Impact of the introduction of pneumococcal conjugate vaccination on pneumonia in The Gambia: population-based surveillance and case-control studies

• Published in: The Lancet infectious diseases 2017-09, Vol.17 (9), p.965-973
• Main Authors: Mackenzie, Grant A, Dr, Hill, Philip C, Prof, Sahito, Shah M, MPH, Jeffries, David J, PhD, Hossain, Ilias, MPH, Bottomley, Christian, PhD, Uchendu, Uchendu, MD, Ameh, David, MPH, Ndiaye, Malick, DP, Osuorah, Chidebereh D, MPH, Adeyemi, Oyedeji, MBBS, Pathirana, Jayani, MSc, Olatunji, Yekini, MBChB, Abatan, Bade, MBChB, Ahameefula, Ebirim, MBBS, Muhammad, Bilquees S, MBBS, Fombah, Augustin E, MD, Saha, Debasish, PhD, Mackenzie, Roslyn, FRACGP, Plumb, Ian, MBBS, Akano, Aliu, FMCR, Ebruke, Bernard, FWACP, Ideh, Readon C, FWACP, Kuti, Bankole, FWACP, Githua, Peter, MSc, Olutunde, Emmanuel, MBChB, Ofordile, Ogochukwu, MBBS, Green, Edward, FRCP, Usuf, Effua, PhD, Badji, Henry, MSc, Ikumapayi, Usman N A, MSc, Manjang, Ahmad, MSc, Salaudeen, Rasheed, BSc, Nsekpong, E David, BSc, Jarju, Sheikh, DVM, Antonio, Martin, Prof, Sambou, Sana, MSc, Ceesay, Lamin, MSc, Lowe-Jallow, Yamundow, MSc, Sowe, Dawda, MSc, Jasseh, Momodou, PhD, Mulholland, Kim, Prof, Knoll, Maria, PhD, Levine, Orin S, Prof, Howie, Stephen R, PhD, Adegbola, Richard A, Prof, Greenwood, Brian M, Prof, Corrah, Tumani, Prof
• Format: Article
• Language: English
• Subjects: Age; Case studies; Charities; Children; Control methods; Criteria; Demographics; Gambia; Health; Health care facilities; Heptavalent Pneumococcal Conjugate Vaccine - administration & dosage; Hospital facilities; Hospitalization; Humans; Hypoxia; Immunization; Incidence; Income; Infant; Infectious Disease; Infectious diseases; Low income areas; Low income groups; Medical research; Pneumococcal Infections - immunology; Pneumococcal Infections - prevention & control; Pneumococcal Vaccines - administration & dosage; Pneumonia; Pneumonia, Pneumococcal - prevention & control; Population; Population Surveillance; Population-based studies; Radiology; Streptococcus infections; Streptococcus pneumoniae - immunology; Studies; Surveillance; Vaccination - methods; Vaccine efficacy; Vaccines; Vaccines, Conjugate - immunology
• ISSN: 1473-3099; 1474-4457
• DOI: 10.1016/S1473-3099(17)30321-3

Summary Background Pneumococcal conjugate vaccines (PCVs) are used in many low-income countries but their impact on the incidence of pneumonia is unclear. The Gambia introduced PCV7 in August, 2009, and PCV13 in May, 2011. We aimed to measure the impact of the introduction of these vaccines on pneumonia incidence. Methods We did population-based surveillance and case-control studies. The primary endpoint was WHO-defined radiological pneumonia with pulmonary consolidation. Population-based surveillance was for suspected pneumonia in children aged 2–59 months (minimum age 3 months in the case-control study) between May 12, 2008, and Dec 31, 2015. Surveillance for the impact study was limited to the Basse Health and Demographic Surveillance System (BHDSS), whereas surveillance for the case-control study included both the BHDSS and Fuladu West Health and Demographic Surveillance System. Nurses screened all outpatients and inpatients at all health facilities in the surveillance area using standardised criteria for referral to clinicians in Basse and Bansang. These clinicians recorded clinical findings and applied standardised criteria to identify patients with suspected pneumonia. We compared the incidence of pneumonia during the baseline period (May 12, 2008, to May 11, 2010) and the PCV13 period (Jan 1, 2014, to Dec 31, 2015). We also investigated the effectiveness of PCV13 using case-control methods between Sept 12, 2011, and Sept 31, 2014. Controls were aged 90 days or older, and were eligible to have received at least one dose of PCV13; cases had the same eligibility criteria with the addition of having WHO-defined radiological pneumonia. Findings We investigated 18 833 children with clinical pneumonia and identified 2156 cases of radiological pneumonia. Among children aged 2–11 months, the incidence of radiological pneumonia fell from 21·0 cases per 1000 person-years in the baseline period to 16·2 cases per 1000 person-years (23% decline, 95% CI 7–36) in 2014–15. In the 12–23 month age group, radiological pneumonia decreased from 15·3 to 10·9 cases per 1000 person-years (29% decline, 12–42). In children aged 2–4 years, incidence fell from 5·2 to 4·1 cases per 1000 person-years (22% decline, 1–39). Incidence of all clinical pneumonia increased by 4% (–1 to 8), but hospitalised cases declined by 8% (3–13). Pneumococcal pneumonia declined from 2·9 to 1·2 cases per 1000 person-years (58% decline, 22–77) in children aged 2–11 months and from 2·6 to 0·7 cases p