Screening for hepatitis B virus (HBV) infection is a critical part of HIV care because both HIV and HBV share the same risk factors of transmission. The interpretation of hepatitis B serology in an HIV-infected patient is well defined. We report the first case of an HIV-infected patient with a positive hepatitis B surface antigen, negative core antibody, and a negative HBV DNA following HBV vaccination.
A 34-year-old Latino man was diagnosed on 1 February 2008 with HIV disease, which he acquired through MSM after previously testing negative. His past medical history was remarkable for childhood epilepsy, a functional heart murmur, syphilis, seasonal allergies, anal condyloma, tobaccoism, depressive disorder, and insomnia. He denied substance use. He had a full hepatitis A/B/C screening as part of his initial assessment and all his serologies came back negative. Hepatitis A and B vaccines were administered. Shortly thereafter, he was screened and subsequently enrolled in a phase 3 clinical trial targeting antiretroviral naive HIV-1-positive individuals and was randomized in a placebo-controlled manner to receiving Stribild versus Atripla. His screening laboratories revealed a positive hepatitis B surface antigen (HBsAg) and that was confirmed by the laboratory. Full laboratory data can be seen in Table 1. The patient was completely asymptomatic and he denied any right upper quadrant pain, rash, dark urine, loss of appetite, fever, or arthralgias. His physical examination was unremarkable for jaundice, scleral icterus, abdominal pain, and rash. Subsequent laboratory testing failed to reveal the presence of hepatitis B core antibody (Anti-HBc), nor did he mount any signs of active hepatitis. Additionally, his HBsAg became undetectable at retesting approximately 1 year after his initial positive test.
Isolated transient hepatitis B surface antigenemia following hepatitis B vaccination is not uncommon. Numerous studies have shown a false-positive HBV surface antigenemia in between 17% and 65% of neonates, which was seen between 33 h and 8 days after vaccination. This effect lasted for up to 21 days in these studies [1–3]. In a study conducted by Otag , three false-positive HBsAgs were seen in 44 patients studied (7%) after one vaccination with three different hepatitis B vaccines: Engerix B, Hepavax Gene, and Gen Hevac B. All of these participants were positive at 24 h and negative at 3 days. Other studies have shown results as high as 47% in adults . Of note, all of these studies were conducted in HIV-negative individuals. After a thorough chart review, it was noted that the patient received a Twinrix vaccine 2 days prior to obtaining the HBsAg positivity.
This transient HBsAg occurred after a dose of Twinrix, which contains half of the standard dose of a HBsAg in a conventional HBV vaccine. As far as we know, this is the first case report of HBV surface antigenemia captured following Recombivax, which is the HBV vaccine component of the Twinrix. This antigenemia was depicted 48 h after vaccination. Antiretroviral therapy initiation with a TDF/FTC-based regimen, the treatment of choice of HBV, rendered the follow-up and usage of the HBsAg and HBV DNA, as markers of acute hepatitis B infection, unreliable. The fact that the patient never mounted an anti-HBc response ruled out a previous exposure to HBV. Hence, the only plausible explanation accounting for his positive HBV surface antigenemia would have been the passive detection of HBV surface Ag administered during vaccination. The explanation for detecting a positive surface Ag in our patient is the fact that the assay used will depict HBsAg irrespective of whether it is derived from an acute viral infection or passively transmitted following vaccination. The clearance period of passive transmission of antigenemia can last up to a few weeks .
In summary, the detection of an isolated positive HBsAg does not always imply an acute HBV infection and should prompt clinicians to investigate the timing of the blood test in regard to a recent HBV vaccination, before initiating HBV infection work-up. This will minimize both the psychological burden on the patient and healthcare cost.
Conflicts of interest
There are no conflicts of interest.
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