— Christine M. Kukka, Project Manager, HBV Advocate
Is someone who has been vaccinated against
hepatitis B still protected if their hepatitis B antibody count falls
below 10 international units per milliliter (IU/ml)? Some experts fear
declining antibodies means a waning of protection while others contend
that the immune system continues to remember the virus and can spring
into action even if antibodies decline below that level.
To explore this question, Italian researchers followed 571 teenagers 10 and 17 years after they were vaccinated as infants.
When tested in 2003, 10 years
after vaccination, 199 children (group A) had antibody levels below 10
IU/ml and 372 teens (group B) had antibody levels exceeding 10 IU/ml.
Everyone in group A received a vaccine booster.
Seven years later in 2010, the
teens were tested again and researchers found that 67.3% of group A who
received boosters had adequate antibodies compared to 75.8% of group
B, who did not require boosters.
The researchers, writing in the February issue of the journal of Clinical Microbiology and Infection,
reported that the capacity of the teens' immune systems to increase
surface antibodies shows that their immune systems "remembered" the
virus for hepatitis B and continued to confer protection even when the
number of antibodies declined.
Labels: boosters, declining antibodies
