This trial assessed the effect of
vitamin A on reversing
measles-induced unresponsiveness to recall
antigens and on enhancing
measles antibody production. These assessments were part of a randomized, double-masked clinical trial of the efficacy of 210 mumol of
retinol as
retinyl palmitate for reducing
measles-associated morbidity. Two hundred children between 5 mo and 17 y of age with acute
measles were enrolled at the Urban Health Centers in Ndola, Zambia; 110 subjects received a placebo and 90 received
vitamin A. At enrollment and 2 wk later, blood samples were collected to determine
measles hemagglutinin antibody titer and, at 1 and 2 wk post-enrollment, cutaneous delayed-type
hypersensitivity tests (DTH) for seven
antigens were applied. Both groups of subjects showed marked DTH unresponsiveness, but
vitamin A-treated subjects had a significant prolongation of unresponsiveness to
tuberculin [odds ratio (OR) 3.22 and 95% confidence interval (CI) 1.27-8.2], Candida (OR 5.43, CI 1.13-25.9) and Proteus (OR 5.17, CI 1.14-28.4), after adjustment for previous vaccination and age. DTH unresponsiveness was
antigen specific, reflecting prior vaccination history, and was not associated with acute respiratory
infection status. In addition, children in both treatment groups showed a significant increase in
measles antibody titer from baseline to wk 2, but this increment was not significantly different between the groups (P = 0.25). These results indicate that a single oral dose of 210 mumol of
retinol as
retinyl palmitate in oil does not enhance the immune system during
measles.