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 HIV and Hepatitis.com Coverage of the
49
th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2009)
September 12-15, 2009, San Francisco, CA
 The material posted on HIV and Hepatitis.com about the 49th ICAAC is not approved by the American Society for Microbiology
High-dose Hepatitis B Vaccination May Protect HIV Positive People Who Do Not Respond to a Standard Dose

Revaccination with a higher vaccine dose may offer protection against hepatitis B virus (HBV) infection for people with HIV who do not achieve an adequate antibody response after previous standard-dose vaccination, according to a poster presented at the 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2009) last month in San Francisco.

By Liz Highleyman

HIV and HBV have overlapping transmission routes, and treatment guidelines recommend that HIV positive people should be tested for and, if susceptible (i.e., have no evidence of prior exposure to the virus), vaccinated against hepatitis B, which is more likely to persist and cause serious liver damage in this population.

However, prior research has shown that HIV positive people -- especially those with advanced immune suppression -- may respond poorly to hepatitis B vaccination, leading scientists to explore new strategies. Studies have shown HIV positive response rates ranging from about 20% to about 50%, compared with 90% or higher among HIV negative people.

In this study, researchers from the University of Michigan Health System performed a retrospective chart review of adult HIV patients at a single center who were vaccinated with either the standard 20 mcg Energix-B vaccine or the Twinrix combination hepatitis A and B vaccine. A subset of non-responders received a higher-dose 40 mcg Energix-B vaccine series.

Most participants (75%) were men, the average age was about 40 years, 67% were white, and 66% were on combination antiretroviral therapy (ART). The average CD4 count at the time of the first vaccine dose was approximately 425 cells/mm3 and the nadir (lowest-ever) count was about 300 cells/mm3.

The investigators analyzed factors associated with success or failure to mount an adequate antibody response, or HBV seroconversion (defined as anti-HBs titer > 10 mIU/mL).

Results

Among 215 adults who received standard-dose vaccination, the response rate was 46.5%.
Among 100 patients who did not respond, 30 received high-dose revaccination.
Among the 30 revaccinated individuals, the response rate was 66.7%.
Factors associated with response to standard-dose vaccination were:
 
- Younger age (37.6 vs 40.6 years; odds ratio [OR] 0.97 per year; P = 0.03);
- High CD4 cell count at the time of the first vaccine dose (496 vs 384 cells/mm3; OR 0.13 per 100 cells/mm3; P = 0.02);
- Receiving Twinrix rather than standard-dose Energix as the initial vaccine (54% vs 39%; OR 2.3; P = 0.003).
Higher CD4 count was also associated with good response to high-dose revaccination (563 vs 306 cells/mm3; OR 2.0 per 100 cells/mm3; P 0.02).
All these factors remained significant independent predictors of response in a multivariate analysis.
Patient sex, use of ART, and HIV viral load did not have a significant association with vaccine response.

"High dose revaccination appears to be a viable strategy to achieve seroconversion among HIV-infected patients that have not responded to standard dose vaccination," the investigators concluded. "Higher CD4 [count] at vaccination, younger age, and receipt of Twinrix were independently associated with standard dose vaccination seroconversion."

The higher likelihood of response to Twinrix versus Energix-B, they added, suggests the need for future prospective studies comparing these vaccines in HIV positive people.

University of Michigan Health System, Ann Arbor, MI.

10/02/09

Reference
N Pettit, DD Depestel, PN Malani, and J Riddell. Risk Factors Associated with Non-Response to Standard Dose Hepatitis B Vaccine (SDV) and High Dose Revaccination (HDR) among HIV-Infected Patients. 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2009). San Francisco. September 12-15, 2009. Abstract G1-871.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



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