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Impact of routine vaccination against Haemophilus influenzae type b in The Gambia: 20 years after its introduction

Zaman, Syed MA, Howie, Stephen RC, Ochoge, Magnus, Secka, Ousman, Bah, Alasana, Baldeh, Ignatius, Sanneh, Bakary, Darboe, Saffiatou, Ceesay, Buntung, Camara, Haddy Bah, Mawas, Fatme, Ndiaye, Malick, Hossain, Ilias, Salaudeen, Rasheed, Bojang, Kalifa, Ceesay, Samba, Sowe, Dawda, Hossain, M Jahangir, Mulholland, Kim, Kwambana-Adams, Brenda A, Okoi, Catherine, Badjie, Siaka, Ceesay, Lamin, Mwenda, Jason M, Cohen, Adam L, Agocs, Mary, Mihigo, Richard, Bottomley, Christian, Antonio, Martin and Mackenzie, Grant A (2020) 'Impact of routine vaccination against Haemophilus influenzae type b in The Gambia: 20 years after its introduction'. Journal of Global Health, Vol 10, Issue 1, e010416.

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In 1997, The Gambia introduced three primary doses of Haemophilus influenzae type b (Hib) conjugate vaccine without a boost- er in its infant immunisation programme along with establishment of a population-based surveillance on Hib meningitis in the West Coast Re- gion (WCR). This surveillance was stopped in 2002 with reported elimi- nation of Hib disease. This was re-established in 2008 but stopped again in 2010. We aimed to re-establish the surveillance in WCR and to con- tinue surveillance in Basse Health and Demographic Surveillance System (BHDSS) in the east of the country to assess any shifts in the epidemiolo- gy of Hib disease in The Gambia.
In WCR, population-based surveillance for Hib meningitis was re-established in children aged under-10 years from 24 December 2014 to 31 March 2017, using conventional microbiology and Real Time Poly- merase Chain Reaction (RT-PCR). In BHDSS, population-based surveil- lance for Hib disease was conducted in children aged 2-59 months from 12 May 2008 to 31 December 2017 using conventional microbiology only. Hib carriage survey was carried out in pre-school and school children from July 2015 to November 2016.
In WCR, five Hib meningitis cases were detected using conven- tional microbiology while another 14 were detected by RT-PCR. Of the 19 cases, two (11%) were too young to be protected by vaccination while seven (37%) were unvaccinated. Using conventional microbiology, the in- cidence of Hib meningitis per 100000-child-year (CY) in children aged 1-59 months was 0.7 in 2015 (95% confidence interval (CI)=0.0-3.7) and 2.7 (95% CI = 0.7-7.0) in 2016. In BHDSS, 25 Hib cases were report- ed. Nine (36%) were too young to be protected by vaccination and five (20%) were under-vaccinated for age. Disease incidence peaked in 2012- 2013 at 15 per 100 000 CY and fell to 5-8 per 100 000 CY over the sub- sequent four years. The prevalence of Hib carriage was 0.12% in WCR and 0.38% in BHDSS.
After 20 years of using three primary doses of Hib vaccine without a booster Hib transmission continues in The Gambia, albeit at low rates. Improved coverage and timeliness of vaccination are of high priori- ty for Hib disease in settings like Gambia, and there are currently no clear indications of a need for a booster dose.

Item Type: Article
Subjects: WA Public Health > Preventive Medicine > WA 110 Prevention and control of communicable diseases. Transmission of infectious diseases
WA Public Health > Preventive Medicine > WA 115 Immunization
WA Public Health > WA 20.5 Research (General)
Faculty: Department: Education
Digital Object Identifer (DOI):
Depositing User: Lynn Roberts-Maloney
Date Deposited: 19 Jan 2023 14:18
Last Modified: 19 Jan 2023 14:18


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