When vaccinated against hepatitis B virus as adults, health care workers appeared to receive robust and long-lasting vaccine protection, according to researchers from the National Institute of Diabetes and Digestive and Kidney Diseases.
Moreover, rapid and strong response to a booster in this population suggested the vaccine provided a long-term immunologic memory to hepatitis B virus (HBV) surface antigen and that booster vaccination may not be necessary, they said.
The researchers recruited health care workers (HCWs) at the NIH Clinical Center and Suburban Hospital in Bethesda, Md. All eligible participants (n=159) had undergone vaccination with a three-dose series of plasma-derived or recombinant HBV vaccine within a 6-month period. Eligible participants were aged 18 to 60 years at vaccination.
Participants were categorized based on the time elapsed since their initial HBV vaccine dose. The strata were as follows: 10-15 years after vaccination (group 1; n=50); 16-20 years after vaccination (group 2; n=50); and more than 20 years after vaccination (group 3; n=59).
The researchers conducted serological testing of all participants for HBV status. Serum samples were assayed for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc), and anti-HBs concentration. Boosters were offered to participants with anti-HBs less than 12 mIU/mL, and these patients were retested 1, 7 and 21 days later. The researchers also compared pre-and post-vaccination anti-HB levels in a subgroup of 36 patients with available data.
Anti-HBs levels less than 12 mIU/mL were found in 18% of group 1, 26% of group 2 and 24% of group 3. Four participants tested positive for anti-HBc, while none were positive for HBsAg. Logistic regression analysis revealed older age at vaccination was the only predictive factor for insufficient anti-HBs levels (P=.0005). Of 36 participants who were offered boosters due to anti-HBs levels less than 12 mIU/mL, 34 received the booster, and within 3 weeks, 94% of these participants had anti-HBs levels greater than 12 mIU/mL.
Based on these findings, HBV booster vaccines are likely unnecessary for HCWs, according to the researchers.
“Seventy-seven percent of the study group maintained an antibody level that is considered protective or adequate. The rapid and robust response to booster among HCWs with absent or inadequate anti-HBs levels suggests that even these persons would be protected upon HBV re-exposure,” they wrote. “These data support current guidelines that booster vaccination is not necessary in otherwise healthy HCWs.”
Disclosure: The researchers are employees of the US government and report no relevant financial disclosures.