Review 2: "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.

***************************************

Review: The ability of smartwatches to inform clinical decision-making is an active area of research where large clinical trials are not often featured. The current work differentiates itself by involving over 4,700 subjects over a two-year period in the collection of data to correlate digital incubation, the incubation period, and the diagnostic decision period to objective smartwatch data and subjective seif-reported data on symptoms. The study results expand our insight on the use of smartwatch data as a precursor to infectious disease symptom onset and contribute to the understanding of how we can potentially manage respiratory disease transmission. Evidence presented has the potential to be used by others in this research domain who have published results based on limited size datasets. 

The literature search follows contemporary procedures, and the manuscript discusses limitations with other work and is clear on how the current work is differentiated. With an emphasis on finding research that affects infection disease transmission dynamics and the need for more robust studies for public health strategy development, the present work advances the field given the limited scope of other studies (identified in the literature search). In the present work, the Boolean scripts used in searching several data repositories provides a solid foundation for the gap in knowledge the study seeks to address. 

Attention to research ethics is clearly presented in this paper and conventional methods are adequately described.

The manuscript has very specific recommendations that are supported by data. There is very little medical jargon in the paper, and this enhances the ability of a broad audience to understand the findings from the research. This is particularly important from a public health perspective in which the actionable items are not buried in a complicated narrative. The message is to educate on the value of early warning signs and suggests alertness to precursor data – even if 2 days ahead of when symptom onset is evident – acting on this early warning information is to be encouraged. Readers experienced in the study of smartwatches will find the authors’ discussion of strengths, weaknesses, and study limitations are within contemporary expectations and this builds the subsequent reliability of the outcomes presented.

The manuscript presents what is a significant undertaking in a clear fashion that will benefit a broad audience.