Booster doses of measles vaccine associated with lower rates of hospital admission
Within a randomised trial of measles vaccine (MV) at 4½ and 9 months versus at 9 months only, boosting with MV reduced the risk of hospital admissions between 9-18 months among children who had not received vitamin A at birth
Background: Two doses of measles vaccine (MV) may reduce non-measles mortality more than a single dose. The effect of two versus one dose on morbidity has not been examined. Within a randomised trial of the mortality effect of two doses versus one dose of MV in Guinea-Bissau, we investigated the effect on hospital admissions.
Methods: Children were randomised 1:2 to receive MV at 4.5 and 9 months of age or the currently recommended dose at 9 months. We compared hospital admission rates between 9 and 18 months in a Cox regression model with age as underlying timescale. Half the children had received neonatal vitamin A supplementation (NVAS) in other trials. The beneficial effect of MV at 4.5 and 9 months on mortality was limited to children who had not received NVAS; we therefore investigated interaction with NVAS.
Results: Among 5626 children (two doses of MV: 1960 children, one dose of MV: 3666), 311 hospital admissions were identified between 9 and 18 months. Overall, two doses of MV compared with one dose reduced the risk of hospital admission for children who had not received NVAS (Hazard ratio (HR)=0.66 (95 % CI 0.47-0.93)) whereas there was no effect among NVAS-recipients (HR=1.16 (0.82-1.63)) (p=0.02 for interaction).
Conclusions: The benefit of two doses of MV was limited to children who had not received NVAS. NVAS is not generally recommended. Hence, an early two dose measles vaccination policy may reduce hospital admissions more than the current policy of providing the first MV at 9 months of age.
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