Vaccine 29 (2011) 5740–5746 Contents lists available at ScienceDirect Vaccine j ourna l ho me pag e: www.elsevier.com/locate/vaccine Invasive pneumococcal disease: Association between serotype, clinical presentation and lethality M a Angeles Gutiérrez Rodríguez a,* , Amai Varela González a , María Ascensión Ordobás Gavín a , Fernando Martín Martínez a , Natividad García Marín a , Belén Ramos Blázquez b , Juan Carlos Sanz Moreno b a Dirección General de Atención Primaria, Subdirección de Promoción de la Salud y Prevención, Consejería de Sanidad, Comunidad de Madrid, Spain b Dirección General de Ordenación e Inspección, Laboratorio Regional de Salud Pública, Consejería de Sanidad, Comunidad de Madrid, Spain a r t i c l e i n f o Article history: Received 6 April 2011 Received in revised form 25 May 2011 Accepted 27 May 2011 Available online 15 June 2011 Keywords: Invasive pneumococcal disease Heptavalent pneumococcal conjugate vaccine Serotype a b s t r a c t To ascertain the factors linked to invasive pneumococcal disease (IPD) caused by the different serotypes in the period 2007–2009, following the conjugate vaccine’s inclusion in the childhood vaccination schedule, a total of 2013 IPD cases were reviewed. The mean annual incidence in this period was 10.74 cases per 100,000 inhabitans and the lethality was 8.8%. Overall serotype distribution displayed certain peculiari- ties, such as the high frequency of serotype 5. Serotype 3, male gender, sepsis and presence of risk factors were significantly associated with lethality. Vaccinated children under 5 years of age had a higher risk of disease due to serotype 19A. Serotype 8 was associated with the presence of underlying risk factors. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Streptococcus pneumoniae (pneumococci) is an important cause of morbidity and mortality world-wide. Incidence of invasive pneu- mococcal disease (IPD) in industrialised countries varies widely with geographic region, with figures of 8–34 cases per 100,000 inhabitants [1]. In 2006, lethality in Europe ranged from 6.5% to 20%, depending on the particular country concerned [2]. Capsu- lar polysaccharides are the major virulence factor of pneumococci [3], with more than 90 different serotypes being identified, accord- ing to the capsule’s composition [4]. The frequency of the different serotypes varies with age, clinical presentation, time and geograph- ical region [5,6]. Only a limited number of serotypes are responsible for most cases of invasive disease across all age groups [1]. In the Madrid Autonomous Region (MAR), heptavalent pneu- mococcal conjugate vaccine (PCV7) was included in the systematic childhood vaccination schedule in November 2006, with doses at two, four, six and eighteen months of age. From 2001 to 2006, administration of PCV7 was recommended exclusively for children under the age of 2 years who belonged to high-risk groups. The * Corresponding author at: Dirección General de Atención Primaria, Subdirección de Promoción de la Salud y Prevención, C/Julián Camarillo 4b, 2 a planta, Madrid 28037, Spain. Tel.: +34 912052233; fax: +34 912040173. E-mail address: angeles.gutierrez@salud.madrid.org (M.A. Gutiérrez Rodríguez). World Health Organisation regards the introduction and mainte- nance of high PCV7 vaccination coverages in children as a matter of high priority [1]. In 2009, PCV7 coverage in the Madrid Autonomous Region (MAR) was 94.47%. Furthermore, immunisation with the pneumococcal capsular polysaccharide vaccine against the 23 serotypes that most fre- quently cause pneumococcal infection (PPV23) is administrated since 2001 to people over the age of 2 years who display risk fac- tors, following the national recommendations. This indication was expanded since 2005 for adults aged over 59 years with the PPV23 being administered jointly with influenza vaccine. On June 2010 pneumococcal conjugate vaccine against 13 serotypes (PCV13) was introduced into the MAR’s systematic child- hood vaccination schedule, replacing PCV7 which had been used until then. The aim of this study was to describe the epidemiological char- acteristics of invasive pneumococcal disease caused by the different serotypes in the MAR across the period 2007–2009; and analyse the factors linked to patient death and clinical presentation. 2. Materials and methods For study purposes, a case of IPD was defined as any disease caused by haematogenic spread of the pathogen, with compatible clinical manifestations (pneumonia, bacteraemia without focus, sepsis, meningitis, peritonitis, arthritis, etc.) and identification of 0264-410X/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2011.05.099