Clarification on Diagnostic Testing Data in OECD Analysis on Testing for COVID-19

On April 17th OECD released a policy brief by the Employment, Labour & Social Affairs Directorate on “Testing for COVID-19: A way to lift confinement restrictions”. The main message in this brief was and remains to strongly encourage countries to scale up their efforts on testing in the context of the current coronavirus crisis.

One of the charts contained in the brief related to diagnostic testing rates per 1,000 population. After assessing the various options for these data, the determination made was that the most reliable available data was to be found in Our World In Data (OWID). As such data becomes rapidly outdated given the current fast-moving context, and as additional data would become available, it was recognised that this chart would require regular updating and expansion. Consequently, a new revised version was prepared after a week had elapsed from the original issue, on April 24th.

Given that country coverage of diagnostic testing in the OWID data was still incomplete, efforts were made to extend it where possible. In this context, when the Spanish authorities made available new detailed and disaggregated data, compiled by the Health Ministry and the Institute of Statistics, including both PCR and serological tests, and the aggregate of the two, our experts made the decision to include the aggregate figures in the chart which was released yesterday morning.

OWID have subsequently clarified that they seek to include only data on PCR tests. Following release of the official Spanish data yesterday, OWID has included Spain in the list of countries with testing data, including just the PCR and leaving out serological tests. To ensure consistency with the same data source, the policy brief will, henceforth, refer to OWID data and be periodically updated accordingly. This is without prejudice to the fact that it is a welcome development that countries are also engaging in producing serological tests. Whether they are included or not in the comparators, they are important tools to inform the strategy to address the pandemic.

It is important to note that international comparability of all testing figures is limited, as differences exist as to whether figures include tests, or individuals tested; whether they include all lab tests (public and private) or not; and on how regularly data is updated by each country.

We regret the confusion created on a sensitive issue by any debate on methodological issues. Independent of the exact position in which one or another country may find themselves in such charts at any given time, the most fundamental issue to retain is the fact that the countries, including Spain, have increased the number of tests available, affording testing the priority and importance it deserves as this is the most important element in order to improve the ability of countries to control the spread of the virus. OECD reiterates the need to continue and strengthen such efforts as, without testing, the lockdowns will be longer than they need to be.

/Public Release. View in full here.