Invasive pneumococcal disease in adults caused by serotype 3 has high mortality and requires protection by vaccination

Streptococcus pneumoniae, the pneumococcus, is an opportunistic pathogen that colonizes the respiratory tract and can cause serious infections such as meningitis or pneumonia.

More than 100 pneumococcal serotypes are known, and invasive pneumococcal disease (IPD) caused by serotype 3 is linked to a high mortality rate.

IMG-20240514-WA0007 (còpia)

A recent study published in The Lancet Regional Health and coordinated by Carme Ardanuy, IDIBELL researcher and clinical microbiology specialist at Bellvitge University Hospital, has analysed the evolution of pneumococcal disease caused by serotype 3 in Spain over the last three decades (1989-2020). Among its main conclusions, it is highlighted that “Pneumococcal vaccines in children haven’t provided the expected level of herd immunity against serotype 3 in adults. Therefore, direct vaccination of adults is necessary for protection.,” says Ardanuy, also head of a CIBERES group.


Streptococcus pneumoniae, the pneumococcus, is an opportunistic pathogen that colonizes the respiratory tract and can cause serious infections such as meningitis or pneumonia. In fact, S. pneumoniae continues to be the leading cause of mortality in respiratory diseases worldwide. Currently, more than 100 distinct genetic variations known as serotypes have been described, although there are differences in invasive capacity and associated mortality between them. Invasive pneumococcal disease (IPD) caused by serotype 3 pneumococci is associated with high mortality, and although the 13-valent conjugate vaccine (PCV13) includes this serotype, its incidence remains high.


Genomic analysis

The work also carried out a whole genome sequencing study, revealing that serotype 3 pneumococci have two main lineages in our environment, and that one of them, the CC180-GPSC12 lineage, has been increasing in frequency over the years. Although both lineages were genetically homogeneous, CC180-GPSC12 presented a greater genetic diversity with more presence of prophages and mobile genetic elements. “Some of these elements confer antibiotic resistance, which is concerning,” says Dr. Ardanuy.


Clinical Data & Trends

In this regard, pneumonia was the main presentation of the disease, and more than half of the patients also had some comorbidity, with diabetes mellitus being the most frequent. Mortality at 30 days was high, with a decrease from 32.4% to 16.7% over the study period. However, no significant differences were observed in terms of the clinical characteristics of the patients and the mortality of the cases caused by both lineages.


The study revealed that the overall incidence of invasive pneumococcal disease (IPD) decreased from 21.0 to 12.9 cases per 100,000 population between the periods before and after the introduction of the PCV13 vaccine, demonstrating group protection. This is due to the fact that colonization by pneumococcus (asymptomatic carrier) is more frequent in children, and vaccination decreases the concentration of pneumococci of the serotypes included in the vaccine, so there is less transmission. However, the specific incidence of IPD caused by serotype 3, included in PCV13, remained stable, so indirect protection from childhood vaccination had no impact on IPD caused by this serotype in adults.


Moreover, the recent introduction of new (more effective) conjugate vaccines for the vaccination of the adult population will be an important tool in the control of adult pneumococcal diseases. “It is necessary to increase vaccination rates in adults to have good direct protection in risk groups such as those over 65 years of age, immunosuppressed, or patients with comorbidities to achieve the same effectiveness that has already been demonstrated in children,” concludes Dr. Ardanuy.


This study, carried out within the framework of the Pneumonia Programme of the Respiratory Diseases area of the Biomedical Research Networking Centre (CIBER) has also had the collaboration of researchers from the CIBER of Infectious Diseases (CIBERINFEC) and the Gregorio Marañón (Madrid), Donostia (Basque Country), Vall d’Hebron, Parc Taulí, Germans Trias i Pujol and Bellvitge (Catalonia) hospitals,  as well as the Pneumococcal Reference Laboratory, from the Carlos III Health Institute, and the Barcelona Supercomputing Center.



The Bellvitge Biomedical Research Institute (IDIBELL) is a biomedical research center created in 2004. It is participated by the Bellvitge University Hospital and the Viladecans Hospital of the Catalan Institute of Health, the Catalan Institute of Oncology, the University of Barcelona and the City Council of L’Hospitalet de Llobregat.

IDIBELL is a member of the Campus of International Excellence of the University of Barcelona HUBc and is part of the CERCA institution of the Generalitat de Catalunya. In 2009 it became one of the first five Spanish research centers accredited as a health research institute by the Carlos III Health Institute. In addition, it is part of the “HR Excellence in Research” program of the European Union and is a member of EATRIS and REGIC. Since 2018, IDIBELL has been an Accredited Center of the AECC Scientific Foundation (FCAECC).


Original paper:

Evolution of invasive pneumococcal disease by serotype 3 in adults: a Spanish three-decade retrospective study. Calvo-Silveria S, González-Díaz A, Grau I, Marimón JM, Cercenado E, Quesada MD, Casabella A, Larrosa N, Yuste J, Berbel D, Alonso M, Tubau F, Belman S, Cadenas-Jiménez I, Martín-Galiano AJ, Domínguez MÁ, Martí S, Liñares J, Pallarés R, Càmara J, Ardanuy C. Lancet Reg Health Eur. 2024 May 3;41:100913. doi: 10.1016/j.lanepe.2024.100913. eCollection 2024

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