Revaccination of non- and low- responders after a standard three dose hepatitis B vaccine schedule

Guangdong province of China is HBV high endemicity and 1.6 million neonates are administrated 5 μg yeast recombinant anti-HBV vaccine each year. But few studies are performed to evaluate the immunogenicity and revaccination effect on non- and low- responders.

2,199 children were administered intramuscularly with 5 μg vaccine at 0, 1 and 6 mo after birth. A 3 ml blood sample was drawn from each infant 1 mo after the third dose for determination of anti-HBs level. Three additional doses (10 μg each) were given to non- and low- responders.

Of 1,814 subjects, 3.1% were non-responders (anti-HBs titer < 10 mIUml (-1) ) and 28.9% were low-responders (anti-HBs ≥ 10 mIUml (-1) and < 100 mIUml (-1) ). Low birth weight (LBW) was a risk factor for non- and low- responders (RR = 1.6, 95%CI = 1.2-2.0). After revaccination, of the 34 non-responders, 14.7% became low-responders and 85.3% became responders. Of the 74 low-responders, 21.6% remained at the same level and 78.4% shifted into responder category.

Based on the lower responding rate after the primary immunization cycle and the higher responding rate after the additional cycle, measurement of anti-HBs level should be considered for people who had been immunized with three-dose 5 μg HB vaccine in Guangdong, especially for specific populations including LBW infants, healthcare workers, and patients with immunodeficiency disorders. An amount of 10 μg vaccine should be revaccinated to any non- and low- responders to provide adequate seroprotection.