Trends In Routine Immunization Adherence for Vaccine-Preventable Diseases Among Infants in Delta State, Nigeria During the Covid-19 Pandemic

Abstract

Background: Routine immunization is vital for preventing vaccine-preventable diseases (VPDs) and reducing infant mortality. In Delta State, Nigeria, progress has been inconsistent, with major setbacks following COVID-19 service disruptions.

Methods: A retrospective longitudinal study analyzed 842,779 infant immunization records from the Delta State Ministry of Health covering January 2018–December 2022. Data on immunization coverage, dropout rates, and vaccine-preventable diseases were examined using descriptive statistics and paired t-tests in IBM SPSS version 26.0, comparing pre-pandemic (2018–2019), pandemic, and post-pandemic (2020–2022) periods (p < 0.05).

Results: Among 842,779 infant records analyzed, 52% were male and 48% female, with 62% residing in rural areas. Full immunization coverage improved from 67% in 2018 to 78% in 2019, but declined to 61% in 2020, recovering slightly to 63% in 2022 (p = 0.04). Uptake of the Hepatitis B birth dose increased from 31% to 49%, reflecting more facilitybased deliveries. Measles second-dose administration rose markedly from 11,814 in 2018 to 95,462 in 2022. However, coverage for Diphtheria, Pertussis, and Tetanus (DPT3) and yellow fever vaccines declined, with Pentavalent 3 dropout rates rising from 8.2% to 9.9%. Infant mortality peaked at 14.4 per 1,000 live births in 2020.

Conclusion: Despite gains in Hepatitis B and measles coverage, overall routine immunization remains fragile. Strengthened monitoring, resilient service delivery, and targeted outreach to underserved populations are essential to restore coverage, close immunity gaps, and reduce preventable infant deaths.