Key pneumonia risk factors assessed during maternal postnatal interview. Key pneumonia risk factors assessed during maternal postnatal interview. EPI: Expanded Program on Immunization; PCV: pneumococcal vaccine. Percentages were calculated based on the frequencies of each risk factors with 286 as nominator. Nguyen TK Phuong et al. bmjpo 2017;1:e000155 © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.