger remains a massive problem – 11% of the world population are undernourished.

And after decades of progress the share of people that are undernourished has not fallen in recent years.

[@_HannahRitchie's work on hunger on @OurWorldInData: ourworldindata.org/hunger-and-und…]
Read 5 tweets

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