Why Some Kids Miss Critical Vaccines Even When Shots Are Available: A Mali Study Reveals the Real Barriers

A comprehensive study in Mali's N'Gabacoro Droit Health Area discovered that missed vaccination opportunities persist not because of vaccine shortages, but because of knowledge gaps among both health workers and parents. Researchers surveyed 375 mothers and 10 health workers between January and March 2024, finding that structural problems and misinformation—rather than supply issues—are preventing children from completing their immunization schedules.

What Are "Missed Opportunities" in Vaccination?

Missed opportunities for vaccination (MOV) occur when a child visits a health facility but doesn't receive a vaccine they're due for, even though the vaccine is available. In N'Gabacoro Droit, this was a persistent problem. The study found that 6.15% of surveyed children had not received their third pentavalent dose (which protects against five diseases), and 4.55% had missed their first dose entirely. Even more striking, over 44% of children had not received measles vaccines, and 44.82% had not received yellow fever vaccines.

Why Are Health Workers Missing These Opportunities?

The research uncovered a troubling pattern: health worker knowledge gaps were a major driver of MOV. When researchers assessed the 10 health workers in the health area, they found that four out of ten identified incorrect contraindications for vaccines—meaning they believed certain conditions made vaccines unsafe when they actually didn't. Only nine of the ten health workers fully understood the complete vaccination schedule. These misconceptions directly translated into missed chances to vaccinate children who came through the clinic doors.

Beyond knowledge deficits, the study identified several structural and behavioral barriers that compound the problem:

• Health System Inefficiencies: Ongoing renovations at the health center created logistical disruptions that interfered with vaccination services, even though vaccine supplies and cold chain equipment remained functional.
• Poor Integration of Services: Curative (treatment-focused) and preventive (vaccination) services were not well-integrated, meaning a child might visit for a sick visit without receiving due vaccines.
• Parental Misinformation: While most mothers relied on health workers for vaccine information, low literacy rates and unclear communication contributed to confusion about vaccination schedules and importance.

What Did the Data Actually Show About Vaccination Rates?

The study revealed a clear pattern of drop-out as children progressed through their vaccination series. For the pentavalent vaccine series (which requires three doses), coverage declined at each stage. Among children aged 0 to 11 months, 16.58% had not received their third dose, compared to just 3.7% who had missed the first dose. This suggests that children were starting their vaccination series but not completing it.

The age breakdown showed that younger children (0 to 11 months) had higher rates of incomplete vaccination than older children (12 to 59 months), which makes sense because older children had more time to catch up on missed doses. However, the persistence of unvaccinated children in both age groups indicates that the problem isn't simply a matter of time—it's a systemic issue that needs intervention.

What Solutions Did Researchers Recommend?

The study was led by Moussa Kaloga, a fellow in the Sabin and World Health Organization's COVID-19 Recovery for Routine Immunization Fellowship Program. His team didn't just identify problems; they developed actionable recommendations to address them. The project aimed to generate evidence for local strategies that would improve vaccine coverage and service delivery by identifying zero-dose and under-vaccinated children and recommending systemic improvements.

Key recommendations focused on three areas: better informing caregivers about vaccination importance and schedules, consistently monitoring child immunization status, and strengthening follow-up mechanisms across health services. The researchers also emphasized the need to address health worker knowledge gaps through targeted training on correct vaccine contraindications and complete immunization schedules.

Importantly, the study found that vaccine supply was not the bottleneck. The health center had adequate stocks of all vaccines, functional cold chain equipment (including two refrigerators, one solar-powered), and no reported stockouts. This means the solution isn't about getting more vaccines to the clinic—it's about ensuring they're actually given to the children who need them.

The findings from Mali highlight a challenge that extends far beyond one health area. When health workers lack correct knowledge about vaccines and when parents don't fully understand why vaccination matters, children slip through the cracks. The good news is that these barriers can be addressed through focused training, clearer communication, and better integration of vaccination services into routine health care. For parents and health officials alike, this research underscores an important truth: having vaccines available is only half the battle. Making sure every child actually receives them requires attention to the human factors that drive health care decisions.