Response to Hepatitis A (HAV) vaccine determined by CD4 count
Simon Collins, HIV i-Base
Rimland and colleagues from the VA Medical Center, Atlanta, Georgia analysed responses to hepatitis A vaccine in 214 patients who were vaccinated between 1996 and 2003 (standard dose and schedule).
Overall, 130 of 214 vaccinated individuals developed HAV antibody (61%). Response rate by CD4 count at time of vaccination were 83%, 62%, 39%, 27% and 8% in patients with CD4 >500, 201-500, 101-200, 51-100 and <50 cells/mm3 respectively (p<0.0001).
In a multivariate analysis, only CD4 at time of vaccination (and not CD4 nadir) was associated with absence of response (p<0.0001). HCV infection was not associated with response.
The study concluded that determination of hepatitis A antibody after vaccination should be considered in all HIV patients receiving HAV vaccine. CD4 at time of vaccination is the critical determinant of response to HAV vaccine. Also, that the absence of a multivariate association with nadir CD4 suggested that patients may respond to HAV vaccine after immunologic reconstitution in response to HAART.
Response to HA vaccine by CD4 count at time of vaccination:
|CD4 count (cells/mm3)||Response rate|
These two sets of studies underpin the importance of early consideration of Hepatitis A and B vaccination in HIV positive patients and in particular patients co-infected with HCV.
Overall, CD4 counts at time of vaccination, rather than nadir CD4 counts, seem to be an important factor in determining response to hepatitis A (as judged by appearance of antibodies in HAV). Therefore, early use of vaccination is optimum, but as demonstrated by Rimland et al, there is a 60% or more response for HAV vaccine with CD4 counts over 200 cells/mm3.
The use of double-dose vaccination in hepatitis B is a strategy already adapted by renal physicians for patients on dialysis, and Fonseca and colleagues provide evidence that this may be applicable in HIV-infected patients as well.
Rimland D, Guest JL. Response to hepatitis A vaccine in HIV patients in the HAART era. XV Intl AIDS Conference, Bangkok. Abstract MoPeB3299 (this report based on revised abstract in poster).