An App for Apple Watch and Fitbit to help battle COVID-19

Recent news that Apple and Google will collaborate on a contact tracing system is cause for celebration, as is the proposal by some to have near universal testing for the coronavirus, and antibodies.  This post proposes an additional App to help in this fight.

Apple Watch and Fitbit both provide a feature to measure the resting heart rate.  A study published in JAMA Internal medicine in 1986 studied the relationship between fever and heart rate.  They reported that for each increase in body temperature by one degree centigrade, the person’s heart rate increased by 8.5 beats per minute.  This correlation could be used to alert user’s when they probably have a fever.  This correlation is probably not sufficiently consistent for each individual to be able to predict body temperature, but it could be used to alert when a fever threshold is passed.  It is not possible to infer the percentage of false positive and false negatives this App might produce without first building the App, and putting it to use with a very large test group.

In addition to alerting the user of the Apple Watch or Fitbit, this could alert a contact tracing App, about the alert.  Giving the contact tracing App a proactive notification should increase the percentage of infected users who report their infection to their contact tracing App.

Anonymized fever alerts could also be aggregated and used to provide a global heat map that provides some of the earliest information about regions where the infection is growing.  The internet enabled Kinsa thermometer is already doing this, but the number of these thermometers is far less than the Apple Watch and Fitbit, and the thermometer must be actively used to take a temperature.