The US hit a major milestone in terms of testing yesterday, as per the Covid Tracking Project over 1 million covid tests have been conducted in the country. This is by far the most of any country that reports these numbers, and considering how late the testing started, it is truly an impressive feat. However, does this mean that we have a good idea of the spread of the virus in the US? There are a few statistics I track that might give us a better indication than just a pure top line number.

Country	# of tests	Tests per 1M in pop	% positive
Norway	90,242	16645	5.14%
Italy	477,359	7896	22.16%
S. Korea	395,194	7713	2.18%
Canada	244,421	6471	3.52%
Austria	49,455	5490	19.79%
Denmark	27,109	4682	10.55%
USA	1,048,971	3171	17.97%
UK	152,979	2251	16.44%

The first obvious thing to do is to scale the number of tests by the size of the population. If I’m in Luxembourg 1 million tests would mean I’ve tested my entire population, twice, but if I am in China that’s not a significant percentage of the population. The US has so far tested approx. 3,200 people per 1M in population, which is the same as saying it’s tested 0.3% of its population. Given that they only started testing a couple of weeks ago, which is far later than all the other countries in the list above, that’s a pretty impressive pace, but in the end it still falls short of where it should be. There is a lot more work to do to get a good sense of where the pandemic is.

Canada is testing at about the same pace as the US per 1M in population right now (roughly increasing by 500 ppl per 1M per day), but we’ve had a solid few weeks in terms of a head start, so we are in a much better shape overall at 6,500 people tested per 1M in population.

The other key statistic to track is the % of positives identified across all cases tested. In general the countries that are testing sufficiently and are able to contain the outbreaks have lower positive rates. This makes sense because they are testing more people who have symptoms but are not covid positive, which in turn means they are not just testing the sickest of the sick but have the capacity to test beyond that. Additionally if the sample can be assumed to be somewhat random, the positive % should be relatively lower for countries where the virus is not as wide spread.

We can see that Italy has a very high positive % despite having tested a large portion of its population. This is not good because it implies they either don’t have the testing capacity to reach the symptomatic people that would test negative, or the country is in fact that infected. The situation there is improving daily, and the rate is starting to come down slightly, so I expect we’ll know the answer soon.

On the other hand the US positive % rate is almost as high as Italys, and it is still increasing daily, which are both very troubling signs. However, as bad as the overall US rate is, the NY state rate is close to 40%!! That means that for every 2 people that get tested in NY state, 1 of them tests positive for covid. That’s truly frightening, and I believe the other major cities in the US are not yet testing enough, so unfortunately I think the worst is still to come.

The situation in Canada is not all roses, as the positive test rate is still climbing, but at 3.52% overall and 6% in worst hit Quebec, I think it’s relatively speaking under control. We will know more when the backlog of test cases is cleared, which is on schedule for the end of this week or latest early next week. I’m cautiously optimistic, but a jump in the positive rate would be an early worrying sign.

Photo by CDC on Unsplash

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The coronavirus pandemic has gripped the world both physically and psychologically. Everyday we see heartbreaking personal stories, terrifying death numbers, and have to give up our basic freedoms in the interest of our communities.

Being a stats geek myself I’ve been following the numbers very closely, somewhat to try to forecast the economic rebound, perhaps a bit our of morbid curiosity, but mostly because I’ve been deprived of the joys of following the stats for my precious World Champion Raptors and their ugly step sibling soon-to-turn-beautiful-swan (we hope), the Maple Leafs. What a red blooded sports following male to do?

Enough about me and my sports stats withdrawals though. Are any of these social distancing measures making any difference at all? The good news is that they appear to be helping.

Week over week changes of active cases per country
March 20->27
Filtered on countries with 500+ cases

Country	Change in active	Previous weeks pace	Acceleration of trend in active
Turkey	741.75%	13120.00%	-94.35%
Pakistan	176.08%	2325.00%	-92.43%
Luxembourg	227.70%	1719.23%	-86.76%
Ecuador	280.53%	2089.47%	-86.57%
Mexico	260.38%	1887.50%	-86.21%
Peru	135.66%	821.43%	-83.49%
Qatar	12.83%	75.57%	-83.03%
Egypt	65.96%	360.78%	-81.72%
Malaysia	99.57%	469.70%	-78.80%
Ireland	210.22%	878.26%	-76.06%
Switzerland	101.42%	393.24%	-74.21%
Colombia	263.19%	1007.69%	-73.88%
Germany	123.79%	441.29%	-71.95%
Czechia	172.50%	590.83%	-70.80%
Chile	264.95%	895.35%	-70.41%
Estonia	99.65%	314.71%	-68.34%
Portugal	311.20%	809.01%	-61.53%
Iceland	95.79%	245.30%	-60.95%
Austria	181.47%	429.98%	-57.79%
Indonesia	185.31%	433.33%	-57.24%
Panama	288.89%	661.54%	-56.33%
Thailand	270.61%	615.38%	-56.03%
Brazil	246.81%	533.77%	-53.76%
Poland	235.63%	507.46%	-53.57%
Saudi Arabia	217.26%	450.82%	-51.81%
Italy	75.42%	153.16%	-50.76%
Dominican Republic	697.14%	1300.00%	-46.37%
Russia	311.25%	548.65%	-43.27%
Slovenia	80.29%	141.13%	-43.11%
Argentina	231.58%	406.67%	-43.05%
Canada	309.80%	535.33%	-42.13%
Spain	171.17%	285.04%	-39.95%
Greece	90.13%	149.20%	-39.59%
South Africa	463.37%	741.67%	-37.52%
Australia	265.14%	414.71%	-36.06%
Netherlands	179.07%	264.39%	-32.27%
UK	264.85%	386.48%	-31.47%
Israel	327.29%	464.75%	-29.58%
France	138.95%	196.22%	-29.19%
Finland	132.73%	185.71%	-28.53%
Belgium	204.41%	263.24%	-22.35%
Singapore	115.35%	146.60%	-21.31%
Hong Kong	162.34%	201.96%	-19.62%
Sweden	83.45%	97.91%	-14.77%
China	-47.33%	-51.29%	-7.72%
Serbia	262.12%	277.14%	-5.42%
Norway	91.95%	96.48%	-4.69%
Philippines	251.96%	257.89%	-2.30%
Denmark	60.08%	55.63%	8.01%
Croatia	340.32%	313.33%	8.61%
Iran	64.15%	56.62%	13.30%
Romania	315.52%	274.32%	15.02%
India	259.28%	211.27%	22.72%
Japan	42.40%	34.22%	23.92%

The virus is still spreading, and will likely continue for a while, but the rate of the spread is decreasing sharply across virtually all countries, with only 6 out of the 58 showing an accelerating trend. In addition, 3 of the 6 showing an acceleration, are already keeping the spread relatively contained, but they are worth watching should this be a start of a reversal in direction.

If we summarize the numbers they look as follows:

Region	Change in active	Last weeks pace	Acceleration of pace of active
World	151.91%	160.04%	-5.08%
World less China	159.77%	213.70%	-25.24%
World less China/US	125.49%	189.92%	-33.92%

I am excluding China because they are on the down slope of the curve and therefore can skew the numbers to make it appear as though there is no improvement in the pace week-to-week. The effect is clearly seen in the table above with World with China included not showing much of a deceleration.

I’m also excluding the US from my analysis for now because they are in a very different stage of this pandemic (testing wise) than the majority of the world, and are a large enough block to muddy the waters. The good news is that the US is testing at a truly impressive pace over the past week, quickly approaching 1 million tests completed, so hopefully we can all have a better picture of the situation there soon.

In summary, we can see that the restrictions most countries have put into place are having a very positive effect on the spread of the virus. I wouldn’t call more than doubling of the active cases in a week a victory, but it certainly beats tripling, and if the deceleration of the trend continues at -33% a week, we should be able to avoid some of the worst case scenarios being talked about in the media.

Clearly the best thing you can do to help is out is to keep re-watching those Netflix shows, play some video games, and stay at home. If you ask me that’s not a bad price to pay to make this go away quicker and save the lives of those vulnerable.

All numbers courtesy of the excellent https://www.worldometers.info/coronavirus/#countries site.

Photo by CDC on Unsplash

I picked one stat for today’s blog post, but there are plenty of others that I am tracking that confirm the trend, and I hope to find some time to post those in the near future.

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