Trends and age-period-cohort effects on the incidence of hand, foot, and mouth disease among children younger than 10 years old from 2009 to 2023 in Quzhou, China

Hand, Foot, and Mouth Disease (HFMD) is a prevalent childhood infectious disease caused by enteroviruses, posing significant public health concerns in China. This study aimed to provide information and evidence to guide public health response and intervention by exploring the trends of HFMD incidence among children under 10 years old in Quzhou from 2009 to 2023, and analyzing the influence of age, period, and cohort. Data on HFMD cases in Quzhou from 2009 to 2023 were collected and then analyzed using Joinpoint regression and age-period-cohort (APC) model to explore incidence trends and potential causes. A total of 75,284 HFMD cases were reported in Quzhou from 2009 to 2023, with children under 10 years old accounting for 99.01% of the cases. The main age group for onset was centered between 1 and 3 years. Before 2017, EV71 was the main pathogen in 3,360 laboratory-confirmed HFMD cases, followed by Cox A16. Since 2018, Cox A16 and Cox A6 have dominated. Serious cases have declined significantly since 2016. Joinpoint regression analysis showed two inflection points (2013 and 2021) with an up-down-up trend. The APC model indicated concentrated risk in children aged 1–3 years, with a periodic fluctuating trend of period effect and an overall increasing trend of cohort effect. The use of EV71 vaccine has temporarily reduced HFMD incidence, but the changing pathogen spectrum has led to a resurgence, highlighting the need to expedite the development and use of vaccines against Cox A strains to mitigate the impact of this disease.