Serotype distribution and antimicrobial resistance patterns of Streptococcus pneumoniae isolated from children in China younger than 5 years

Immunogenicity and safety of 13-valent pneumococcal conjugate vaccine in infants and toddlers

BACKGROUND

7-Valent pneumococcal conjugate vaccine (PCV7 [Prevnar, Wyeth Pharmaceuticals Inc, Philadelphia, PA], serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F) is effective in preventing vaccine-serotype pneumococcal disease. 13-Valent pneumococcal conjugate vaccine (PCV13) (PCV7 serotypes plus 1, 3, 5, 6A, 7F, and 19A) was designed to provide broader pneumococcal disease coverage. We evaluated the immunogenicity and safety of PCV13 compared with PCV7.

METHODS

Infants received PCV13 or PCV7 at ages 2, 4, 6, and 12 to 15 months with routine pediatric vaccinations. Pneumococcal anticapsular polysaccharide-binding immunoglobulin G responses and functional antipneumococcal opsonophagocytic activity were assessed 1 month after dose 3, before the toddler dose, and 1 month after the toddler dose. Safety and tolerability were also assessed.

RESULTS

For the 7 common serotypes, PCV13-elicited immunoglobulin G titers were noninferior to those elicited by PCV7, although PCV13 responses were generally somewhat lower. PCV13 also elicited functional opsonophagocytic activity comparable with that elicited by PCV7. For the 6 additional serotypes in PCV13, PCV13 elicited binding and functional antibody levels notably greater than those in PCV7 recipients. After PCV13 immunization, concordance between antipolysaccharide and opsonophagocytic responses was noted for all 13 serotypes. The PCV13 toddler dose resulted in higher immune responses compared with infant-series doses. Safety and tolerability were comparable; reactogenicity was generally mild.

CONCLUSIONS

PCV13 will be as effective as PCV7 in the prevention of pneumococcal disease caused by the 7 common serotypes and could provide expanded protection against the 6 additional serotypes. The PCV13 safety profile was comparable to that of PCV7.

Summary of invasive pneumococcal disease burden among children in the Asia-Pacific region

Invasive pneumococcal disease (IPD) burden is significant in the Asia-Pacific region. This review describes the epidemiology and Streptococcus pneumoniae (SP) serotype distribution of IPD in children in the Asia-Pacific region from studies published from 1999 to 2010. IPD incidence varies widely in Asia-Pacific countries depending on the method of surveillance, the population studied, and the time period. Incidences are highest for younger children, with rates near 100-200 cases per 100,000 children aged <1 or 2 years. Incidences of preventable disease are estimated to be 6-200 cases per 100,000. Heptavalent pneumococcal conjugate vaccine (PCV7) serotype coverage shows a very wide range over the Asia-Pacific region. Ten countries have high vaccine serotype coverage (>70%), and six countries have low vaccine serotype coverage (<50%). The majority of SP serotypes in children with IPD in most countries in the Asia-Pacific region are susceptible to penicillin (intermediate and resistant <50%); a few countries have SP serotypes with high level resistance to penicillin (intermediate and resistant >50%). Japan, Taiwan, and Thailand have high PCV7 serotype coverage. Countries with low pneumococcal resistance to antimicrobials have shown increasingly higher nonsusceptibility with time. National vaccination programmes that include PCV7, 10-valent pneumococcal conjugate vaccine (PCV), or 13-valent PCV would significantly affect IPD burden in children aged <5 years in the Asia-Pacific region, as well as the burden of penicillin-nonsusceptible IPD.

Serotype distribution of Streptococcus pneumoniae causing invasive disease in the Republic of Ireland

The 7-valent pneumococcal conjugate vaccine (PCV7) was included in the routine infant immunization schedule in Ireland in September 2008. We determined the serotype of 977 S. pneumoniae isolates causing invasive disease between 2000-2002 and 2007-2008, assessed for the presence of the recently described serotype 6C and determined the susceptibility of isolates during 2007-2008 to penicillin and cefotaxime. Serotype 14 was the most common serotype during both periods and 7·7% of isolates previously typed as serotype 6A were serotype 6C. During 2000-2002 and 2007-2008, PCV7 could potentially have prevented 85% and 74% of invasive pneumococcal disease in the target population (i.e. children aged <2 years), respectively. The level of penicillin non-susceptibility was 17% in 2007-2008. Ongoing surveillance of serotypes is required to determine the impact of PCV7 in the Irish population and to assess the potential of new vaccines with expanded valency.

Immunization with a combination of three pneumococcal proteins confers additive and broad protection against Streptococcus pneumoniae Infections in Mice

Pneumococcal polysaccharide-based vaccines are effective in preventing pneumococcus infection; however, some drawbacks preclude their widespread use in developing and undeveloped countries. Here, we evaluated the protective effects of ATP-dependent caseinolytic protease (ClpP), pneumolysin mutant (DeltaA146 Ply), putative lipoate-protein ligase (Lpl), or combinations thereof against pneumococcal infections in mice. Vaccinated mice were intraperitoneally and/or intranasally challenged with different pneumococcal strains. In intraperitoneal challenge models with pneumococcal strain D39 (serotype 2), the most striking protection was obtained with the combination of the three antigens. Similarly, with the intranasal challenge models, (i) additive clearance of bacteria in lungs was observed for the combination of the three antigens and (ii) a combination vaccine conferred complete protection against intranasal infections of three of the four most common pneumococcal strains (serotypes 14, 19F, and 23F) and 80% protection for pneumococcal strain 6B. Even so, immunity to this combination could confer protection against pneumococcal infection with a mixture of four serotypes. Our results showed that the combination vaccine was as effective as the currently used vaccines (PCV7 and PPV23). These results indicate that system immunization with the combination of pneumococcal antigens could provide an additive and broad protection against Streptococcus pneumoniae in pneumonia and sepsis infection models.