  Through lockdowns and other severe changes to daily life, almost everyone is
affected by the COVID-19 pandemic. Scientists and medical doctors are - among
others - mainly interested in researching, monitoring, and improving physical
and mental health of the general population. Mobile health apps (mHealth), and
apps conducting ecological momentary assessments (EMA) respectively, can help
in this context. However, developing such mobile applications poses many
challenges like costly software development efforts, strict privacy rules,
compliance with ethical guidelines, local laws, and regulations. In this paper,
we present TrackYourHealth (TYH), a highly configurable, generic, and modular
mobile data collection and EMA platform, which enabled us to develop and
release two mobile multi-platform applications related to COVID-19 in just a
few weeks. We present TYH and highlight specific challenges researchers and
developers of similar apps may also face, especially when developing apps
related to the medical field.
