the prevalence of antibodies against hepatitis a virus ( anti-hav ) was evaluated in sera from 275 asymptomatic infants and children under the age of five years and in 46 maternal-cord serum pairs , followed by sera obtained thereafter each month from the first to the fifth month of life in 29 , 17 , 9 , 9 and 7 infants ( a total of 163 serum samples ) .
C0008059
children
C0021270
infants