Vaccination coverage and timeliness in three South African areas: a prospective study

Abstract

Background: Timely vaccination is important to induce adequate protective immunity. We measured vaccination timeliness and vaccination coverage in three geographical areas in South Africa.

Methods: This study used vaccination information from a community-based cluster-randomized trial promoting exclusive breastfeeding in three South African sites (Paarl in the Western Cape Province, and Umlazi and Rietvlei in KwaZulu-Natal) between 2006 and 2008. Five interview visits were carried out between birth and up to 2 years of age (median follow-up time 18 months), and 1137 children were included in the analysis. We used Kaplan-Meier time-to-event analysis to describe vaccination coverage and timeliness in line with the Expanded Program on Immunization for the first eight vaccines. This included Bacillus Calmette-Guérin (BCG), four oral polio vaccines and 3 doses of the pentavalent vaccine which protects against diphtheria, pertussis, tetanus, hepatitis B and Haemophilus influenzae type B.

Results: The proportion receiving all these eight recommended vaccines were 94% in Paarl (95% confidence interval [CI] 91-96), 62% in Rietvlei (95%CI 54-68) and 88% in Umlazi (95%CI 84-91). Slightly fewer children received all vaccines within the recommended time periods. The situation was worst for the last pentavalent- and oral polio vaccines. The hazard ratio for incomplete vaccination was 7.2 (95%CI 4.7-11) for Rietvlei compared to Paarl.

Conclusions: There were large differences between the different South African sites in terms of vaccination coverage and timeliness, with the poorer areas of Rietvlei performing worse than the better-off areas in Paarl. The vaccination coverage was lower for the vaccines given at an older age. There is a need for continued efforts to improve vaccination coverage and timeliness, in particular in rural areas.

Trial registration number: ClinicalTrials.gov: NCT00397150.

Figure 1

Time when receiving vaccines given in the four first vaccination visits for each site presented with inverse and cumulative Kaplan-Meier plots . In the first vaccination visit, an oral polio vaccine (polio0) is given together with the BCG vaccine, in the second, third and fourth vaccination visits, pentavalent vaccines are given together with polio vaccines. (Larger versions of the graph images are available as additional files 3, 4, 5, 6, 7, 8, 9 and10.) ¹ The blue vertical lines indicate the recommended age for vaccination (overlapping with red lines at birth for BCG and first polio vaccine), while the red lines indicate the outer ranges for the recommended age. The horizontal dotted lines represent coverage at end of follow-up. ² The labels on the x-axis indicate the outer ranges for recommended vaccination age. One year of age is indicated as a scaling, but is also the upper recommended age for the measles vaccine. ³ Blue graphs line: Paarl; green graph line: Umlazi; red graph line: Rietvlei.

Figure 2

Cumulative incomplete vaccination and untimely vaccination from birth to 6 months of age (including vaccination with BCG, 4 doses of oral polio vaccines, and 3 doses of pentavalent vaccines) . ¹ Coverage: The line drops represent the proportion that has got all the vaccines to that point, but does not get the given vaccine (e.g. if a child get all vaccines except the last pentavalent vaccine, the child will add to the line drop at polio3/DTP3) ² Timeliness: The line drops represent the proportion that has got all the vaccines to that point within their recommended time ranges, but does not get the given vaccine within the recommended range (e.g. if a child get all vaccines within recommend time except the DPT3 vaccine, the child will add to the line drop at third pentavalent) ³ Measles vaccine and booster vaccination not included due to sub-optimal data quality

Figure 3

Time when receiving the measles vaccine and booster vaccination with measles, DPT and oral polio presented with histogram (must be interpreted with caution) . ¹ The blue vertical lines indicate the recommended age for vaccination, while the red lines on the measles vaccine indicate the outer ranges for the recommended age. ² When the booster vaccine against measles was given at different time from the booster against polio and DPT (3 cases), the time of the measles booster will be presented.