Nasopharyngeal pneumococcal carriage in Indian children following 10-valent PCV (PNEUMOSIL®) introduction through...

Reduction in the vaccine serotype (VT) carriage is a surrogate marker of pneumococcal vaccines protection. PNEUMOSIL®, a 10-valent pneumococcal conjugate vaccine (PCV) has been recently introduced in the national immunization program of India in a 2 + 1 schedule. Owing to scarcity of data about impact of PNEUMOSIL® vaccination on VT-carriage, the current study was conducted in Indian children to assess its impact.

This was a community-based cross-sectional observational study conducted between November 2022-March 2023 in rural areas of Pune, India. The study population included healthy children either fully vaccinated with PNEUMOSIL® 2 + 1 schedule through Universal Immunization Program or PCV-naïve. The vaccinated group was enrolled at least 4 months after receipt of the last PCV dose. Nasopharyngeal swabs were collected upon enrolment using World Health Organization methods in all children to isolate Streptococcus pneumoniae and identify serotypes using a Quellung test. The VT-carriage were compared between PCV-vaccinated and PCV-naïve using univariate and multivariate logistic regression.

The study enrolled 700 healthy children; 350 children aged 15-20 months previously fully vaccinated with PNEUMOSIL® 2 + 1 schedule through UIP and 350 PCV-naïve children aged 16-21 months. Overall S. pneumoniae carriage in PCV-vaccinated and PCV-naïve groups was 63·1 % (95 % CI 57·9 %-68·2 %) and 66·3 % (95 % CI 61·1 %-71·2 %), respectively (p = 0·384). VT-carriage occurred in 23·4 % (95 % CI 19·1 %-28·2 %) of vaccinated children and 30·9 % (95 % CI 26·1 %-36·0 %) of PCV-naïve participants (24·3 % reduction, p = 0·027). After adjusting for colonization risk factors, PNEUMOSIL® vaccination was associated with 32 % reduction in odds of VT colonization compared with PCV-naïve participants [OR = 0·68; 95 % CI 0·49-0·96].

The observed reduction in VT-carriage amongst Indian children was comparable to that observed with other PCVs that have demonstrated marked declines in disease transmission. These results suggest PNEUMOSIL® could be an effective public health tool in decreasing pneumococcal disease.