Why comparing COVID statistics is difficult

The Austrian capital is carrying out more PCR tests than the whole of Germany put together. Just a few days ago, Mario Dujakovic, a spokesman for Vienna City Council Health Councillor Peter Hacker, tweeted that Vienna had processed about 2.3 million PCR tests in the second calendar week of this year.

These statistics are currently going viral in Germany and have left a bitter taste in the mouths of some here, given current COVID-19 restrictions. Germany's federal health agency, the Robert Koch Institute (RKI), for instance, conducted about 2 million PCR tests nationwide during the same period — lagging slightly behind Vienna.

The news also comes as test capacities are running low in Germany and the government has decided that fewer people should be allowed to get tested using the more reliable PCR procedure. But how, exactly, is Austria testing so many people? And how are other countries dealing with testing problems?

Austria is doing it at home

Ease of access to PCR tests could be one explanation for Vienna's success. Austrians can also readily purchase saliva rapid tests in drug stores to be used at home. The kits can then be dropped at supermarkets, schools and even gas stations for processing, making the whole endeavor far less staff-intensive on all fronts.

Lab costs are likely considerably lower in Austria, too. That is due to the way that specimens are processed. In Vienna, tests are pooled by Lifebrain, a leading European laboratory operator. That means the contents of 10 kits are tested as a single batch robotically. If the batch is positive, the tests are then analyzed individually. That saves time and money as Lifebrain only charges a few euros to process a single PCR test.

Germany rations testing

In Germany, on the other hand, schools and daycare centers are the only places where PCR tests are pooled — i.e., initially analyzed as a single batch. Yet, despite that labor-saving approach, laboratories are still frequently stretched beyond capacity, meaning deadlines cannot be met. There are also cases of samples going lost.

Now, with PCR test capacities so severely limited, access to them is being restricted further still. On Monday, the German government declared vulnerable people, as well as health workers and caregivers, should be given priority. Everyone else will have to make do with rapid lateral flow tests — even though they often only return a positive result when a person is already highly infectious.

In German national news on Monday evening, Bavarian State Premier Markus Söder (CSU) said that this new approach will mean that the government will have "no idea how high the incidence rate really is" from here on out. To date, Germany has only recorded infections verified via PCR test.

Observers complain that anyone who wants to know whether or not they have COVID-19 will now have to pay for their own PCR tests. This will put people on low incomes — who have been shown to be at greater risk of contracting the virus — at a disadvantage. Germany's states on Monday called on the federal government "to increase PCR test capacities as quickly as possible."

But experts say expanding capacity could be difficult. Germany lacks both the relevant equipment — and would have to compete with other countries on the global market to purchase it — and the specially trained staff essential to PCR test analysis, according to virologist Ulrike Protzer in an interview with the German daily newspaper Süddeutsche Zeitung. 

Denmark — a test leader

In tiny Denmark, a country of only 5.8 million, the number of COVID-19 tests being carried out is also high in comparison to Germany. You can get a lateral flow test in one of over 400 test centers without an appointment. If you want a PCR test, you can register via a national website. Even when demand is high, laboratories are expected to return at least 80% of PCR test results by the following day. Lateral flow tests, as well as PCR tests, cost nothing in Denmark according to officials. By contrast: In Germany, PCR tests range in price — depending on the provider — from about €50-€70 ($56-$79) if you do not belong to a high priority group.

Denmark has been a testing trailblazer since the start of the pandemic, carrying out some 117 million tests — half of them PCR and the other half lateral flow tests — according to Danish health authorities.

Israel makes do with rapid tests  

Israel, too, has changed its test strategy and shifted towards rapid antigen tests. Like Germany now, Israel had previously sharply limited access to PCR tests because its health system was overstretched. Now, PCR tests are only available to the elderly and people with preexisting health conditions.

As a result, there has been a run on lateral flow tests, which quickly sold out in drug stores despite costing about seven euros each —  slightly more expensive than in Germany. However, Israel now plans to distribute up to 30 million free COVID-19 rapid tests, in particular to those on low incomes. It is being left up to individuals to inform the authorities of a positive result. 

Complex game of numbers

The varying test strategies adopted by different countries demonstrate just how difficult it is to compare COVID-19 statistics internationally. Test procedures not only differ in accuracy, but ease of access to PCR tests varies from country to country, too. Moreover, those countries that rely on citizens to voluntarily inform them of positive results could be skewing the accuracy of the data as well.

This article was originally written in German