Decreasing incidence and changes in serotype distribution of invasive pneumococcal disease in persons aged under 18 years since introduction of 10-valent and 13-valent conjugate vaccines in Portugal, July 2008 to June 2012

• Published in: Euro surveillance : bulletin européen sur les maladies transmissibles Vol. 19; no. 12; p. 20750
• Main Authors: Aguiar, Sandra, Brito, M. J., Horacio, A. N., Lopes, J. P., Ramos de Almeida Ramirez, Mário Nuno, Melo Cristino, José
• Format: Journal Article
• Language: English
• Published: Sweden European Centre for Disease Prevention and Control 27.03.2014; Centre Europeen pour la Surveillance Epidemiologique du SIDA (European Centre for the Epidemiological Monitoring of AIDS)
• Subjects: Adolescent; Bacterial infections; Child; Child, Preschool; Children & youth; Female; Humans; Immunization; Incidence; Infant; Male; Microbial Sensitivity Tests; Pneumococcal Infections - epidemiology; Pneumococcal Infections - immunology; Pneumococcal Infections - prevention & control; Pneumococcal Vaccines - immunology; Population Surveillance; Portugal - epidemiology; Serotyping; Streptococcus pneumoniae - classification; Streptococcus pneumoniae - immunology; Streptococcus pneumoniae - isolation & purification; Vaccines; Vaccines, Conjugate - immunology; Portugal
• ISSN: 1560-7917; 1025-496X; 1025-496X; 1560-7917
• DOI: 10.2807/1560-7917.es2014.19.12.20750

Eurosurveillance. © 2007 - 2021. All rights reserved The 10-valent pneumococcal conjugate vaccine (PCV10) became available in Portugal in mid-2009 and the 13-valent vaccine (PCV13) in early 2010. The incidence of invasive pneumococcal disease (IPD) in patients aged under 18 years decreased from 8.19 cases per 100,000 in 2008–09 to 4.52/100,000 in 2011–12. However, IPD incidence due to the serotypes included in the 7-valent conjugate vaccine (PCV7) in children aged under two years remained constant. This fall resulted from significant decreases in the number of cases due to: (i) the additional serotypes included in PCV10 and PCV13 (1, 5, 7F; from 37.6% to 20.6%), particularly serotype 1 in older children; and (ii) the additional serotypes included in PCV13 (3, 6A, 19A; from 31.6% to 16.2%), particularly serotype 19A in younger children. The decrease in serotype 19A before vaccination indicates that it was not triggered by PCV13 administration. The decrease of serotype 1 in all groups, concomitant with the introduction of PCV10, is also unlikely to have been triggered by vaccination, although PCVs may have intensified and supported these trends. PCV13 serotypes remain major causes of IPD, accounting for 63.2% of isolates recovered in Portugal in 2011–12, highlighting the potential role of enhanced vaccination in reducing paediatric IPD in Portugal. S.I. Aguiar and A.N. Horácio were supported by grants SFRH/BPD/78376/2011and SFRH/BD/81205/2011, respectively, from Fundação para a Ciência e Tecnologia, Portugal. This work was partially supported by Fundação para a Ciência e Tecnologia, Portugal (PTDC/DTP-EPI/1759/2012) and unrestricted research grants from Pfizer and GlaxoSmithKline.