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 could 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 years. 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 increased 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 1000 IU l-1 maintained protective levels (> 10 IU l-1) for 3 and 5 years, respectively. As in adults, anti-HBs titres recorded after the initial vaccination indicate the time at which infants should receive booster vaccination.