SEROPROTECTION RATE OF HAEMOPHILUS INFLUENZAE TYPE B CONJUGATE VACCINE AND ASSOCIATED CLINICAL OUTCOMES AMONG NIGERIAN CHILDREN AGED 6 TO 23 MONTHS.

Introduction: Haemophilus influenzae type b (Hib) causes invasive infections almost exclusively in under- fives with those aged 6-23 months being the most vulnerable. In Nigeria, it is estimated to cause nearly 400,000 annual infections and another 30,000 under-five mortality attributable to pneumonia and meningitis alone. The Hib Conjugate Vaccine (HCV) is in widespread use to combat these devastating infections. Data on its impact in Nigeria is grossly scanty. This study evaluated the seroprotection rates (SPR) of HCV and associated clinical outcomes among children aged 6-23 months in Obi L.G.A. of Nasarawa State, Nigeria. Methods: A cross-sectional study of 267 children aged 6-23 months who had completed three doses of HCV. They were enrolled via a two-staged household-level cluster sampling. Relevant sociodemographic and clinical data were obtained using structured questionnaires and serum samples collected were analysed serologically for antipolyribosylribitol phosphate (anti-PRP) antibodies using ELISA. Results: The overall SPRs against invasive Hib disease and Hib nasopharyngeal colonization were 74.2% and 26.2%, respectively. The overall geometric mean titre (GMT) of anti-PRP was 1.85 µg/mL (95%CI: 1.60-2.14) and across age groups, GMTs were >1 µg/mL-the threshold for long-term protection against invasive Hib disease. Rates/duration of healthcare admissions and average episodes of probable Hib disease syndromes were lower in seroprotected but not statistically different from non-seroprotected children. Conclusion: The demonstrated anti-PRP titres and Seroprotection Rates infer a very good HCV efficacy in Nigerian children. The lack of significant difference in clinical outcomes may be attributable to nonspecificity.

FACTORS INFLUENCING ANTI-POLYRIBOSYLRIBITOL PHOSPHATE TITRES IN YOUNG NIGERIAN CHILDREN PRIMED WITH DTWP-HEPB-HIB VACCINE.

Introduction: Recent research suggests that variation in vaccine-induced immune responses is influenced by genetic, nutritional, environmental, and vaccine-related factors, with significant vaccine design and programmatic policy implications. Haemophilus influenzae type b (Hib) Conjugate Vaccine (HCV) stimulates the production of antiPolyribosylribitol phosphate (anti-PRP) antibodies, which confer long-term protection against invasive Hib disease and nasopharyngeal colonization by Hib at titre levels ≥1µg/mL and ≥5µg/mL respectively. This study investigated the influence of these factors on the protective anti-PRP levels in children aged 6-23 months in Obi L.G.A. of Nasarawa State, Nigeria. Methods: The study was a cross-sectional, two-stage household-level cluster survey involving 267 children who had completed the E.P.I. schedule of HCV-containing DTwP-HepB-Hib. Validated questionnaires were used for enrolment and relevant clinical and laboratory evaluations including anti-PRP, ABO/Rhesus antigens, and Haemoglobin genotype assays were conducted. Regression analyses were performed using Stata to explore the correlation between sociodemographic/vaccine-related factors, nutritional status, genotype, ABO/Rhesus antigens, and protective anti-PRP titres. Results: Bivariate analysis showed that age, breastfeeding practice, household size/under-five number, nutritional, socioeconomic, Measles/Yellow fever vaccination, and Rhesus statuses were significantly associated with anti-PRP titre. However, multivariate analysis revealed that age between 6-11 months (AOR=3.12,95%CI=1.15-8.50), households with less than three under-fives (AOR=2.33,95%CI=1.14-4.78), middle socioeconomic class (AOR=3.15,95%CI=1.42-6.98), wasting (AOR=2.27,95%CI=1.23-4.22) and Measles/Yellow fever vaccination (AOR=2.90,95%CI=1.38-6.07) were significantly correlated with protective anti-PRP titres. Conclusion: Results indicate that the family and socioeconomic milieu influence anti-PRP titre, and Measles/Yellow fever vaccines may have a beneficial non-specific effect on HCV-induced seroprotection in Nigerian children.

Head Circumference of Babies at Birth in Nigeria.

BACKGROUND AND OBJECTIVES: Measuring head circumference (HC) of newborns is an important tool for evaluating intra-uterine brain development. HC reference charts currently in use in Nigeria are not representative of the local population. We thus present locally derived HC reference data for Nigerian infants at birth. SUBJECTS AND METHODS: We reviewed birth records of all infants at the Jos University Teaching Hospital (JUTH) over a 10 year period from January 2006. JUTH is a tertiary care center offering obstetric services to a large population of women in Jos and its environs. All births with gestational age between 28 and 42 weeks were included in the study. STATA version 14 was used to calculate gestational age associated HC percentile measurements. RESULTS: We included 18 282 babies to generate the reference values. The mean HC value was 34.4 ± 2.1 cm (M = 34.6 ± 2.16 cm, F = 34.1 ± 2.02 cm, p < 0.001). Our HC reference values significantly differ from the USA and INTERGROWTH-21 charts currently in use in our country. Mean HC was higher in male infants compared with female infants. This difference was uniformly so across all gestational age groups. CONCLUSIONS: The use of our locally derived HC reference values could be more appropriate in defining normal head growth in Nigerian infant populations thereby improving newborn care.

Prevalence and correlates of stunting among the school-age population in North-Central Nigeria.

INTRODUCTION: Stunting remains a huge public health concern among developing Nations. However, the burden of this problem among the school-age population appears to have been eclipsed by most nutritional surveys that focus more on the under-fives. This study aimed to demonstrate the prevalence, and identify socio-demographic factors that are associated with stunting among the school-age children in North central Nigeria. METHODS: This was a descriptive cross-sectional study that involved 450 pupils, aged 6-12 years from 10 randomly selected primary schools in Jos, Plateau state. Anthropometric indices were measured using standard techniques and the Height-for-age z-scores were generated using the WHO Anthroplus software. Socio-demographic details were obtained using semi-structured questionnaires. Data were analysed using EPI infoTM statistical software 7.1.5.2. RESULTS: The mean age of the subjects was 9.3 ± 1.8 years and the male to female ratio was 1:1.1. The prevalence of stunting was 10.5%. The prevalence of stunting was significantly higher among pupils that attended public schools (p<0.0001), those whose mothers had less than secondary level of education (p=0.0427), those between the ages of 10-12 years (p<0.0001), those from the lower socio-economic class (p=0.0021), and those whose family sizes were larger than six family members (p=0.0063). CONCLUSION: The substantial burden of stunting among the school age population has significant correlation with certain socio-demographic factors. Addressing these factors by alleviating poverty, promoting maternal literacy and encouraging family planning may, perhaps, lessen the burden of stunting among the school-age group in Northern Nigeria.