Sex, Pregnancy and Measles

The World Health Organization rescinded the recommendation that young children receive high-titer measles vaccine in 1992 following evidence that, in certain regions of the world, girls receiving this vaccine had increased mortality compared with those receiving standard-titer vaccines. It has been suggested that the high-titer vaccine might induce immunomodulation similar to that observed following wild-type measles virus infection. Additionally, maternal infection during pregnancy with malaria or HIV has been shown to reduce passive transfer of antimeasles antibodies to the fetus and lower the age at which infants become susceptible to measles. These data demonstrate that vaccine efficacy and adverse effects can vary between the sexes and this should be studied before new vaccines are widely used.