Measles vaccination of Thai infants by intranasal and subcutaneous routes: possible interference from respiratory infections.

Reactogenicity and seroresponses were studied after standard doses of Edmonston-Zagreb measles vaccine were given intranasally (i.n.) and subcutaneously (s.c.) to 6-month-old Thai children. Few children given i.n. vaccine (2/31), but most (13/21) given s.c. vaccine, seroconverted. All but 1 of 51 children were seropositive after receiving vaccine s.c. at 9 months-of-age. Upper respiratory infection (URI) outbreaks with onsets in the week following vaccination occurred after each vaccination session and were equally common in all groups. URIs following i.n. vaccination at 6 months may have adversely affected response to i.n. vaccine, while URIs after s.c. vaccination at 9 months adversely affected final geometric mean antibody titers. I.n. measles vaccination does not appear to be an acceptable route for routine vaccination.