P-1471. Impact of PCV10 Introduction on Nasopharyngeal Carriage of Streptococcus pneumoniae in Healthy Children in Rural and Urban Nepal

Abstract Background The ten-valent pneumococcal conjugate vaccine (PCV10) was introduced in Nepal in 2015. We compared the nasopharyngeal carriage of PCV10and non-PCV10 serotypesof pneumococcusbetween pre-vaccine (2014-2015) and post-vaccine (2016-2019) years in two different regions of Nepal. Methods Nasopharyngeal samples obtained in healthy Nepalese children aged 6-59 months in urban (Patan, Kathmandu) and 6-23 months in rural (Okhaldhunga) settings were transported in STGG (Skim Milk-Tryptone-Glucose-Glycerol) media, cultured for pneumococcus and serotyped by the Quellung method. Results PCV10-type prevalence decreased from 27.67% in rural and 19.08% in urban children pre-vaccine to 9.73% and 9.18% post-vaccine, respectively. Pre-vaccine, the most frequently found serotypes in both settings were 19F, 6B, 14. Post-vaccine, the non-PCV10 serotypes were more common. Significant increases were observed in additional PCV13 serotypes 3, and 19A, in both settings. In addition, in the urban setting, non-vaccine serotypes 15C, 34, 13, 23B and 33B increased, whereas, serotypes 10A, 23A and 33F increased in the rural setting. The carriage prevalence has decreased for most of the PCV10-type serotypes in both the settings except 7F, 9V, 4 and 5, which did not show significant decrease. Conclusion Since the introduction of PCV10, carriage prevalence of most of the PCV10 serotypes have reduced and non-PCV10 serotypes have increased in both settings. However, due to increase in non-PCV10 serotypes, replacement disease may occur in the future. Thus continued monitoring of changes in the nasopharyngeal carriage of vaccine type pneumococcal serotypes is important when assessing vaccine impact. Disclosures All Authors: No reported disclosures