eng Science and Education Publishing American Journal of Clinical Medicine Research 2328-403X 2018-01-23 6 1 5 9 10.12691/ajcmr-6-1-2 AJCMR2018612 article Faiz Mohammed alruwaili 1 Abdullah Abdulrahman muharib 1 Turki seran alharbi 1 Abdulrhman Alnasser 1 Areej Abdullatif Madani 1 Esam Albanyan 2 Mohammed Alshaalan 2 Bassam Ahmed Almutlaq 3 Hussain Gadelkarim Ahmed hussaingad5@gmail.com 3 King Saud Bin Abdulaziz University for Health Sciences, College of Medicine Pediatric Infectious Diseases, King Abdullah Specialist Children's hospital, King Abdulaziz Medical City, Riyadh University of Hail, College of Medicine Background: Invasive Pneumococcal Disease (IPD) is a life-threatening disease, which could be prevented by vaccination using Pneumococcal Conjugated Vaccine (PCV). Therefore, the aim of this study was compare the incidence before and after the introduction of the vaccine among children in King Abdulaziz Medical City (KAMC), Riyadh, Saudi Arabia, and to determine the extent of the disease prevention by the vaccine. Methodology: A retrospective cohort study including all children who are ≤ 14 years of age and microbiologically confirmed as infected (cases) with Streptococcus pneumonia (SP) from a sterile body fluid (blood or cerebrospinal fluid) before the introduction of the pneumococcal conjugated vaccine between the years of 2004-2008 and after the introduction of the pneumococcal conjugated vaccine (2009-2015) in KAMC, Riyadh, Saudi Arabia. Results: Out of 171 retrieved cases, 131/171(76.6%) were not vaccinated and 40/171(23.4%) were vaccinated. Streptococcus Pneumonia was isolated from blood in 163/171(95%) of the cases, and from cerebrospinal fluid in 23/171(13.5%) of the cases. Conclusion: The introduction of PCV7 has significantly decreased the incidence rates of IPD in children. The conjugate vaccines have shown a significant efficacy in reducing IPD among our population. http://pubs.sciepub.com/ajcmr/6/1/2/ajcmr-6-1-2.pdf Invasive Pneumococcal Disease Streptococcus pneumonia Saudi Arabia vaccine