Background

We assessed the distribution of pneumococcal serotypes in children with microbiologically confirmed invasive pneumococcal disease (IPD) before (2014-2015) and after (2016-2019) PCV10 introduction in Nepal in 2015.

Methods

Children (two months to 14 years) admitted to Patan Hospital, Nepal, with pneumococcus detected in blood, CSF or pleural fluid were included. Serotyping was by Quellung method.

Results

Among 71 IPD cases during the study period, Streptococcus pneumoniae was cultured from 57 patients (50 blood, 5 CSF, 2 pleural fluid) and 14 were only Binax-positive in CSF. The < 2 year-olds accounted for 6/20 (30%) cases in the pre-vaccine period and 7/37 (19%) cases in the post-vaccine period. Vaccine-type to non-vaccine-type IPD ratio was 5:1 in pre-vaccine and 3:4 in post-vaccine periods. In ≥2-year olds, the ratio was 13:1 pre-vaccine and 13:2 post-vaccine. Most (35/47, 74.5%) vaccine-type IPD was due to serotype (ST) 1; 3/8 among <2-year-olds (one case was vaccinated) and 32/39 among ≥2-year-olds (who were mainly unvaccinated).

Among 50 IPD cases detected from blood, 15 were in the pre-vaccine period (2014-2015) and 35 post-vaccine (2016-2019) and PCV10 serotypes were 14 pre-vaccine (9 ST1) and 27 postvaccine (22 ST1). Non-vaccine-type were 1 pre-vaccine (10A) and 8 post-vaccine (6C, 10A, 19A,14,3, 38, 41, 2). Of the 19 cases diagnosed from CSF, 5 serotyped were 1, 14, 6B, 6B and 7F. The 3 isolates from pleural fluid were serotypes 1 (n=2) and 19A.

Conclusions

Post-PCV10 introduction, IPD among <2-year-olds reduced; although a high proportion of ST1 IPD remains, most were in >4-years-olds.