Recently, new forms
of surveillance based upon the social internet have emerged; these
data streams are appealing in large part because of their real-time
nature and the low cost of information extraction, properties
complementary to traditional methods. The basic insight is that
people leave traces of their online activity related to health
observations, and these traces can be captured and used to derive
actionable information. Two main classes of trace exist: sharing
such as social media mentions of face mask use [35] and healthseeking
behavior such as web searches for health-related topics
[36]. (In fact, there is evidence that the volume of internet-based
health-seeking behavior dwarfs traditional avenues