Objective To investigate the association between the number of children hospitalized with influenza and air temperature in Hengshui, Hebei Province, China.

Methods Based on the data of children hospitalized with influenza registered in Hengshui Center for Disease Control and Prevention from 2014 to 2019, the exposure-response relationship between air temperature and the number of children hospitalized with influenza in Hengshui was analyzed by the distributed lag nonlinear model.

Results The outbreak of influenza in children was mainly observed in winter, accounting for 57% of all the year, followed by spring with 22%, with fewer cases in summer and autumn. The influence of air temperature on the number of children hospitalized with influenza varied across different ages. At the air temperature of -5 ℃ and -2 ℃, the cumulative effect of children aged 0-6 years reached the maximum cumulative relative risk at lag day 14, which were 9.998 (95%CI: 3.259, 30.674) and 5.468 (95%CI: 1.777, 16.821), respectively, while there was no significant difference in cumulative effect in children aged 7-14 years old. At the air temperature of 32℃, the maximum cumulative relative risk in infants and young children was observed at lag day 14 and lag day 11, respectively, which were 5.857 (95%CI: 1.442, 23.785) and 14.400 (95% CI: 1.061, 195.422), respectively. The young children were more sensitive to high temperature.

Conclusion Both low and high temperatures can increase the risk of influenza in children, with a significant lag effects.