Dear Editor,
We read the article by Louis Tunnicliffe and Charlotte Warren‐Gash 1 with great interest. The author reported that neither population density nor rural/urban status was associated with ILI (influenza‐like illness) symptom rate in England and Wales by using data from an online community‐based cohort called Flusurvey. Although the authors did consider many variables that may affect the result of the study, we believe that additional factors should also be considered to better elaborate on the topic.
According to a previous study, overweight {OR (Odds ratio) = 1.18.95%CI (confidence interval) [1.08; 1.29]} or obese (OR = 1.28.95%CI [1.14; 1.44]) was an important factor that increased the risk for ILI. 2 A recent study 3 also showed that during the 2010–2019 influenza seasons in England, obesity was one of the most common risks that increased the incidence of influenza‐ and pneumonia‐diagnosed medical events (general practitioner [GP] diagnoses, hospitalizations, and deaths). Besides, obese adults typically experienced poor initial and adaptive immune responses to vaccination, leading to impairment of long‐term protection. 4 As a result, we highly recommend the authors to examine the weight of all participants to mitigate potential confounding bias.
In addition, the study did not investigate all age groups for alcohol consumption. Alcohol use disorder (AUD) is one of the risk factors for premature death and disability around the world. 5 And a study 6 reported that middle‐aged adults with AUD had increased risks (p < 0.05) for influenza and pneumonia than younger and older adults with AUD. Given that the median age of participants in this study was 45 (middle age), we recommend the authors investigate the drinking habits to eliminate confounding factor.
In short, we highly appreciate the work by the authors for demonstrating that no evidence for an association between either population density or rural/urban status and ILI symptom rate. We think this study is extremely crucial because influenza and influenza‐like illness are prevalent in rural or urban areas of countries around the world, and this research can provide information for local health units to formulate relevant public health policies. We believe that by taking the aforementioned points into account, the study could provide more helpful information.
CONFLICTS OF INTEREST
The authors declare no conflict of interest.
AUTHOR CONTRIBUTIONS
Chi‐Chih Chan: Writing‐original draft. Yung‐Po Liaw: Supervision.
PEER REVIEW
The peer review history for this article is available at https://publons.com/publon/10.1111/irv.13077.
DATA AVAILABILITY STATEMENT
Data sharing is not applicable to this article as no new data were created or analyzed in this study.
REFERENCES
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Associated Data
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Data Availability Statement
Data sharing is not applicable to this article as no new data were created or analyzed in this study.