Abstract

The CoronaMelder app was designed to combat the spread of the coronavirus (SARS-CoV-2) in the Netherlands. The app sends a message to users who spend more than 15 minutes within 1.5 m of a person with Corona, which enables them to quickly get tested and go into quarantine if necessary. This prevents them from infecting others with the virus and thereby helps in bringing the epidemic under control.

In the first months, the app made a positive but small contribution to the fight against the coronavirus. From 1 December 2020 up to and including 31 March 2021, 7514 persons tested positive after a message from the CoronaMelder. This prevented an estimated 15,000 infections. The R-value (the average number of new infections caused by one infected person) was 12.7% lower as a result of the combination of testing, the regular contact tracing programme, and the CoronaMelder. The app itself was responsible for a decrease of 0.3%. During the study period, 16% of the Dutch population used the app.

If the measures aimed at limiting interpersonal contacts are relaxed, the number of contacts with unknown persons will increase once again. Testing and the regular contact tracing programme will then become less effective. The CoronaMelder can pick up some of the slack in this regard. The app would be more effective if users themselves could inform their contacts in the app. Now the Municipal Health Services does this. It is also important for more people to use the app than is now the case.

This is made clear in an evaluation by RIVM of the CoronaMelder’s effect, in combination with testing and the regular contact tracing programme. The effect of the app between 1 December 2020 and 31 March 2021 was estimated using model calculations. The starting date chosen was 1 December, as it became possible from this date onwards to request a test after receiving information from the contact tracing programme or the CoronaMelder even without having any symptoms.