Vaccination Coverage and Compliance with Three Recommended Schedules of 10-Valent Pneumococcal Conjugate Vaccine during the First Year of Its Introduction in Brazil: A Cross-Sectional Study

<div><p>Pneumococcal 10-valent conjugate vaccine (PCV10) was introduced to Brazil’s National Immunization Program (NIP) in 2010. During the first year of vaccine introduction three schedules were used to deal with age at initiation of PCV for catch-up purposes: 3 primary doses + 1 booster (for children aged ≤6 months), a catch-up schedule of 2 doses + 1 booster (7-11 months), and a catch-up schedule of a single dose (12-15 months). The purpose of this study was to assess the magnitude and associated risk factors for under-vaccination or lack of on time vaccination six to eight months after PCV10 introduction. A household survey was conducted in the municipality of Goiania with 1,237 children, who were retroactively classified into one of three age groups, as a factor of the child’s age relatively to 30 days after PCV10 introduction. Socioeconomic characteristics and vaccination dates were obtained during home interviews. Vaccination coverage was defined as the percentage of children who completed the recommended number of doses. Compliance with recommended schedules was defined as the percentage of children who received all valid doses at the NIP recommended time interval. Adjusted prevalence ratios (PR) of variables independently associated with coverage and compliance were estimated by log binomial regression. Coverage of DTP-Hib was used for comparison purposes. Overall, vaccination coverage was 54.6% (95% CI 52.1-57.7%), lower than DTP-Hib coverage (93.0%; 95% CI 91.5-94.3%). Compliance with recommended schedules was 16.8% (95% CI: 14.7-18.6%). Children 7-11 months old had lower coverage (40.7%) and compliance (6.3%) compared to children aged 12-15 months (coverage: 88.8%; compliance: 35.6%) and ≤6 months old (coverage: 54%; compliance: 18.8%). Having private health insurance was associated with higher PCV10 coverage (PR=1.25; 95% CI: 1.06-1.47, p=0.007), and compliance (PR=1.09; 95% CI: 1.02-1.16, p=0.015). Although PCV10 coverage rapidly increased shortly after vaccination introduction, it was not matched by compliance with recommended schedules. Public initiatives should target compliance of PCV10 because of the burden of pneumococcal diseases on childhood morbidity and mortality.</p></div

Variables associated with PCV10 coverage, 6 to 8 months after its introduction.

<p>Goiania, December 2010 to February 2011.</p><p>PR: prevalence ratio; adj PR: adjusted prevalence ratio.</p><p>* The sum of individuals is not always 1,237 because there are missing answers, but that represents less than 8% of all participants.</p><p>Variables associated with PCV10 coverage, 6 to 8 months after its introduction.</p

Kaplan-Meier curves of incidence for the first dose of PCV10 after its introduction in the routine immunization program.

<p>Goiania, December 2010 to February 2011.</p

Rate ratio of PCV10 dosing schedule according to pneumococccal vaccine-type nasopharyngeal carriage.

§<p>Administered only for previously unvaccinated children who received the vaccine at 12 months of age or older.</p>†<p>Includes non-vaccine type carriage and non-carriage children.</p>‡<p>34 isolates missing Quellung reaction results: unvaccinated (n = 9), one catch-up dose (n = 8), 2p+0 (n = 6), 3p+0 (n = 11).</p

PCV10 effectiveness on pneumococcal vaccine-types carriage.

‡<p>Administered only for children 12 months of age or older.</p>§<p>Adjusted for no. of children in household, mother’s schooling, day-care attendance, and age (as continuous variable).</p>†<p>Percentage based on results of multivariate analysis. Vaccine effectiveness: (1-RR)×100.</p

Distribution of pneumococcal serotypes carriage in children 7–18 months of age. Goiania, December/2010-February/2011.

<p>Other serotypes: 9A, 9N, 10A, 15A, 17F, 18A, 20, 21, 22F, 23A, 23B, 24F, 25A, 28A, 29, 31, 33F, 34, 35F.</p

Distribution of children within age-groups according to age at enrollment and age at first dose, Goiania, Dec/2010 Feb/2011.

‡<p>That is, the age-group at the moment of nasopharyngeal specimen collection.</p>§<p>Unvaccinated children were classified according to age at PCV10 introduction into National Immunization Program.</p

Categories of exposure and outcome of interest considered for the estimation of rate ratio and vaccine effectiveness.

§<p>Administered only for children 12 months of age or older.</p>†<p>No culture for any other bacteria.</p><p>a+b+c+d  =  number of pneumococcal carriage, vaccine type and non-vaccine type.</p><p>c+d  =  number of unvaccinated children with pneumococcal carriage.</p><p>a+b  =  number of vaccinated children with pneumococcal carriage.</p

Characteristics associated with unvaccinated and vaccinated children with PCV10.

†<p>Defined as children who did not receive any dose at all (n = 96) or 1 dose before 12 months of age (n = 124).</p>‡<p>Defined as children who received 2 (n = 365) or 3 (n = 397) doses before 12 months of age or 1 cacth up dose >12 months of age (n = 291).</p