Evaluation of the impact of COVID-19 on hepatitis B in Henan Province and its epidemic trend based on Bayesian structured time series model

Background There may be evidence that COVID-19 affects illness patterns. This study aimed to estimate epidemiological trends in China and to assess the effects of COVID-19 epidemic on the declines in hepatitis B (HB) case notifications. Methods The Bayesian structured time series (BSTS) method was used to investigate the causal effect of COVID-19 on the decline in HB cases based on the monthly incidence of HB from January 2013 to September 2022. To assess how well the BSTS algorithm performs predictions, we split the observations into various training and testing ranges. Results The incidence of HB in Henan was generally declining with periodicity and seasonality. The seasonal index in September and February was the smallest (0.91 and 0.93), and that in March was the largest (1.19). Due to the COVID-19 pandemic, the monthly average number of notifications of HB cases decreased by 38% (95% credible intervals [ CI ]: -44% ~ -31%) from January to March 2020, by 24% (95% CI : -29% ~ -17%) from January to June 2020, by 15% (95% CI : -19% ~ -9.2%) from January to December 2020, by 11% (95% CI : -15% ~ -6.7%) from January 2020 to June 2021, and by 11% (95% CI : -15% ~ -7.3%) from January 2020 to December 2021. From January 2020 to September 2022, it decreased by 12% (95% CI : -16% ~ -8.1%). From 2021 to 2022, the impact of COVID-19 on HB was attenuated. In both training and test sets, the average absolute percentage error (10.03%) generated by the BSTS model was smaller than that generated by the ARIMA model (14.4%). It was also found that the average absolute error, root mean square error, and root mean square percentage error generated by the BSTS model were smaller than ones generated by the ARIMA model. The trend of HB cases in Henan from October 2022 to December 2023 predicted by the BSTS model remained stable, with a total number of 81,650 cases (95% CI : 47,372 ~ 115,391). Conclusions After COVID-19 intervention, the incidence of HB in Henan decreased and exhibited clear seasonal and cyclical trends. The BSTS model outperformed the ARIMA model in predicting the HB incidence trend in Henan. This information may serve as a reference and provide technical assistance for developing strategies and actions to prevent and control HB. Take additional measures to accelerate the progress of eliminating HB.