Response to Hepatitis B Vaccine in HIV Positive Patients

Introduction

Preventing HIV patients from acquiring Hepatitis B infection is a critical and timely public health concern. HIV patients have a much higher rate of acute hepatitis B (12.2. cases per 1,000 person-years) compared with the general population.  Furthermore, they have a higher rate of becoming chronically infected, and a lower rate of clearing hepatitis B e antigen. In addition to education directed toward decreasing high risk behavior, vaccination is the best tool in protecting these HIV patients. Prior studies, however, suggest that the vaccine has a low response rate in immunodeficient patients. Therefore the aim of this study was to determine the immune response to the standard hepatitis B vaccine in HIV positive patients in an urban outpatient clinic in the Bronx that serves primarily Medicare or Medicaid patients.

Method

A retrospective chart review of all patients who attended the HIV clinic was completed in 2006.  Information regarding hepatitis B vaccines, hepatitis B serologies and patient demographic characteristics were collected and analyzed using SPSS.  This study was approved by the SBH IRB.

Results

Nine hundred and twenty four charts were reviewed. Results of subjects’ hepatitis B serology are illustrated in figure 1.

Three hundred and four (33%) patients had negative hepatitis B serologies and were therefore eligible for vaccination.  Two hundred and twenty five (74%) subjects received at least one hepatitis B vaccination.

To determine if the members of the study group had an immune response to the standard hepatitis B vaccine series,  these subjects needed to have received at least 3 vaccinations (304 subjects) and have post vaccine serologies completed within one year of vaccination (61 subjects).  Of note, there is no recommendation to obtain post vaccine serologies. In our patients clinicians might have obtained these serologies for various reasons including: determining if the vaccine elicited an immune response, abnormal liver function tests, or duplicate ordering.

The average age of these 61 subjects is 41years; 39% were males, 98% were Hispanic or Black. Only 19 subjects (31%) developed antibodies to hepatitis B (figure 2).

Three subjects received 6 or more vaccinations. One of these subjects developed antibodies. Study subject’s co-morbidities are listed below:

Although not statistically significant there was a trend for developing a vaccine response in subjects who had a CD4 count above 200, or a viral load below 100,000. Of the 10 subjects with CD4 counts above 500, 50% developed a vaccine response.

Discussion

This study was performed in a large urban clinic in the Bronx, New York. Study subjects were primarily Hispanic or Black. The mode of HIV acquisition was through drugs or sex. At baseline, two thirds of our subjects were hepatitis B surface antibody or core antibody positive. Only 0.4% were hepatitis B surface antigen positive. The remaining third had negative serologies for hepatitis B and are routinely offered hepatitis B vaccination. Seventy four percent of eligible subjects received at least one vaccine.

The response to the hepatitis B vaccine in our HIV subjects was very poor: only 31% developed hepatitis B surface antibodies. Five previous studies ^{5 6 7 8}  have examined vaccine response in HIV positive patients. The response rate varied between 17.5% and 59%. Our study population had advanced HIV disease (average CD4 329, 36% had CD4 &ln;200; 79% were on HAART, and only 31% had viral loads &ln; 400). It is possible that the vaccine’s efficiency might be superior in a subpopulation of patients with less advanced HIV disease. Indeed, the rate in one study ¹ was as high as 87% in patients with CD4 counts above 500.  In our small number of subjects with CD4 above 500, 50% developed a vaccine response.

Most of our patients were Black or Hispanic. It is unclear if ethnicity is an important factor in Hepatitis B vaccine response. One study ⁴ in HIV patients, describes a response rate of 27% in African Americans compared to 76% in Whites.

This study highlights the need to assess antibody status in HIV positive patients after receiving the Hepatitis B vaccine in order to determine if they should receive a second series of hepatitis B vaccines. In the future, a larger number of treatment options including 1) more immunogenic vaccine, 2)increasing the hepatitis B vaccine dose, and 3) administering the vaccine early during an HIV infection, should be available to protect these HIV positive patients who are at high risk for acquiring Hepatitis B.