|Year : 2016 | Volume
| Issue : 1 | Page : 16-23
Assessment of Vitamin A supplementation coverage and associated barriers in Sokoto State, Nigeria
Mohammed Dantani Adamu, Nasiru Muhammad
Department of Surgery, Ophthalmology Unit, Usmanu Danfodiyo University, Sokoto, Nigeria
|Date of Web Publication||6-Sep-2016|
Mohammed Dantani Adamu
Department of Surgery, Ophthalmology Unit, Usmanu Danfodiyo University, Sokoto
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aim: The aim of this study is to evaluate the Vitamin A supplement (VAS) and measles vaccination coverage in a district of Sokoto State, Nigeria.
Objectives: To determine the VAS and measles coverage in the district among children aged 6 months to 59 months and factors associated with nonuptake/poor uptake from provider's perspective.
Methodology: Mothers of children aged 6–59 months or their caretakers were interviewed for data on demography, socioeconomic status of the family, knowledge of Vitamin A, and receiving VASs and measles vaccination. Reasons for not receiving supplement and measles vaccine were sought from mothers and health care workers.
Results: A total of 900 children were enrolled from 20 clusters, of which 61.6% of children had received at least 1 dose of VAS in the past 12 months. Only 41.6% of the children received the two annual recommended doses of VAS. The measles vaccine coverage was 42.1%. After multivariate regression analysis, fathers' education (none or Islamic), mother's education (none or Islamic), mothers' occupation (manual, homemaker), and the child being female gender were found to be predictors of poor uptake of VAS. Fathers' disapproval was the most common barrier to uptake of both measles vaccine (64.8%) and VAS (69%) from both mothers' and health care workers' perspective.
Conclusion: This study showed poor coverage of both VAS and measles vaccination among children in Gwadabawa district and fathers' disapproval was the major reason for poor uptake
Keywords: Deficiency, fortification, health care, supplement, vaccine
|How to cite this article:|
Adamu MD, Muhammad N. Assessment of Vitamin A supplementation coverage and associated barriers in Sokoto State, Nigeria. Ann Nigerian Med 2016;10:16-23
|How to cite this URL:|
Adamu MD, Muhammad N. Assessment of Vitamin A supplementation coverage and associated barriers in Sokoto State, Nigeria. Ann Nigerian Med [serial online] 2016 [cited 2020 Sep 23];10:16-23. Available from: http://www.anmjournal.com/text.asp?2016/10/1/16/189803
| Introduction|| |
Vitamin A is a fat-soluble vitamin which includes retinol, retinal, retinoic acid, and retinyl esters.,, It is found as retinol in animal sources, for example, dairy products and as pro-Vitamin A precursors in plant sources, for example, vegetables (dark green leafy) and fruits (mango, carrots)., It is required in small amounts for immune function, maintaining epithelial integrity, vision, healthy growth, and reproduction. The Vitamin A working group defined Vitamin A deficiency (VAD) as liver stores below 20 μg (0.07 μmol) of retinol per gram while VAD disorder as any health and physiological consequences as a result of VAD with or without clinical evidence. The United Nations Children's Fund has adopted three strategies to achieve its long-term goal of eliminating VAD by 2010. The strategies are diversifying foods, fortifying foods and Vitamin A supplementations (VASs). High dose VAS has been shown to control xerophthalmia, prevent nutritional blindness and, reduces both severity and case fatality rate of measles and diarrhea. VAS is recommended in infants and children 6–59 months of age where VAD is recognized as a public health problem – this helps to reduce child morbidity and mortality.
There are a lot of countries that have integrated VAS in their national health policies. This has been done through the use of “special days” when VAS is combined with deworming or nutrition education; and, may also be distributed as part of the Expanded Programme on Immunization. About 77% of preschool children in more than 103 priority countries received two doses of VASs  in 2009.
In Nigeria, the VAS coverage was reported to be 78% in 2012. There is however, a wide range of variation among several states of the country. Most studies have shown that immunization coverage is generally low in Northern Nigeria.,, In Sokoto State, however, very few studies have explored the VAS coverage and factors affecting the uptake. Studies have shown a high prevalence of corneal scar as a cause of childhood blindness in this region, and most of these is said to be from measles and VAD., Measles vaccination and VAS can help to prevent this nutritional cause of childhood blindness. This study was conducted to investigate VAS and measles vaccination coverage and the factors affecting their uptake with the aim of developing recommendations to improve uptake.
The objectives of this study were to determine: The VAS and measles vaccination coverage among children aged 6 months to 59 months in a district of Sokoto State, Nigeria; educational level of the mothers and its relationship to uptake of supplements; factors associated with nonuptake/poor uptake from the caregiver's perspective; and the factors associated with nonuptake/poor uptake from providers' perspective.
| Methodology|| |
A population-based cross-sectional, mixed (quantitative and qualitative) survey was conducted in Gwadabawa Local Government Area (LGA) of Sokoto State over a 5-week period in June and July of 2012. A 2-stage cluster random sampling technique was used. Towns and villages (clusters) were selected using systematic sampling with probability proportional to size. Within each cluster, 45 children aged 6–59 months were enrolled for the study.
A focus group discussion was also held with two groups of caregivers and health workers to generate questions on barriers to uptake of VAS for the questionnaire and also to be used to corroborate findings from the quantitative survey.
Epi Info 6.04d version (United States Center for Diseases Control and Prevention) was used to calculate the sample size. A total of 900 children aged 9–59 months was obtained assuming an estimated projected study population of 142,996, an estimated proportion under 5 years of 15% of the population which was 21,000 and an expected coverage of VAS of 37% (federal government estimate). Absolute precision of 7.4%, a design effect of 5, 95% confidence interval and an additional 10% was added for expected nonresponse.
The study population was chosen by 2-stage cluster random sampling technique. A list of the towns and villages under Gwadabawa LGA was used as the sampling frame from which 20 clusters were randomly selected using systematic sampling with probability proportional to size. Within each cluster, 45 children aged between 6 and 59 months were enrolled for the study. In each of the selected cluster, the village/town center was determined with the aid of a village guide; a bottle was spun to determine the direction to follow, houses were then visited and children's caregivers/parents had questionnaire administered. Mothers/caregivers with children 6–59 months were considered eligible. Any caregiver that had more than one child eligible, the children had numbers assigned to them on pieces of paper and pooled together. One piece was drawn and enrolled in the study. The questions were targeted at the index child.
Mothers and caregivers/foster mothers of children aged 6–59 months, who lived up to 6 months in the community were included in the study.
Data collection procedure
A precoded interviewer-administered questionnaire was used to interview mothers and caregivers. A different interviewer-administered questionnaire was used to interview health care workers. The principal researcher and 3 research assistants conducted the interview - 2 of the assistants were females to facilitate access to mothers.
A focus group discussion was held with two different groups of mothers and health care workers to generate questions on barriers to uptake of VAS for the questionnaire. The discussion was transcribed, translated, and themes were generated and added to the questionnaire.
In each household, information on the study was given to all who agreed to participate and after that consent was obtained from the head of the household or his representative.
Precoded questions were asked based on the responses obtained from focus group discussion and literature review of barriers to immunization.
The questionnaire was translated into Hausa-the local language by the Principal Investigator. The three other research assistants read the translation and corrections were made and standardized. This was followed by a pilot survey that was conducted in a nearby nonselected community.
Ethical approval for the conduct of the study was obtained from London School of Hygiene and Tropical Medicine ethics and research committee and Sokoto State Ministry of Health. Individual verbal consent was obtained from heads of selected households. The provision of Helsinki Declaration was adhered to during the survey. Locking the hard copies in a safe cupboard in the office of the Principal Investigator whereas the soft copies of the data were password protected on secure computer ensured data confidentiality.
Data entry and analysis
Data were entered into Microsoft Access 2007 edition and exported into STATA version 12.1 (Statacorp, Texas USA) via STATA transfer for analysis. Analysis was performed using STATA version 12.1 software. The relationship between all the variables and uptake of VAS was analyzed using univariate regression analysis. Variables that were found to have statistical significance were further analyzed using multivariate regression analysis. The value of P < 0.05 was considered significant.
Univariate regression analysis of Vitamin A supplementation coverage
Univariate regression analysis was performed with all the variables against VAS coverage using STATA version 12 to check for the association.
For the analysis, educational status was further classified into:
- Formal: Attained primary, secondary, or tertiary education
- Islamic: Attained Islamic education
- None: No formal or Islamic education.
Occupational status was also regrouped into:
- Skilled: Civil servant and artisan
- Manual: Trader and farmer
- Unemployed: Unemployed.
Mothers' knowledge of Vitamin A natural source regrouped into:
Mothers' knowledge of VAD
| Results|| |
A total of 900 children from 19 communities were included in the study. One community had 2 clusters whereas the others had a cluster each. The response rate was 94.4% as in fifty eligible households, the heads of the households refused to participate in the study.
Age and sex distribution
The age and sex distribution are shown in [Table 1]. There were more male children in the study (60.6%) compared with the females (39.4%) with a ratio of F:M 1:1.5. The majority of the children were 24 months and less (73.1%) as shown in [Table 1].
Parents' educational status
The majority of the parents (72.1%) have Islamic education while only a few of the parents (0.6%) attained the tertiary educational level. At all levels of formal education, the fathers' percentage was higher than the mothers except for Islamic education. Only 9.65% of fathers and 14.62% of mothers did not have any form of education as shown in [Table 2].
Women who were homemakers defined as those who do not perform any form of activity to earn a living, form the majority (51.95%) of the mothers while parents that are civil servants constituted the least group 11.06% of fathers and 0.95% of mothers. Fathers who were farmers constituted the largest group with 42.82% as shown in [Table 3].
Vitamin A supplementation and measles coverage
A total of 523 mothers (61.6%) confirmed their children received VAS in the past 12 months, whereas 357 (42.05%) received measles vaccination and <10 could not confirm whether they have received either. Two doses of VAS were received by 353 (67.5%) of the 523 in the past 1 year and 171 (32.7%) received only one dose of VAS as shown in [Figure 1]. Measles vaccination is given only once.
In addition, 397 (76%) of the children received VAS at home whereas only 126 (24%) received VAS at health facility.
Health chart of Vitamin A supplementation and measles
There were poor records on the health chart as only 130 (24.5%) of the 523 children who received VAS had VAS recorded on their health charts while measles had 129 (36.1%) of the 357 recorded on their health charts. The remaining 697 (82%) of households either lost/damaged the chart beyond legibility or do not have the health chart.
Mothers' knowledge of Vitamin A
Fifty-four percent (459) of mothers correctly identified the VAS whereas 46% of the mothers could not correctly identify the VAS. Majority of the mothers 722 (85%) could not name any natural source of Vitamin A found in their environment with only 15% able to name one or more sources of Vitamin A. In addition, 736 (86.69%) of mothers could not name any adverse effect of VAD and only 12.96% could mention night blindness as a consequence of VAD.
Focus group discussion
There were 13 women in each of the two groups of women, and they were all of the reproductive age.
Themes generated by the focus group discussion held with mothers included:
- Advice from peer group
- It is free and therefore suspicious
- Don't like injection
- It is meant for family planning.
The heath workers focus group involved 12 workers. Seven were females and five were males. Themes generated by the health workers' focus group discussion included;
- Fathers' disapproval
- Suspicion by mothers of polio drops and confusing it with VAS
- Indeterminate - no reason given.
Barriers to uptake of Vitamin A supplementation and measles
The most common (69%) barrier to uptake of VAS was found to be fathers' disapproval. This is closely followed by indeterminate reasons from 44 (19.7%) mothers and then unavailability of vaccine 34 (15.2%) and advice from peers 16 (7.2%). The rest reasons constituted <1%.
Similarly, for measles vaccine, 201 (64.8%) of 310 mothers gave fathers' disapproval as the reason for not receiving measles vaccine, closely followed by dislike for injection for children 178 (57.4%), indeterminate reasons 94 (30.3%), unavailability of vaccine 19 (6.1%), and advice from peers 16 (5.2%). The other reasons constituted <1%.
Health-care workers perspective of barriers to uptake of supplement and vaccination was similar to that of mothers as fathers' disapproval (71% - 30 out of 42) and suspicion (because it is free) 19% were the most common reasons. The remaining response was indeterminate and formed 7% of the response.
As shown in [Table 4] mothers' education, fathers' education, fathers' occupation, mothers' occupation, mothers' knowledge of natural sources of Vitamin A and VAD, the gender of child, measles vaccine, correct identification, and venue supplement received have an association with VAS coverage. Sibling number and age group were not statistically significant.
|Table 4: Univariate analysis of Vitamin A deficiency coverage with all the variables|
Click here to view
Multivariate regression analysis
All the variables found to be statistically significant were entered into multivariate regression model in STATA using a forward step-wise Wald statistics. Gender, mothers' educational level, fathers' educational level and mothers' occupation were found to be statistically significant after adjustment with the multivariate analysis as shown in [Table 5].
Girls have 1.34 odds of not receiving VAS compared to boys (P < 0.06); There was increasing odds of not receiving VAS from having Islamic education (odds ratio 2.40, P < 0.015) to no education (4.80, P < 0.001) among mothers; this was similar to mothers' educational level. There was increasing odds of not receiving VAS by the children of a skilled-worker mother to been a manual worker (2.83, P < 0.001) to a homemaker (3.21, P < 0.001). Receiving VAS at clinic, receiving measles vaccination, correct identification of the supplement and knowledge of Vitamin A natural sources and deficiency were all statistically associated, but after multivariate analysis were not statistically significant.
| Discussion|| |
The overall coverage for VAS was found to be 61.6% (95% confidence interval [CI] 59.2, 64.3%) and only 67.5% of the children received the full recommended 2 doses in the past 12 months. Measles vaccine coverage was found to be 42.1% (95% CI 39.6, 45.4) among the children. The administrative VAS national coverage was 78% and 62%, respectively. This contrasts the findings of our study. However, having a disparity between field surveys and administrative figures were also seen in other studies in Guinea  and Nigeria. It was difficult to get the current administrative VAS coverage for sokoto for the study year, but coverage figures range between 37% and 70% as reported by the federal and state government. It is of interest to note that 2 weeks before our fieldwork, there was a routine National Immunization Day (NID) (with massive media campaign) in which VAS was also included. We were expecting a higher coverage rate and more awareness from the mothers because of these.
The VAS coverage of 61.6% found in our study closely resembles the low coverage that was found in South Africa  with variation from 6% to 67% across the districts. Similar low VAS coverage was found in Malawi ranging from 2.4% to 24.5% and in Kenya. However, the study in Malawi reported several missed opportunities during routine immunization while the South African study was a medically targeted Vitamin A distribution. The finding in our study was lower than that reported in Pakistan (74.8%) and Ghana (80%) where VAS was delivered alongside routine immunization.
All the variables except sibling number and age group were statistically significant after univariate analysis. The study found mothers' education, fathers' education, mothers' occupation, and sex of the child to be statistically significant determinants of coverage after multivariate regression analysis. This was similar to factors that were found in other studies., Among mothers, there was increased the likelihood of not receiving VAS if the mother had only Islamic education and the odds doubled if she has no education. The same trend was found in fathers' education, but the odds were not as notably high as that of the mothers' education. It is possible that education may make the parents more aware of the benefits and ill-effects of the VAS and therefore, the children of educated parents more likely to receive VAS. Mothers' occupation was also a determinant in receiving VAS as mothers that were homemakers were least likely to receive VAS followed by mothers that were manual workers. Mothers that had skilled jobs were more likely to have their children receive VAS. This could probably be because those with skilled jobs are more likely to be educated and aware about benefits of VAS. Girls were almost one and a half times less likely to receive VAS compared with boys in the study. This is similar to what was found in a study in Sokoto in 1991. Perhaps because boys are sent to school more than girls, they may have more access to the VAS than the girls.
The study also found the very poor knowledge of natural sources of Vitamin A and VAD among the majority of mothers even though this was not statistically significant after multivariate analysis. This could be explained by the low level of formal education among the mothers and possibly the fact that the VAS program mainly focuses on distribution during routine immunization days and not on health education for the mothers.
The most common barrier to uptake was fathers' disapproval from the mothers' and health care workers' perspective. This is unsurprising as the society is mainly a patriarchal society where males are heads of households and make decisions for the households. The possible reason for this may be connected to the widely held socio-cultural belief that the vaccines are harmful to the children and is viewed with suspicions, especially its link with western donor agencies. The next common barrier was an indeterminate reason, and this was probably because some mothers feel they may be blaming their spouses and therefore decides to say they do not know the reason why the child has not received measles vaccination or VAS.
The implication of this low level of coverage is the possibility of at-risk population for VAD in the community. There is, therefore, a need for more concerted efforts to increase coverage of VAS. To improve uptake and coverage, we recommend (1) integrating it into existing child health services at all level of health care; and (2) including it during the NIDs. This has been shown to be successful in Burkina Faso  and Sierra Leone. There is a need for a long-term, sustainable approach in the community, especially with the barriers to uptake found from the study. We recommend a food-based approach – families should be encouraged to raise poultry and indulge in home gardening to obtain their Vitamin A requirements. This has been shown to be successful in Guatemala  and Nicaragua. Use of Vitamin A fortified salt, sugar and flour are also strategies that need to be strengthened, especially with the reported corneal blindness among children in the district.
The limitations to the study include not including fathers in the focus group discussion that may have affected the findings of the study in relation to barriers to uptake of the VAS, However, including them in the same focus group may not be very helpful, as the women may not want to talk freely, especially as it affects the men. The NIDs that occurred 2 weeks before the fieldwork may have influenced responses from the mothers and may have made the coverage rate higher.
| Conclusion|| |
This study showed poor overall coverage for VAS when compared to the national coverage and set targets and that the most common barrier to the uptake of the VAS was fathers' disapproval.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Johnson EJ, Russell RM. Beta-Carotene. In: Coates PM, Betz JM, Blackman MR, Cragg GM, Levine M, Moss J, et al
., editors. Encyclopedia of Dietary Supplements. 2nd
ed. London and New York: Informa Healthcare; 2010. p. 115-20.
Coates PM. Encyclopedia of Dietary Supplements. 2nd
ed. London and New York: Informa Healthcare; 2010. p. 778-91.
Shils ME, Shike M. Modern Nutrition in Health and Disease. 10th
ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2006.
Solomons N, Bowman B. Vitamin A and carotenoids. In: Bowman BA, Russell RM, editors. Present Knowledge in Nutrition. Vol. 8. Washington DC: ILSI press; 2001. p. 127-45.
Institute of Medicine (US) Panel on Micronutrients. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. Washington DC(US): National Academies Press; 2001.
Sommer A, Davidson FR; Annecy Accords. Assessment and control of Vitamin A deficiency: The Annecy Accords. J Nutr 2002;132 9 Suppl: 2845S-50S.
WHO/UNICEF/IVACG Task Force. Vitamin A Supplements: A Guide to Their Use in the Treatment and Prevention of Vitamin A Deficiency and Xerophthalmia. Geneva: WHO Press; 1997.
World Health Organization. Guideline: Vitamin A supplementation in infants and children 6-59 months of age. Geneva: WHO Press; 2011.
UNICEF. The State of the World's Children 2011 – Executive Summary: Adolescence an Age of Opportunity. New York, USA: UNICEF; 2011.
Arevshatian L, Clements CJ, Lwanga SK, Misore AO, Ndumbe P, Seward JF, et al
. An evaluation of infant immunization in Africa: Is a transformation in progress? Bulletin of the World Health Organization 2007;85:449-57.
Yahya M. Polio vaccines – “No thank you!” barriers to polio eradication in Northern Nigeria. Afr Aff 2007;106:185-204.
Renne E. Perspectives on polio and immunization in Northern Nigeria. Soc Sci Med 2006;63:1857-69.
Muhammad N, Maishanu NM, Jabo AM, Rabiu MM. Tracing children with blindness and visual impairment using the key informant survey in a district of North-Western Nigeria. Middle East Afr J Ophthalmol 2010;17:330-4.
Muhammad N, Mansur RM, Dantani AM, Elhassan E, Isiyaku S. Prevalence and causes of blindness and visual impairment in Sokoto state, Nigeria: Baseline data for vision 2020: The right to sight eye care programme. Middle East Afr J Ophthalmol 2011;18:123-8.
Petousis-Harris H, Goodyear-Smith F, Turner N, Soe B. Family physician perspectives on barriers to childhood immunisation. Vaccine 2004;22:2340-4.
Burton A, Monasch R, Lautenbach B, Gacic-Dobo M, Neill M, Karimov R, et al.
WHO and UNICEF estimates of national infant immunization coverage: Methods and processes. Bull World Health Organ 2009;87:535-41.
Bendech MA, Cusack G, Konaté F, Touré A, Ba M, Baker SK. National Vitamin A supplementation coverage survey among 6-59 months old children in Guinea (West Africa). J Trop Pediatr 2007;53:190-6.
Adeboye M, Adesiyun O, Adegboye A, Eze E, Abubakar U, Ahmed G, et al
. Measles in a Tertiary Institution in Bida, Niger State, Nigeria: Prevalence, Immunization Status and Mortality Pattern. Oman Medical Journal 2011;26:114.
Hendricks M, Beardsley J, Bourne L, Mzamo B, Golden B. Are opportunities for Vitamin A supplementation being utilised at primary health-care clinics in the Western Cape Province of South Africa? Public Health Nutr 2007;10:1082-8.
Berger RA, Courtright P, Barrows J. Vitamin A capsule supplementation in Malawi villages: Missed opportunities and possible interventions. Am J Public Health 1995;85:718-9.
Clohossey PC, Katcher HI, Mogonchi GO, Nyagoha N, Isidro MC, Kikechi E, et al.
Coverage of Vitamin A supplementation and deworming during Malezi Bora in Kenya. J Epidemiol Glob Health 2014;4:169-76.
Bharmal FY, Omair A. Evaluation of Vitamin A supplementation in Gulshan-e-Sikandarabad. J Pak Med Assoc 2001;51:248-50.
David P. Evaluating the Vitamin A Supplementation Programme in northern Ghana: Has it contributed to improved child survival. John Snow Institute(JSI). Massachusettes. JSI working paper No.16. 2003. p. 56.
Grover DS, Pee SD, Sun K, Raju VK, Bloem MW, Semba RD. Vitamin A supplementation in Cambodia: Program coverage and association with greater maternal formal education. Asia Pac J Clin Nutr 2008;17:446-50.
Choi Y, Bishai D, Hill K. Socioeconomic differentials in supplementation of vitamin A: Evidence from the Philippines. Journal of Health, Population & Nutrition 2005;23:156-64.
Okolo S, Adeleke OA, Chukwu GA, Egbuaba NH, et al
. Immunization and nutritional status survey of children in selected rural communities of Sokoto state. Niger J Paediatr 2005;30:123-7.
Bruins M, Kraemer K. Public health programmes for Vitamin A deficiency control. Community Eye Health 2013;26:69-70.
Sesay FF, Hodges MH, Kamara HI, Turay M, Wolfe A, Samba TT, et al.
High coverage of Vitamin A supplementation and measles vaccination during an integrated maternal and child health week in Sierra Leone. Int Health 2015;7:26-31.
Phillips M, Sanghvi T, Suárez R, McKigney J, Fiedler J. The costs and effectiveness of three Vitamin A interventions in Guatemala. Soc Sci Med 1996;42:1661-8.
Ribaya-Mercado JD, Solomons NW, Medrano Y, Bulux J, Dolnikowski GG, Russell RM, et al.
Use of the deuterated-retinol-dilution technique to monitor the Vitamin A status of Nicaraguan schoolchildren 1 y after initiation of the Nicaraguan national program of sugar fortification with Vitamin A. Am J Clin Nutr 2004;80:1291-8.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
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