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Objective Although vaccine coverage in infants in sub-Saharan Africa is high, this is estimated at the age of 6–12 months. There is little information on the timely administration of birth dose vaccines. The objective of this study was to assess the timing of birth dose vaccines (hepatitis B, BCG and oral polio) and reasons for delayed administration in The Gambia. Methods We used vaccination data from the Farafenni Health and Demographic Surveillance System (FHDSS) between 2004 and 2014. Coverage was calculated at birth (0–1 day), day 7, day 28, 6 months and 1 year of age. Logistic regression models were used to identify demographic and socio-economic variables associated with vaccination by day 7 in children born between 2011 and 2014. Results Most of the 10,851 children had received the first dose of hepatitis B virus (HBV) vaccine by the age of 6 months (93.1%). Nevertheless, only 1.1% of them were vaccinated at birth, 5.4% by day 7, and 58.4% by day 28. Vaccination by day 7 was associated with living in urban areas (West rural: adjusted OR (AOR) = 6.13, 95%CI: 3.20–11.75, east rural: AOR = 6.72, 95%CI: 3.66–12.33) and maternal education (senior-educations: AOR = 2.43, 95%CI: 1.17–5.06); and inversely associated with distance to vaccination delivery points (≧2 km: AOR = 0.41, 95%CI: 0.24–0.70), and Fula ethnicity (AOR = 0.60, 95%CI: 0.40–0.91). Conclusion Vaccine coverage in The Gambia is high but infants are usually vaccinated after the neonatal period. Interventions to ensure the implementation of national vaccination policies are urgently needed.
The Farafenni Health and Demographic Surveillance System (FHDSS) in the North Bank Region of The Gambia was established in 1981 [21]. The details of FHDSS have been described in elsewhere [21]. Briefly, the FHDSS covered all residents living in Farafenni town and surrounding villages located in North Bank Region of The Gambia. In 2012, the FHDSS covered a population of 50,455. Trained field workers visit each household every four months to collect demographic data (e.g. births, deaths, in and out migrations). Vaccination status of children under 5 years of age is collected from their infant welfare cards. If this is not available, children are considered unvaccinated. They constitute no more than 2% of children under 5 years of age [22]. For the purposes of this study, we divided the area covered by the FHDSS into four regions reflecting the catchment areas of the respective health facilities that serve the FHDSS population. These are rural west (11 villages), the catchment area of Illiasa Minor Health Centre; rural east (31 villages) served by Ngaiyen Sanjal and Sarakunda Minor Health Centres in the north and south respectively; and peri-urban (23 villages located between 5 and 10 km from the central point of the urban area) and urban areas (49 blocks) (Fig. 1). The peri-urban and urban regions access health care from a major health centre and a regional hospital located in Farafenni town. The urban area is divided into residential blocks with roughly similar number of inhabitants. Map of Farafenni. The vaccine data were collected prospectively since mid-2003 as part of routine FHDSS data collection. Socio-economic data were collected in two surveys conducted in 2007 and 2013. Place of birth is collected prospectively since January 2014, as well as other birth information such as birth weight and assistance at delivery. Health facilities within the study area are supplied with vaccines by the central medical stores in Banjul, Gambian capital, every month through the office of the Regional Health Team in Farafenni, and stored in fridges with temperature operated by solar panels. Each facility conducts reproductive and child health (RCH) clinics once or twice a week; and undertakes visits to a set schedule of outreach clinics depending on the population of the vicinity within its catchment areas on other days of the week [23]. Vaccines are administered and only available through RCH clinics and these outreach clinics (Fig. 1). Even the hospital in the study area, Farafenni Hospital, does not vaccinate children born in the hospital. Both health facilities and outreach clinics use multiple-dose vials for monovalent HBV vaccine (10 doses/vial), BCG (20 doses/vial) and OPV (20 doses/vial). As recommended by the WHO, an opened vial needs to be used within six hours for BCG and within 28 days for HBV vaccine and OPV [24]. We defined the “Birth dose” of vaccine as vaccination at the day of birth or the day after (day 0 or day 1). Vaccination coverage for the first dose of HBV vaccine, BCG and OPV at the different time points [at birth (day 0–1), day 7, day 28, 6 months and 1 year] were calculated for each year by dividing the number of vaccinated children by the number of live births. The trend of vaccine coverage over the study year was tested by trend test. Using the data from January 2011 and December 2014, factors associated with the timely administration of the first dose of vaccine [defined as vaccination at birth (day 0–1) and day 7 after birth] were identified by computing odds ratio using logistic regression. p-Value was tested using likelihood ratio tests. Children born between 2004 and 2010 were excluded from this analysis because socio-economic status (SES) was missing. The exposures of interest were area of residence (west-rural, east-rural, peri-urban and urban) and distance to vaccination delivery point (i.e. health centre or outreach clinic). We also assessed the association between the timely administration and other variables [year of birth, sex, ethnicity, season of birth, maternal age, birth spacing, presence of elder sibling(s), maternal education levels and SES]. The factors found to be associated in the univariable analysis (p < 0.2) were included in a multivariable logistic regression model. The impact of the place of birth and category of delivery assistant on vaccine coverage at birth was examined using the 2014 data as information on place of birth only collected from January 2014. All the analyses were performed using STATA 12.0. SES index were created using asset ownership and household material by principal component analysis and divided into five categories [25]. The locations of villages were mapped using Geographic Information System (GIS). We created the FHDSS map using QGIS and data of OpenSourceMap. The direct distances from villages to vaccination sites were measured using QGIS software.
