Response to measles vaccine in Haitian infants 6 to 12 months old. Influence of maternal antibodies, malnutrition, and concurrent illnesses.

To study the factors affecting the serologic response to measles vaccination, we evaluated 595 Haitian infants from 6 through 12 months of age, and their mothers, at the beginning of an immunization program. Thirty-four per cent of the infants had preexisting serologic evidence of measles infections by 11 months of age. Among infants more than nine months of age, those who had had measles had a significantly lower nutritional status than those who had not (P less than 0.01). After vaccination, seroconversion rates increased from 45 per cent at 6 months to 100 per cent at 12 months. The lowest rate of vaccine failure compatible with acceptably low rates of natural infections could be achieved by vaccination after eight months of age. Infants born to mothers with low levels of antibody to measles (hemagglutination-inhibition antibody titers less than 1:40) were significantly more likely to have had natural measles (P less than 0.01) or to have seroconversion after vaccination (P less than 0.001) at 6 to 10 months of age than were infants born to mothers with higher of age than were infants born to mothers with higher titers. Malnutrition and acute infections did not affect seroconversion rates. These data support the World Health Organization recommendation to administer measles vaccine in under-developed countries as soon after nine months of age as possible, regardless of nutritional status or the presence of minor illnesses.

Xerophthalmia and anterior segment blindness.

The prevalence of presumed vitamin A-related corneal scars among 5,589 preschool-age Haitian children ranged from 1.2 per 1,000 in the south, to almost 1% in the famine-afflicted north. These scars accounted for at least 45% of all corneal scars, and all bilateral corneal blindness encountered. Most lesions were acquired during the first three years of life. There was no variation by sex or ecology of the sample site. This country of 5.5 million inhabitants acquires 345 new surviving cases of vitamin A-related corneal destruction, over one fourth bilaterally blind, each year, although local ophthalmologists rarely encounter the disease and Bitot's spots were absent from our study population. Countrywide clinical prevalence surveys are the only unbiased means of determining the magnitude, severity, and geographic distribution of vitamin A-related corneal destruction, prerequisites for the design of public health prevention programs.