Review 3: "From Exposure to Detection: Unraveling the Digital Signature of Infectious Diseases and Patient Behavior Using Smartwatches and Patient Self-Reporting"

RR:C19 Evidence Scale rating by reviewer:

• Reliable. The main study claims are generally justified by its methods and data. The results and conclusions are likely to be similar to the hypothetical ideal study. There are some minor caveats or limitations, but they would/do not change the major claims of the study. The study provides sufficient strength of evidence on its own that its main claims should be considered actionable, with some room for future revision.

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Review: The authors use symptom surveys and wearables in a large cohort and followed them through viral/bacterial upper respiratory infections. This study has excellent data collection of symptom data, wearable data and positive test results. The COVID and influenza diagnoses were likely correct due to need for positive diagnostic tests. 

The GAS infections were very high, and likely reflected the inclusion non-GAS pharyngitis due to inclusion of those without positive tests. While these are likely incorrectly diagnosed, the results are still valid for as long as this sub-cohort is considered as 'non-COVID/Influenza pharyngitis' as opposed to GAS pharyngitis.

The limitations regarding the use of non-medical devices are valid. This includes the use of Garmin's stress instead of heart rate variability.