A 7-YEAR FOLLOW-UP OF NEWBORNS VACCINATED AGAINST HEPATITIS-B

Of 79 children born to asymptomatic HBsAg chronic carrier mothers and vaccinated at birth against hepatitis B, a total of 71, 66 and 56 coul d be serologically assessed after 1, 5 and 7 years, respectively. Anti -HBs titres (geometric means) of responders decreased from 2475 to 143 IU l-1 between 1 and 5 years of age and dropped to 82 IU l-1 by 7 yea rs. At this time, a booster dose given to 34 children who showed anti- HBs titres lower or slightly higher than 100 IU l-1 significantly incr eased titres from 34 to 2985 IU l-1 (p < 0.001). Children whose titres following perinatal vaccination reached 100 to 1000 IU l-1 or above 1 000 IU l-1 maintained protective levels (> 10 IU l-1) for 3 and 5 year s, respectively. As in adults, anti-HBs titres recorded after the init ial vaccination indicate the time at which infants should receive boos ter vaccination.