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Abstract
WHO has recommended vitamin A supplementation for children aged 6 months or older
in developing countries at the same time as immunisation. One study has reported significantly
lower seroconversion ratios among children who have received vitamin A supplements
with measles vaccine at age 6 months. The aim of our study was to assess the effect
of vitamin A supplementation on antibody response to measles vaccination at age 9
months, which is the more common age for immunisation in developing countries.
In an urban community in Guinea-Bissau, we did a randomised, double-blind, placebo-controlled
study of the effect of simultaneous vaccination and vitamin A supplementation in 462
children who received either a two-dose schedule of measles vaccine at the ages of
6 months and 9 months (150 infants) or one dose of measles vaccine at age 9 months
(312 infants). Children were followed up to the age of 18 months and a blood sample
was then collected to assess the antibody response.
397 (86%) of the children took part in the follow-up (52 [11%] had moved and 13 [3%]
had died). Among children who received a two-dose vaccine schedule, seroconversion
was 98%. There was no difference in seroconversion or geometric mean titre (GMT) for
children receiving vitamin A compared with children receiving no supplement. Among
children receiving only one dose of measles vaccine at age 9 months, seroconversion
was 95%. The GMT was significantly higher in children receiving vitamin A than in
those receiving no supplement (3704 vs 2439 mIU; GMT ratio 1.52 [1.22-1.88]). The
effect on plasma antibody concentration in the blood was stronger for boys (3902 vs
1916 mIU; GMT ratio 2.04 [1.53-2.72]) than for girls (3502 vs 3017 mIU; GMT ratio
1.16 [0.85-1.58]) who had received vitamin A with measles vaccine. In a multivariate
analysis of variance adjusted for sex, vitamin A supplementation was associated with
higher antibody titres (p < 0.001). There was a significant interaction between vitamin
A supplementation and sex (p = 0.02).
There is no indication that simultaneous administration of measles vaccine and vitamin
A supplements has a negative effect on measles immunity. Among the children who had
received two doses of measles vaccine at the ages of 6 months and 9 months, supplements
of vitamin A had no significant effect. Among children only receiving one dose of
measles vaccine at age 9 months, 100,000 IU vitamin A increased antibody concentrations,
especially for boys.