ABSTRACT
Background The COVID-19 pandemic has significantly disrupted healthcare systems at all levels globally, notably affecting routine healthcare services such as childhood immunisations. This study delves into the impact of these disruptions on routine childhood vaccination programs in Tanzania. Methodology We conducted a longitudinal study over four years in five Tanzanian regions: Mwanza, Dar es Salaam, Mtwara, Arusha, and Dodoma. The study analysed trends in the usage of six key vaccines: Bacille Calmette-Guérin (BCG), Bivalent Oral Polio Vaccine (bOPV), Diphtheria Tetanus Pertussis, Hepatitis-B and Hib vaccine (DTP-HepB-Hib), measles-rubella (MR), Pneumococcal Conjugate Vaccine (PCV), and Rota vaccines. We evaluated annual and monthly vaccination trends using time series and regression analyses. Predictive modelling was performed using an Autoregressive Integrated Moving Average (ARIMA) model. Results The study recorded a total of 32,602,734 vaccination events across the regions from 2019 to 2022. Despite declining vaccination rates in 2020, there was a notable rebound in 2021, indicating the resilience of Tanzania's immunisation program. The analysis also highlighted regional differences in varying vaccination rates when standardised per 1000 population. Seasonal fluctuations were observed in the monthly vaccination rates, with BCG showing the most stable trend. Predictive modelling of BCG indicated stable and increasing vaccination coverage through 2023. Conclusion The findings underscore the robustness of Tanzania's childhood immunisation infrastructure in overcoming the challenges posed by the COVID-19 pandemic, marked by a strong recovery in vaccination rates post-2020. We provide valuable insights into the dynamics of vaccinations during a global health crisis and highlight the importance of sustained immunisation efforts in maintaining public health.