Trends of routine childhood vaccination status in Afghanistan over the last two decades (1999-2023)

Global vaccine coverage improved substantially. In Afghanistan, routine immunization has been expanding since 1978 but remains inadequate, contributing to consistently high under-five mortality rates. This time-trend analysis focused on national routine childhood immunization coverage and the number of Expanded Programme on Immunization (EPI) centers in Afghanistan from 1999 to 2023.

Data were drawn from World Health Organization/United Nations Children's Fund (WHO/UNICEF) estimates and the "Gavi, the Vaccine Alliance" administrative reports (1999-2018). Seven vaccines were assessed: third dose of polio vaccine (Pol3), first and second doses of measles-containing vaccine (MCV1, MCV2), first and third doses of diphtheria-tetanus-pertussis vaccine (DTP1, DTP3), Bacillus Calmette-Guérin (BCG), and third dose of hepatitis B vaccine (HepB3). Linear spline regression, with knots in 2006 and 2018, was validated.

Between 1999 and 2023, coverage of all seven vaccines increased. WHO/UNICEF data showed Pol3 rising from 27% to 68%, MCV1 from 31% to 55%, DTP1 from 15.2% to 67%, DTP3 from 27% to 60%, and BCG from 38% to 68%, with MCV2 growing from 2% to 42% and HepB3 peaking at 67%. Spline regression revealed rapid growth from 1999 to 2006, slower increases from 2007 to 2018, and declines from 2019 to 2023. Gavi data mirrored these patterns, with DTP3 rising by 7.96% annually from 1999 to 2006 and DTP1 falling by 0.30% from 2007 to 2018. EPI centers expanded by 159.78 per year (2001-2006) and 74.12 (2007-2018).

Afghanistan's immunization coverage increased substantially until 2006, grew more slowly from 2007 to 2018, and declined after 2019. These patterns highlight the vulnerability of routine immunization programs to contextual challenges and suggest that sustaining coverage will require continued strengthening of routine services, monitoring subnational disparities, and implementing conflict-sensitive strategies.