Nasopharyngeal pneumococcal carriage in South Asian infants: Results of observational cohort studies in vaccinated and unvaccinated populations

Abstract

Background Nasopharyngeal pneumococcal carriage (NPC) is a prerequisite for invasive pneumococcal disease and reduced carriage of vaccine serotypes is a marker for the protection offered by the pneumococcal conjugate vaccine (PCV). The present study reports NPC during the first year of life in a vaccinated (with PCV10) cohort in Bangladesh and an unvaccinated cohort in India. Methods A total of 450 and 459 infants were recruited from India and Bangladesh respectively within 0-7 days after birth. Nasopharyngeal swabs were collected at baseline, 18 and 36 weeks after birth. The swabs were processed for pneumococcal culture and identification of serotypes by the Quellung test and polymerase chain reaction (PCR). An identical protocol was applied at both sites. Results Prevalence of NPC was 48% in the Indian and 54.8% in the Bangladeshi cohort at 18 weeks. It increased to 53% and 64.8% respectively at 36 weeks. The average prevalence of vaccine serotypes was higher in the Indian cohort (17.8% vs 9.8% for PCV-10 and 26.1% vs17.6% for PCV-13) with 6A, 6B, 19F, 23F, and 19A as the common serotypes. On the other hand, the prevalence of non-vaccine serotypes was higher (43.6% vs 27.1% for non-PCV13) in the Bangladeshi cohort with 34, 15B, 17F, and 35B as the common serotypes. Overcrowding was associated with increased risk of pneumococcal carriage. The present PCV-13 vaccine would cover 28%-30% and 47%-48% serotypes in the Bangladeshi and Indian cohorts respectively. Conclusions South Asian infants get colonised with pneumococci early in infancy; predominantly vaccine serotypes in PCV naïve population (India) and non-vaccine serotypes in the vaccinated population (Bangladesh). These local findings are important to inform the public health policy and the development of higher valent pneumococcal vaccines.

Changes in pneumococcal serotypes distribution and penicillin resistance in healthy children five years after generalization of PCV10

“…In this study, the most commonly detected NVSs were serotypes: 6C/6D, 19B/19C, and 15B/15C. The prevalence of these serotypes follows the changes reported in studies conducted in Bangladesh [ 35 ], the Netherlands [ 36 ], and Nigeria [ 37 ] following the introduction of PCV10. Additionally, the carriage of serotype 15 is known to be more prevalent in the PCV era [ 38 ].…”

Prevalence of Pneumococcal Carriage among Jordanian Infants in the First 6 Months of Age, 2008–2016

“…This study found a carriage rate of 48% in the Indian and 54.8% in the Bangladeshi cohort at 18 weeks, which increased to 53% and 64.8%, respectively, at 36 weeks. Vaccine serotypes for the same study was higher in the Indian cohort (17.8% vs. 9.8% for PCV-10 and 26.1% vs. 17.6% for PCV-13), with 6A, 6B, 19F, 23F, and 19A as the common serotypes [34].…”

Antibiotic Resistance of Streptococcus pneumoniae in the Nasopharynx of Healthy Children Less than Five Years Old after the Generalization of Pneumococcal Vaccination in Marrakesh, Morocco

“…In Cyprus, the non-vaccine serotypes detected in a study that included 1105 healthy children, aged between 6 and 36 months, were 15A, 6C, 23B, and 15B [ 39 ]. Among Bangladeshi children, 34, 15B, 17F, and 35B were the predominant non-vaccine serotypes, accounting for 43.6% [ 40 ]. The distribution of pneumococcal non-vaccine serotypes varies across studies due to many factors, such as age, country, study period, and time of vaccine introduction.…”