Introduction Pneumococcal disease is a leading cause of morbidity and mortality in infants <3 months. Asymptomatic pneumococcal carriage is common, yet carriage is a pneumococcal disease prerequisite. Case reports suggest pneumococci may occupy maternal vaginal flora. Data documenting vertical transmission are limited. Pneumococcal carriage prevalence has been higher in indigenous Fijians (iTaukei) compared with Fijians of Indian Descent (FID). Fiji introduced ten-valent pneumococcal conjugate vaccine (PCV10) in 2012. Reported here is the association between vaginal delivery, ethnicity, and pneumococcal carriage in Fijian infants, pre- and three years post-PCV10.
Methods Annual cross-sectional carriage surveys including 5-8 week old Fijian infants were conducted, 2012-2015. Caregivers responded to demographic surveys. Nasopharyngeal swabs were taken and processed using standard methods. Multivariable logistic regression was used to investigate associations between delivery method, ethnicity, and overall, vaccine type (VT), and non-vaccine type (NVT) carriage, adjusting for demographics.
Results There were n=2,006 infants. Prevalence of overall, VT, and NVT pneumococcal carriage was 26.1% (95%CI 24.2-28.1), 6.2% (95%CI 5.2–7.3), and 20.1% (95%CI 18.3-22.0), respectively. Vaginal delivery was associated with overall (aOR 1.61, 95%CI 1.12–2.32; p=0.011) and NVT carriage (aOR 1.50, 95%CI 1.00–2.23; p=0.048), but not VT carriage (aOR 1.70, 95%CI 0.81–3.57; p=0.160). There was no association between ethnicity and carriage.
Conclusion Early pneumococcal acquisition may be associated with vaginal delivery. Mode of delivery may affect the infant microbiome. Universal prescription of antibiotics to women delivering via Caesarean section may reduce infant carriage. iTaukei ethnicity was not associated with infant pneumococcal carriage in Fiji three years post-PCV10.