Antibody levels and immune memory 23 years after primary plasma-derived hepatitis B vaccination: Results of a randomized placebo-controlled trial cohort from China where endemicity is high

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Vaccine. 2011 Jan 27. [Epub ahead of print]

Antibody levels and immune memory 23 years after primary plasma-derived

hepatitis B vaccination: Results of a randomized placebo-controlled trial cohort

from China where endemicity is high.

Wu Q, Zhuang GH, Wang XL, Wang LR, Li N, Zhang M.

Department of Epidemiology and Biostatistics, Xi'an Jiaotong University College

of Medicine, Xi'an, Shaanxi 710061, PR China.

Abstract

The duration of protection of hepatitis B vaccine remains incompletely

understood. To assess the long-term protection provided by a primary vaccine

series, the current study again recruited all subjects of a previous randomized

placebo-controlled trial cohort 23 years after vaccination. Two hundred and

sixty-one healthy children aged 5-9 years living in a highly HBV-endemic country

were enrolled in the primary trial and received three doses of plasma-derived

vaccine or placebo. The primary placebo receivers who did not receive any

immunization against hepatitis B were used as non-vaccinated controls in the

current study. After eliminating the interference of an early booster dose and

vaccines outside the study, 48.1% (39/81) vaccinees still maintained anti-HBs

titers ™10mIU/mL at Year 23, higher than 34.7% (26/75) in non-vaccinated

controls (P=0.088). 75-100% of vaccinees with anti-HBs titer <10mIU/mL at Year

23 in different sub-groups divided according to early immune backgrounds

developed a rapid and robust antibody anamnestic response after a booster dose,

highly significantly different from non-vaccinated controls who received the

same dose of vaccine (7.5%, P<0.01). No case of clinically significant HBV

infection was found in the primary cohort during the whole 23 years, but 10

transient HBsAg seroconversions in the primary placebo group and one in the

primary vaccine group were determined. Anti-HBc positive rate obviously tended

to be lower in vaccinees compared with non-vaccinated controls at Year 23. These

results suggest a persisting immune memory and certain protection for 23 years

after primary vaccination in children living in highly HBV-endemic areas.

Clinically insignificant infections, which cannot be avoided and may often occur

in vaccinees, play a positive role in the maintaining of immunity to HBV.

Booster doses should be unnecessary for more than 20 years after a full primary

immunization in children (as catch-up vaccination) and, also likely, in newborns

living in highly HBV-endemic areas.

Copyright ¿ 2011 Elsevier Ltd. All rights reserved.

PMID: 21277403 [PubMed - as supplied by publisher]