Response to an extra dose of hepatitis B vaccine and specific antibody persistence in non-responders to primary immunization.
BACKGROUND
In a campaign to vaccinate health care workers, a three-dose schedule (0, 1, and 6 months) and a four-dose schedule (0, 1, 2, and 14 months) with hepatitis B (HB) vaccine were used. After primary immunization 26 subjects vaccinated with the 3-dose schedule and 4 subjects vaccinated with the 4-dose schedule had undetectable anti-HBs titres.


METHODS
All these 30 non-responders received an extra dose of the same vaccine 2 months after primary immunization and a booster dose with a yeast-derived vaccine 6 years later. Anti-HBs levels were evaluated 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 vaccinated with the 3-dose schedule became positive for anti-HBs. Six years later only two of these subjects had detectable anti-HBs. After the booster dose the seven subjects who responded to the extra dose showed an anamnestic type of response, and five additional subjects became positive for anti-HBs. Responders to the extra dose were significantly younger than the non-responders. In the four-dose group only one subject responded to the extra dose, and that subject maintained protective anti-HBs.


CONCLUSIONS
About 25% of non-responders to primary HB vaccination could benefit from an extra dose, and these subjects show an anamnestic type of response to HBs antigen even after 6 years. This response seems to be influenced by age.
Chiaramonte
M
M
Institute of Hygiene, University of Padua, Italy.
Ngatchu
T
T
Majori
S
S
Baldo
V
V
Moschen
M E
ME
Renzulli
G
G
Trivello
R
R
D000328:Adult; D005260:Female; D006282:Health Personnel; D006509:Hepatitis B / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000032:analysis* / Q000096:biosynthesis; D017325:Hepatitis B Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012044:Regression Analysis; D014611:Vaccination
D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines