M. Chiaramonte et al., RESPONSE TO AN EXTRA DOSE OF HEPATITIS-B VACCINE AND SPECIFIC ANTIBODY PERSISTENCE IN NONRESPONDERS TO PRIMARY IMMUNIZATION, Scandinavian journal of gastroenterology, 30(6), 1995, pp. 601-603
Background: In a campaign to vaccinate health care workers, a three-do
se schedule (0, 1, and 6 months) and a four-dose schedule (0, 1, 2, an
d 14 months) with hepatitis B (HB) Vaccine were used. After primary im
munization 26 subjects vaccinated with the 3-dose schedule and 4 subje
cts vaccinated with the 4-dose schedule had undetectable anti-HBs titr
es. Methods: All these 30 non-responders received an extra dose of the
same vaccine 2 months after primary immunization and a booster dose w
ith a yeast-derived Vaccine 6 years later. Anti-HBs levels were evalua
ted 1 month after the extra dose and after the booster dose. Results:
One month after the extra dose 26.9% (7 of 26) of the subjects vaccina
ted with the 3-dose schedule became positive for anti-HBs. Six years l
ater only two of these subjects had detectable anti-HBs. After the boo
ster dose the seven subjects who responded to the extra dose showed an
anamnestic type of response, and five additional subjects became posi
tive for anti-HBs. Responders to the extra dose were significantly you
nger than the non-responders. In the four-dose group only one subject
responded to the extra dose, and that subject maintained protective an
ti-HBs. Conclusion: About 25% of non-responders to primary HB Vaccinat
ion could benefit from an extra dose, and these subjects show an anamn
estic type of response to HBs antigen even after 6 years. This respons
e seems to be influenced by age.