Review 1: "United States Influenza 2022-2023 Season Characteristics as Inferred from Wastewater Solids, Influenza Hospitalization and Syndromic Data"

RR:C19 Evidence Scale rating by reviewer:

• Strong. The main study claims are very well-justified by the data and analytic methods used. There is little room for doubt that the study produced has very similar results and conclusions as compared with the hypothetical ideal study. The study’s main claims should be considered conclusive and actionable without reservation.

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Review:

The study, "United States influenza 2022-2023 season characteristics as inferred from wastewater solids, influenza hospitalization and syndromic data" describes using IAV virus detected in wastewater to identify correlations and eventually infer clinical indicators (e.g., hospitalization rates). It explores the potential to determine baseline viral wastewater concentrations that coincide with IAV onset, offset, and peak, therefore permitting disease transmission to be monitored and predicted through wastewater surveillance.

The paper presented an analysis of viral concentrations of IAV in wastewater and the relationship with clinical data on a national scale. These WBE approaches are critical not only for different pathogens (besides that of IAV or SARS-CoV-2), but also to assess its utility on different spatial levels. In my opinion, I think the introduction would benefit from a brief description of the current state of WBE analyses and why establishing baseline viral concentrations in wastewater is so critical. This is still a perplexing problem for SARS-CoV-2, given that so many communities monitor for the virus and that cases, and now even hospitalizations, are no longer reliable clinical data. Identifying a baseline viral concentration in wastewater for IAV (or even SARS-CoV-2), can greatly improve public health interpretation of disease spread and therefore, decision-making. I would also recommend including a statement regarding the stability of IAV in the wastewater system, enabling it to be an appropriate pathogen for wastewater monitoring programs. 
A very important point is made in the discussion regarding a higher than normal influenza season during the summer of 2022, which may have affected the analysis. A brief description or statement regarding how the COVID-19 pandemic may have affected the spread, cases, and hospitalizations associated with IAV would be informative. I would also encourage the authors to elaborate upon the public health action that can stem from this work. The methods, statistical analyses, and discussion of the data are all very strong for this paper. For the everyday public health practitioner, what does this mean? How could they implement it at the city or county level?  
Overall, this study is very well done and has tremendous potential. My only critique would be to elaborate on the public health potential of this work, outside of the scope of the statistical analyses conducted.