  The rapid evolution of the COVID-19 pandemic has underscored the need to
quickly disseminate the latest clinical knowledge during a public-health
emergency. One surprisingly effective platform for healthcare professionals
(HCPs) to share knowledge and experiences from the front lines has been social
media (for example, the "#medtwitter" community on Twitter). However,
identifying clinically-relevant content in social media without manual labeling
is a challenge because of the sheer volume of irrelevant data. We present an
unsupervised, iterative approach to mine clinically relevant information from
social media data, which begins by heuristically filtering for HCP-authored
texts and incorporates topic modeling and concept extraction with MetaMap. This
approach identifies granular topics and tweets with high clinical relevance
from a set of about 52 million COVID-19-related tweets from January to mid-June
2020. We also show that because the technique does not require manual labeling,
it can be used to identify emerging topics on a week-to-week basis. Our method
can aid in future public-health emergencies by facilitating knowledge transfer
among healthcare workers in a rapidly-changing information environment, and by
providing an efficient and unsupervised way of highlighting potential areas for
clinical research.
