Evolution of pneumococcal serotype epidemiology in Botswana following introduction of 13-valent pneumococcal conjugate vaccine

Pneumococcal conjugate vaccines reduce the burden of invasive pneumococcal disease, but the sustained effect of these vaccines can be diminished by an increase in disease caused by non-vaccine serotypes. To describe pneumococcal serotype epidemiology in Botswana following introduction of 13-valent pneumococcal conjugate vaccine (PCV-13) in July 2012, we performed molecular serotyping of 268 pneumococcal strains isolated from 221 children between 2012 and 2017. The median (interquartile range) age of the children included in this analysis was 6 (3,12) months. Fifty-nine percent of the children had received at least one dose of PCV-13 and 35% were fully vaccinated with PCV-13. While colonization by vaccine serotypes steadily declined following PCV-13 introduction, 25% of strains isolated more than 3 years after vaccine introduction were PCV-13 serotypes. We also observed an increase in colonization by non-vaccine serotypes 21 and 23B, which have been associated with invasive pneumococcal disease and antibiotic resistance in other settings.

Pneumococcal Serotype Identification by Capsular Sequence Typing (CST): A Modified Novel Approach for Serotyping Directly in Clinical Samples

As almost 60–70% of Invasive Pneumococcal Disease (IPD) is identified by nonculture methods in Greece, serotyping is of high importance for the better monitoring of pneumococcal serotypes due to the availability of conjugate vaccines. The aim of the study was the modification and direct application of the Capsular Sequence Typing (CST) assay in clinical samples in order to serotype Streptococcus pneumoniae culture-negative, Polymerase Chain Reaction (PCR_-positive samples, followed by CST group specific single-tube PCR assays. A two-step PCR modified assay was applied on a total of 306 samples (such as CSF, blood, pleural and middle ear fluids, isolates) obtained from 283 patients with IPD. The overall performance permits a rapid, accurate and cost-effective method for nonculture pneumococcal serotyping. As the management of IPD is closely related to the continuous monitoring of pneumococcal serotypes, the proposed approach proved to be a valuable tool for the typing and epidemiological monitoring of S. pneumoniae, for the evaluation of the overall impact of vaccination programs in the era of pneumococcal conjugate vaccines, in order to initiate the appropriate vaccination strategy.

Pneumococcal serotypes causing non-invasive pneumonia in adults from a South Indian tertiary care hospital and the impact of the newer conjugate vaccines

Background. Streptococcus pneumoniae is the leading cause of community-acquired pneumonia (CAP) in adults. Ageing, chronic conditions and comorbidities are important risk factors for pneumococcal pneumonia. Purpose. There is lack of data on the pneumococcal serotypes causing non-invasive pneumonia in India. This study aims to determine the prevalent pneumococcal serotypes causing non-invasive pneumonia, the associated comorbidities, and the coverage of both the available pneumococcal vaccines in India and conjugate vaccines that are currently undergoing clinical trials. Methods. A total of 280 subjects (aged >16 years) who had clinical symptoms correlating with radiological findings for non-invasive bacteremic pneumonia and microbiological evidence of S. pneumoniae between 2018 and 2020 were included. The clinical, demographic, radiological and microbiological findings were retrieved from the Hospital Information System (HIS). Results. The common serotypes in order of prevalence were 19F, 9V, 23F, 6B, 11A, 13, 34, 10A, 19A and 6A. The predominant non-vaccine serotypes were 13, 34, 35B, 31 and 16F. The associated radiological findings were pneumonic consolidation and multi-lobar involvement. Other coinfected bacterial pathogens included H. influenzae, S. aureus, K. pneumoniae and P. aeruginosa. Conclusion. The pneumococcal vaccines: PCV10/GSK, PCV10/SII, PCV13, PCV15, PCV20 and PPSV23 provide an overall serotype coverage of 36, 41, 47, 48, 61 and 69 %, respectively of S. pneumoniae causing non-invasive pneumonia in South India. Increasing catch-up vaccination using PCV10(SII) in pre-school children could have a more significant impact on reducing pneumococcal pneumonia in adults (>50 years) in terms of increased herd immunity at an affordable cost.

If Not Now, When? Nonserotype Pneumococcal Protein Vaccines

The sudden emergence and global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have greatly accelerated the adoption of novel vaccine strategies, which otherwise would have likely languished for years. In this light, vaccines for certain other pathogens could certainly benefit from reconsideration. One such pathogen is Streptococcus pneumoniae (pneumococcus), an encapsulated bacterium that can express >100 antigenically distinct serotypes. Current pneumococcal vaccines are based exclusively on capsular polysaccharide—either purified alone or conjugated to protein. Since the introduction of conjugate vaccines, the valence of pneumococcal vaccines has steadily increased, as has the associated complexity and cost of production. There are many pneumococcal proteins invariantly expressed across all serotypes, which have been shown to induce robust immune responses in animal models. These proteins could be readily produced using recombinant DNA technology or by mRNA technology currently used in SARS-CoV-2 vaccines. A door may be opening to new opportunities in affordable and broadly protective vaccines.