Efeito da vacina pneumocócica conjugada na redução de sorotipos vacinais colonizadores da nasofaringe de crianças residentes no município de Goiânia, GO
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2014-04-28
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Universidade Federal de Goiás
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10-valent conjugate pneumococcal vaccine (PCV10) was introduced in the routine immunization at Goiania in June, 2010. The aims of this study were: (i) to evaluate the direct effect of PCV10 in preventing vaccine types nasopharyngeal/NP pneumococcal carriage in younger children according to different schedules; (ii) to investigate possible genetic changes that could interfere in the pneumococcal capsular typing.
Methods: A cross-sectional population-based household survey was conducted in Goiania, Brazil, from December/2010-February/2011, targeting children aged 7-18 months. To evaluate PPCV10 effectiveness/VE, NP swabs, clinical and demographic data, and vaccination dates were collected from 1,287 children during home visits. Main outcome and exposure of interest were PCV10 vaccine-type (VT) carriage and dosing schedules (3p+0, 2p+0, and one catch-up dose), respectively. Pneumococcal carriage was defined by positivity in culture after of NP secretions in enrichment broth and isolates serotyping was performed by Quellung reaction. The nontypeable isolates were processed by conventional multiplex PCR (cmPCR). Rate ratio/RR was calculated as the ratio between the prevalence of VTs carriage in children vaccinated with different schedules (exposed) and not vaccinated to PCV10 (non-exposed). Adjusted RR was estimated using Poisson regression. VE on VT carriage was calculated as 1-RR*100.
Results: The prevalence of pneumococcal carriage in a total of 1,287 children was 41.0% (95%CI: 38.4%-43.7%). Serotypes covered by PCV10 and PCV13 were 35.2% and 53.0%, respectively. Serotypes 6B (11.6%), 6A (9,8%), 23F (7.8%), 14 (6.8%), 19F (6.6%), and 19A (6,3%) were the most frequently observed. After adjusted for confounders, children who had received 2p+0 or 3p+0 dosing schedule presented a significant reduction on pneumococcal VT carriage, with PCV10 VE equal to 35.9% (95%CI: 4.2%-57.1%; p=0.030) and 44.0% (95%CI: 14.2%-63.5%; p=0.008), respectively, when compared with unvaccinated children. For children who received one catch-up dose, no significant VE was detected (p=0.905). We identified 13 samples with a genetic variation that underestimated the capsular typing for 19F by cmPCR.
Conclusion: PCV10 was associated with high protection against vaccine-type carriage for children vaccinated before the second year of life, for 2p+0 and 3p+0 schedules. The identification of genetic variations (19Fv) allowed adapt the molecular technique (cmPCR) for capsular typing samples from Latin America. The continuous evaluation of carriage
serotype is mandatory to evaluate the long-term effectiveness and impact of pneumococcal vaccine on serotypes reduction.
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TERNES, Yves Mauro Fernandes. Efeito da vacina pneumocócica conjugada na redução de sorotipos vacinais colonizadores da nasofaringe de crianças residentes no município de Goiânia, GO. 2014. 101 f. Tese (Doutorado em Medicina Tropical e Saúde Pública) - Universidade Federal de Goiás, Goiânia, 2014.