JMIR Publications

ABSTRACT

Exposure notification applications (ENA) were used in several countries during the coronavirus disease 2019 pandemic. Here, we share our experience of implementing and running the Finnish ENA (Koronavilkku), one of the national ENAs with the highest proportion of users during the pandemic. The trade-off between data privacy and ability to measure effectiveness was discussed and decided before app development started. In our view, focusing on privacy and security in implementation and communication strengthened public trust and increased app uptake. On the other hand, prioritizing privacy limited the utilization of the app as a tool for health care professionals. Development and launch were accomplished in just over two months. In our view, open communication and low hierarchy in the multi-organizational team enabled us to adhere to the tight timeline. The predefined target of 40 percent uptake in the population was achieved within three months of the launch. We consider easy to understand information produced together with communication experts crucial during the changing epidemic situation. This educated people about the app as one component in mitigating the epidemic. A few months after the launch, Finland joined European interoperability, which allowed the ENA to share information with ENAs of other countries. We added automatic token issuing to the ENA as of mid-2021. If added earlier and more comprehensively, automatization could have more effectively saved resources and prevented overburdening the contact tracing teams, while also notifying potentially exposed persons quicker and more reliably. In the spring of 2021, the number of active apps started to gradually decline. Quarantine and testing practices for asymptomatic vaccinated persons following exposure to the virus were eased and home tests became more common, eventually replacing laboratory testing for much of the population. Taken together, this led to decreased token issuance, which weakened the potential usefulness of the app. The ENA was discontinued in mid-2022. Regularly conducted surveys would have helped gain timely knowledge on the use and effectiveness of the app for better responding to the changing needs during the epidemic.