JMIR Public Health and Surveillance (Sep 2024)

Exploring the Birthday Week Effect on Hand, Foot, and Mouth Disease in Yunnan Province, China, From 2008 to 2022: Surveillance Data Analysis

  • Pei Jiang,
  • Xiangyu Yan,
  • Tongjian Cai,
  • Longxin Huang,
  • Zhenzhong Liu,
  • Linhui Hao,
  • Tian Huang,
  • Haijun Yang,
  • Min Xu,
  • Wenhui Shi,
  • Tiejun Shui

DOI
https://doi.org/10.2196/59237
Journal volume & issue
Vol. 10
pp. e59237 – e59237

Abstract

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Abstract BackgroundHand, foot, and mouth disease (HFMD) is a notable infectious disease predominantly affecting infants and children worldwide. Previous studies on HFMD have primarily focused on natural patterns, such as seasonality, but research on the influence of important social time points is lacking. Several studies have indicated correlations between birthdays and certain disease outcomes. ObjectiveThis study aimed to explore the association between birthdays and HFMD. MethodsSurveillance data on HFMD from 2008 to 2022 in Yunnan Province, China, were collected. We defined the period from 6 days before the birthday to the exact birthday as the “birthday week.” The effect of the birthday week was measured by the proportion of cases occurring during this period, termed the “birthday week proportion.” We conducted subgroup analyses to present the birthday week proportions across sexes, age groups, months of birth, and reporting years. Additionally, we used a modified Poisson regression model to identify conditional subgroups more likely to contract HFMD during the birthday week. ResultsAmong the 973,410 cases in total, 116,976 (12.02%) occurred during the birthday week, which is 6.27 times the average weekly proportion (7/365, 1.92%). While the birthday week proportions were similar between male and female individuals (68,849/564,725, 12.19% vs 48,127/408,685, 11.78%; χ21Pχ23Pχ211PZPPP ConclusionsThis study identified a novel “birthday week effect” of HFMD, particularly notable for infants approaching their first birthday and those born during peak epidemic months. Improvements in surveillance quality may explain the declining trend of the birthday week effect over the years. Higher exposure risk during the birthday period and potential biological mechanisms might also account for this phenomenon. Raising public awareness of the heightened risk during the birthday week could benefit HFMD prevention and control.