Changes in Streptococcus Pneumoniae Carriage Show Effectiveness of PCV10


Investigators determined that the vaccination reduced the prevalence of vaccine serotypes with an effectiveness of 89.6% based on the study results.

Changes in Streptococcus pneumoniae carriage, serotype, distribution, and penicillin resistance demonstrate effectiveness of the pneumococcal conjugate vaccine 10 (PCV10), according to a study published in Heliyon. Investigators wanted to determine the “epidemiology of asymptomatic nasopharyngeal carriage of S. pneumoniae,” according to the study authors.1

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S. pneumoniae can cause community-acquired pneumonia (CAP), which is the seventh leading cause of death in the United States according to the National Library of Medicine. Further, the 30-day hospital mortality associated with CAP is approximately 22%, making it the leading cause of death among all infectious diseases.2

In the study, investigators assessed the use of PCV10 and whether it changed serotype distribution and penicillin resistance. They included 515 healthy children aged 6 to 36 months who went to vaccination clinics in Marrakesh, Morocco, between 2017 and 2018. Children with fever, respiratory symptoms, or who had antibiotics within the previous 7 days were excluded from the study. Data on demographics, risk factors for S. pneumoniae, carriage, and vaccination status were collected, the study showed. The average age was 11.7 months, with 249 males and 266 females. Approximately 35.3% were fully vaccinated.1

Investigators collected nasopharyngeal specimens and all specimens were transported to a laboratory for microbiology, according to the study authors. Serotypes were identified with real-time PCR assays, with serotype 2, 3, 4, 8, 14, and 20 exempted.1

From 2017 to 2018, there were 223 isolates collected, which equated to a nasopharyngeal carriage rate of approximately 43.4%. Approximately 52% were male and 53.4% were less than 12 months old, according to the study authors.1 The investigators found that age between 6 to 12 months and complete vaccination status were risk factors for carriage, but previous antibiotic therapy had a significant protective effect against S pneumoniae, according to the study authors.1

Being male and having a sibling were not statistically significant for the rate of carriage among healthy individuals.1

Key Takeaways

  1. The study demonstrates the effectiveness of the pneumococcal conjugate vaccine 10 (PCV10) in reducing nasopharyngeal carriage of Streptococcus pneumoniae among healthy children aged 6 to 36 months in Marrakesh, Morocco.
  2. Comparison of serotype distribution before and after PCV10 introduction revealed a decrease in vaccine serotypes and a concurrent rise in non-vaccine serotypes.
  3. The study also assessed antibiotic resistance among pneumococcal isolates, revealing concerning levels of resistance to penicillin G, amoxicillin, cefotaxime, erythromycin, clindamycin, tetracycline, and cotrimoxazole.

When the investigators compared the serotype distribution between 2008 and 2009, before vaccination, and 2017 and 2018, they found a decrease in the rate of serotypes included in PCV10 and PCV13, according to the results of the study. However, there was a significant rise in non-vaccine serotypes. To assess the effects of PCV10 on the serotype diversity in healthy children, investigators used the Simpson’s Diversity Index in 2008 to 2009 and 2017 to 2018, which showed scores of 0.844 and 0.93, respectively.1

The diversity of serotypes was also higher in 2017 than in 2018, according to the study authors. They said this indicated a low probability of carrying vaccine serotypes after the introduction of PCV10. Investigators determined that vaccination reduced the prevalence of vaccine serotypes with an effectiveness of 89.6%, according to the results.1

Investigators used 64 samples when checking for antibiotic resistance, with approximately 26.6% being pneumococci non-susceptible to penicillin G. Approximately 20% were classified as intermediate and 6.3% were resistant, according to the study authors. Furthermore, 9.4% and 12.5% were resistant to amoxicillin and cefotaxime, respectively. Resistance was also found for erythromycin (28.1%), clindamycin (14.1%), tetracycline (12.5%), and cotrimoxazole (12.5%). A low prevalence of resistance was found for chloramphenicol at 3.1%, according to the study authors.1

  1. Warda K, Amari S, Boureddane M, Elkamouni Y, et al. Changes in pneumococcal serotypes distribution and penicillin resistance in healthy children five years after generalization of PCV10. Heliyon. 2024. doi:
  2. Dion CF, Ashurst JV. StatPearls: Streptococcus pneumoniae. National Library of Medicine. Updated August 8, 2023. Accessed February 16, 2024.
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