Low antibody response in infants with measles and children with subclinical measles virus infection

During a measles epidemic (December 1979-March 1980) in two adjacent villages in Tamil Nadu, 78 of 143 under-fives were affected, eight of whom died, giving an attack rate of 54% and case-fatality rate of 10%. Seven months later 72 children (41 with measles, seven with history of measles in prior epidemics and 24 with no history of measles) were bled to measure measles virus haemagglutination-inhibition antibody. Of the 48 with measles history, 46 had measurable antibody. Surprisingly, of the 24 without a history, 16 had measurable antibody indicating the frequency of subclinical measles during epidemics. The geometric mean antibody titre was lower in infants with measles than in older children (P < 0.05). The mean titre was lower in those with subclinical measles than in those with clinical measles (P < 0.01).