Magnitude of recall bias in the estimation of immunization coverage and its determinants.

OBJECTIVE: To study the magnitude of recall bias in the estimation of immunization coverage and to identify its determinants. DESIGN: A follow-up study of cohort of children for one year; followed by a cross-sectional recall survey. SUBJECTS: All live births in two contiguous PHC areas in Villupuram district, Tamil Nadu. METHODS: The prospective data collected from mothers of 774 children was considered as 'Gold Standard' and the retrospective recall data from them was compared with it. This was carried out for individual immunization schedules, namely, DPT, OPV, BCG and measles and for the combined immunization status. Measures such as sensitivity, specificity, positive and negative predictive values were computed. Logistic Regression technique was employed for evaluating the determinants of agreement. RESULTS: Less than 50% of mothers has immunization cards with them and more than 70% of the cards did not have complete information. The sensitivity of the recall method was 41.3% and the specificity was 79.5% when the complete immunization status was considered. For individual immunization schedules, the sensitivity ranged from 95% for BCG to 53% for measles vaccination and the specificity ranged from 30% for BCG to 68% for measles vaccination. Mother's age emerged out as a significant determinant in the agreement of two methods. Maintenance of immunization cards were very poor. CONCLUSIONS: Method of obtaining immunization status through recall survey is not sensitive. Proper maintenance of immunization cards and ensuring the availability of them with mothers for inspection are recommended for obtaining accurate estimation of vaccine coverages.

Effect of vitamin A supplementation to mother and infant on morbidity in infancy.

OBJECTIVES: To assess the impact of Vitamin A supplementation to the mother soon after delivery and to the infant at six months on morbidity in infancy. DESIGN: Randomized double blind placebo controlled field trial. SETTING: 51 villages in two contiguous Primary Health Centers in Villupuram Health Unit District of Tamil Nadu, South India. SUBJECTS: 909 newly delivered mother-and-infant pairs. INTERVENTIONS: Both mother and infant received Vitamin A (300,000 IU for mothers and 200,000 IU for children) in 311 instances (AA); mother received Vitamin A but infant received Placebo in 301 instances (AP); and both mother and infant received Placebo in the remaining 297 instances (PP). MAIN OUTCOME MEASURES: Incidence of diarrhea and Acute Respiratory Infection (ARI); distributions of infants by frequency of episodes and number of infected days. RESULTS: 233 in the AA Group and 228 each in the AP and PP Groups were followed up regularly. The incidence of diarrhea in these infants was 97.4%, 96.9% and 94.7% in the three groups, mean number of diarrheal episodes was 4.4, 4.6 and 4.2 and median number of days in infancy with diarrhea was 26, 26 and 22 days, respectively. For ARI, the incidences were 96.6%, 95.6% and 96.1%, means were 4.8, 5.1 and 4.8 episodes, and the medians were 32, 34 and 34 days, respectively. CONCLUSIONS: Prophylactic administration of mega doses of Vitamin A to the mother soon after delivery and to the infant at six months do not have any beneficial impact on the incidence of diarrhea and ARI in infancy.