Risk-factors Associated with Non-Vaccination in Gambian Children: A Population-Based Cohort Study

Abstract

Objective We determined the risk-factors associated with children who remain unvaccinated in rural Gambia. Methods We conducted prospective demographic surveillance and recorded immunizations in real-time in the Basse Health and Demographic Surveillance System. Analysis included residents born between January 1, 2012 and December 31, 2016. Demographic data included age, sex, household members and relationships, migrations, births, deaths, ethnicity, residential location, and birth type. Children were defined as unvaccinated at 10-, 15-, and 24-months of age, if they missed all primary series doses (pentavalent, oral polio and pneumococcal conjugate vaccines), secondary series (1st dose measles and yellow-fever vaccines) or both vaccination series, respectively. Multivariate three-level mixed effects logistic regressions measured the strength of association between risk-factors and being unvaccinated at age 10-, 15-, and 24-months. Findings 38,090 infants were born during the study period, while 30,832 survived as residents and 1,567 were unvaccinated at age 10 months. Being unvaccinated at 10-months of age was associated with children not residing with their father (adjusted odds ratio [aOR] 1.38, 95% CI 1.22–1.58) or mother (aOR 2.94, 95% CI 1.33–6.46) or both parents (aOR 2.26, 1.60–3.19), whose parents were not the head of household (aOR 1.29 (1.09–1.52), experiencing external in-migration (aOR 2.78, 95% CI 1.52–5.08) and not of Mandinka ethnicity (aOR varied between 1.57 to 1.85 for three other ethnicities). Conclusion Unimmunised children in rural Gambia are more likely to not live with their parents and have migrated into the area. These results may inform strategies to increase vaccine coverage.

Determinants of pentavalent and measles vaccination dropouts among children aged 12–23 months in The Gambia

“…Over the last two decades, the programme has been introducing new and underused vaccines into The Gambian routine services. These vaccines include hepatitis B – HepB (introduced in 1990), Haemophilus influenzae type b – Hib (introduced in 1997), pneumococcal conjugate vaccine – PCV (introduced in 2009), measles-mumps-rubella second dose – MMR (2012), rotavirus vaccine – RV (introduced in 2013), inactivated polio vaccine – IPV (introduced in 2015), meningitis A – MenA (introduced in 2019), and human papillomavirus vaccine – HPV (introduced in 2019) [ 2 , 15 ]. The Gambia routine immunization programme recommends that the BCG, the first dose of polio, first dose of HepB should be given at birth [ 13 ].…”

“…Vaccination is considered the most successful and cost-effective public health intervention against infectious diseases [ 1 , 2 ]. Each year, about 3 million deaths among children are averted from vaccine-preventable diseases (VPDs) such as diphtheria, tetanus, pertussis, influenza, and measles [ 3 ].…”

“…These statistics may indicate that a certain proportion of children are dropping out of immunization programs. It is noted that a few researchers have focused on the factors associated with either individual immunization coverage [ 13 ], full immunization [ 13 , 14 ], or non-vaccination in the Gambia [ 2 , 15 ]. However, only one study reported the dropouts between vaccine doses [ 16 ], yet no single associated factor was considered in that study.…”