Objective Mild viral illness, including that following immunization with live attenuated measles virus (LAMV), has been associated with transient decreases in haemoglobin (Hb) and cellular immune response that may persist for several weeks. In areas of intense malaria transmission, such as western Kenya, infants experience a progressive drop in Hb until age 9–10 months and one-third may have Hb < 8 g/dl. These children may be at risk of developing severe anaemia with further haematological insult. The objective of this paper was to determine if immunization with LAMV was associated with increased risk of transient anaemia and malaria infection.
Methods Data from previous cross-sectional surveys (n = 5970) and one cohort study (n = 546) conducted among pre-school children were analyzed retrospectively.
Results Measles vaccination coverage between 12 and 23 months of age ranged from 44.8% to 62.7%. Hb concentrations in children aged 6–23 months with documented measles immunization within the previous 14 or 30 days (n = 103) were similar to those with no history of measles immunization in the previous 90 days (n = 996); mean differences [95% confidence interval (CI)] by 30 days were: in cross-sectional surveys, −0.49 g/dl (−1.12, 0.14); in the cohort study, −0.032 g/dl (−0.52, 0.46). Similarly, the risk of malaria parasitemia or severe to moderate anaemia did not differ.
Conclusion These data do not suggest that the transient decrease in Hb and cellular immune response after immunization with LAMV results in clinically significant changes in the risk of subsequent severe to moderate anaemia or malaria in young children living in malaria-endemic regions.