Vaccination Coverage and Adherence to Scheduling in Children Aged 0 to 18 Months: Effects of COVID-19 and Age

Vaccination in Peru began 50 years ago as part of the Expanded Program on Immunization (EPI), which has proven effective in saving the lives of millions of children. This research aimed to determine the coverage and adherence to the vaccination schedule in children up to 18 months of age during the period 2018–2022, including the COVID-19 pandemic lockdown, in order to assess its influence. Materials and methods: This was a secondary source study based on the Demographic and Family Health Survey (ENDES) of Peru, including a sample of 82,702 male and female children whose caregivers presented vaccination cards. Coverage and adherence indicators were calculated, and differences were evaluated between the pre-confinement, absolute confinement, and relative confinement periods using a chi-square test. Results: For almost all vaccines, coverage decreased from 2018 to 2022 (from 82.46% to 80.16% on average, p < 0.001). Coverage also decreased as the scheduled age increased (0–2 months: median 93%, 7–18 months: median 63%; p < 0.001). Average adherence rates also declined over time (2018: 65.82% to 2022: 61.77%). The most affected vaccine was the yellow fever vaccine. Coverage did not reach protective population levels, while adherence has averaged 85.06% since 2018. Conclusions: COVID-19 negatively influenced compliance with the vaccination schedule and adherence.