Comparison of the Impact of Pneumococcal Conjugate Vaccine 10 or Pneumococcal Conjugate Vaccine 13 on Invasive Pneumococcal Disease in Equivalent Populations

Abstract

Background: Pneumococcal conjugate vaccine 10 (PCV10) and pneumococcal conjugate vaccine 13 (PCV13), are used in childhood immunization programs worldwide, but direct comparisons of impacts against invasive pneumococcal disease (IPD) in equivalent populations have not been performed. We compared the vaccines (prevaccination 2007-2009 vs postvaccination 2013-2016) in Sweden, where the 21 counties use either PCV10 or PCV13 (introduced 2009-2010).

Methods: All IPD episodes (n = 16992) were recorded in Sweden during 2005-2016. Of 14 186 isolates from 2007-2016, 13 468 (94.9%) were characterized with serotyping and 12 235 (86.2%) with antibiotic susceptibility. Poisson models assessed changes in incidence over time.

Results: Invasive pneumococcal disease incidences decreased between 2005 and 2016 in vaccinated children (by 68.5%), and in the whole population (by 13.5%), but not among the elderly (increased by 2%) due to a substantial increase in nonvaccine types (NVTs). In 2016, NVTs constituted 72% of IPD cases in the elderly. Serotype 6A declined in PCV10 and PCV13 counties, whereas serotype 19A increased in PCV10 counties. There was no effect against serotype 3. Cross-protection was found between 6B and 6A but not between 19F and 19A. Serotype 6C increased in PCV10 counties, but not in PCV13 counties, suggesting cross-protection with 6A, which is included in PCV13. In the elderly, the increase in NVTs, excluding 6C, was more pronounced in PCV13 counties.

Conclusions: The overall impact of IPD incidences was not statistically different irrespective of vaccine used. The incidence of serotypes, where the effect of the vaccines differed, will influence the cost-effectiveness of which vaccine to use in immunization programs. The dominance of NVTs suggests a limited effect of current pediatric PCVs against IPD in the elderly.

Keywords: PCV10; PCV13; invasive pneumococcal disease; pneumococcal conjugate vaccine; pneumococcal infection.

Figure 1.

Incidence of invasive pneumococcal disease by age group in Sweden during 2005–2016. A, All counties. B, Counties using only pneumococcal conjugate vaccine 10 (PCV10) or pneumococcal conjugate vaccine 13 (PCV13). Age group 0–4 years in blue; age group 5–64 years is shown in red; age group ≥65 years is shown in green; total incidence in purple. The solid line indicates counties using PCV10. The dotted line indicates counties using PCV13. Blue background indicates when PCV7 was used in the child immunization program. Yellow background indicates when PCV10 or PCV13 was used in the child immunization program. Abbreviations: PCV7, pneumococcal vaccine 7; PCV10, pneumococcal conjugate vaccine 10; PCV13, pneumococcal conjugate vaccine 13.

Figure 2.

Incidence of invasive pneumococcal disease caused by serotypes 3, 6A and 19A in counties using only pneumococcal conjugate vaccine 10 (PCV10) compared with counties using pneumococcal conjugate vaccine 13 (PCV13). A, All ages. B, Those aged ≥65 years. Serotype 3 is shown in blue; serotype 6A is shown in red; and serotype19A is shown in green. The solid line indicates counties using PCV10. The dotted line indicates counties using PCV13. Blue background indicates when PCV7 was used in the child immunization program. Yellow background indicates when PCV10 or PCV13 was used in the child immunization program. Abbreviations: PCV7, pneumococcal vaccine 7; PCV10, pneumococcal conjugate vaccine 10; PCV13, pneumococcal conjugate vaccine 13; Ser., serotype.

Figure 3.

Incidence of invasive pneumococcal disease caused by serotypes not included in any conjugated vaccines in pneumococcal conjugated vaccine 10 (PCV10) and pneumococcal conjugate vaccine 13 (PCV13) counties.