Background Influenza is an important public health issue of global concern. Meteorological factors are one of the important factors affecting the incidence of influenza. Exploring the correlation between temperature and influenza can provide a scientific basis for the prevention and control of influenza in specific regions.
Objective To explore the association and attributable risk between temperature and influenza incidence in residents aged 0-14 years in Longhua District of Shenzhen.
Methods Meteorological observation data were collected from the Meteorological Bureau of Longhua District, Shenzhen City from January 2016 to December 2019. A total of 19657 influenza cases among children of 0-14 years old were identified from the China Information System for Disease Control and Prevention during the same period. Spearman rank correlation was used to analyze the correlation between daily incidence of influenza and meteorological factors. Distributed lag non-linear model was used to quantify the association and lag effect of temperature on influenza incidence in different gender and age groups, and to estimate the attributable risk of temperature on influenza incidence.
Results From January 2016 to December 2019, the average daily incidence of influenza in this area was 13.45 cases, and the male to female ratio was 1.36∶1. The proportion of cases in <5 years old and 5-14 years old groups was 50.05% and 49.95%, respectively. The results of Spearman correlation analysis showed that among all meteorological factors, the daily mean temperature had the most significant impact on the daily incidence of influenza, showing a negative correlation r=−0.1541. There was a non-linear exposure-effect relationship between daily mean temperature and influenza incidence in different lag days. There were two peaks in the risk of influenza incidence caused by daily mean temperature at a cumulative lag of 14 d, and the maximum risk was at 11 ℃ (RR=8.15, 95%CI: 5.73, 11.60). In addition, the attributable risks of daily mean temperature on females and residents aged 5-14 years were greater than those on males and other age groups respectively. Both low and high temperatures had effects on influenza, but the proportion of low temperature effect (44.58%) was much greater than that of high temperature effect (4.92%). Low temperature had risk effects on residents of both genders and all age groups, with the greatest effect on residents aged 5-14 years old, and the cumulative risk was the highest at lag 14 d (RR=12.80, 95%CI: 8.29, 18.93). The lag effect of high temperature appeared in residents aged 5-14 years, with the highest cumulative risk at lag 14 d.
Conclusion Temperature significantly influences influenza incidence among children 14 years and under in Longhua District of Shenzhen. In particular, it has a greater impact on girls and people aged 5-14 years old, and low temperature poses a higher risk than high temperature.
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