Question: Unlike Trump, I wouldn’t advocate for less testing, but the rise in cases does make me wonder what the US testing rate is compared to Europe’s average and China’s average and Brazil’s average.

Answer: When it comes to the sheer volume of tests, the United States has indeed conducted the most tests (nearly 30 million total) of any country in the world (Table 1). Because the US is the third most populous country in the world (behind China and India), one of the richest countries in the world (richest by total GDP, one of the richest by GDP/capita), and one of the most hard-hit countries in the world (most COVID cases; most COVID deaths), we’d expect the US to have conducted a high number of tests. This isn’t a “win” to brag about in my opinion. Let’s look at a few other comparisons: a) testing per capita and b) test positivity rate.

By population, the US testing rate is now higher than most countries, though it is not the highest and it has taken several months for the US to achieve this level (Figure 1). When it comes to test positivity rates, the 7-day rolling average of daily percentage of tests that are positive in the US is 6.1%, 6.8% if NYS is removed (data from covidtracking.com). This positivity level is growing and is higher as compared with Europe and Australia, but lower as compared with South America and parts of Asia (Figure 2). This means that there’s still room to further ramp testing up in the US — higher positivity rates indicate that a proportion of the infected population is likely still untested. On this front, WHO issued guidance stating that positivity rates should be <5% for at least 14 days (assuming surveillance is comprehensive) before governments begin relaxing social distancing measures.

Finally, when it comes to making comparisons with China and Brazil, we are limited by a lack of transparency. As you’ll see in the below tables and charts, China’s data does not appear. That said, China does claim to have conducted the most tests of any country in the world — 90 million per Xinhua, as reported in The Hill on Monday — but experts question the country’s case and death counts. Brazil has also had its share of data transparency issues. Earlier this month, the Supreme Court of Brazil issued an order for the ministry of health to release COVID data. Still, from what we do know, Brazil lags far behind in testing and has the highest test positivity rate of all countries in the world (~37%).

If you want to explore further, here’s another shout-out to Dr. YJ Choi, who keeps updated trend data on the latest comparisons of COVID across OECD countries.

Table 1. Cumulative Tests (from Our World in Data)

Figure 1. Country-level Trends in Daily Testing Rate per 1,000 People (from Our World in Data)

Figure 2. Percentage of Daily COVID Tests that are Positive (from Our World in Data)