November 2007

HIV and Immunizations

Heather Huentelman, PharmD, BCPS, LT USPHS, Clinical HIV Pharmacist
Phoenix Indian Medical Center, HIV Center of Excellence

The Advisory Committee on Immunization Practices (ACIP) has updated the Recommended Adult Immunization Schedule for October 2007-September 2008, the updated guidelines are available online at http://www.cdc.gov/mmwr/pdf/wk/mm5641-Immunization.pdf PDF - 162KB and will be published November 20, 2007 in the Annals of Internal Medicine.

HIV has always been a part of the special populations or disease specific adult recommendations. Previously, there were recommendations to withhold certain vaccines from “severely immunocompromised” HIV patients. However, “severely immunocompromised” was not previously defined in the document by a specific CD4 count. In the updated guidelines, vaccines have been recommended for HIV patients based on their CD4 count. CD4 counts <200 cells/uL would classify the patient as having an AIDS diagnosis. It is great that the recommendation is based on CD4 count and not on AIDS diagnosis. CD4 counts can improve but once a patient has an AIDS diagnosis, they will always have an AIDS diagnosis. A patient may present with a CD4 count of 54 cells/uL but with treatment achieve a new baseline of 300 cells/uL. That person will continue to have an AIDS diagnosis but based on CD4 count would be recommended to receive additional vaccines.

It is safe to give non-live vaccines to HIV patients, this includes Td/Tdap, HPV, Influenza, Pneumococcal, Hepatitis A, Hepatitis B, and meningococcal. Three vaccines (MMR, varicella, and zoster) are contraindicated if a patient has a current CD4+ cell count of < 200 cells/uL, one additional vaccine FluMist ® is contraindicated in “severely immunocompromised” persons.

When a new patient presents to clinic, they should be evaluated for immunity from measles, mumps, rubella, varicella, and Hepatitis A by ordering total antibody tests or IgG antibodies for each of these. Hepatitis B should be assessed by checking the total surface antibody and total core antibody to differentiate between active (had the disease) and passive (vaccinated) immunity. Once their immunity status has been determined, vaccines can be given for anything that the patient is missing.

Pneumococcal vaccine is recommended for 2 doses five years apart. The question is will 2 doses give the person life-time immunity and protection from pneumococcal pneumonia? Many providers continue to give the pneumococcal vaccine every five years regardless of how many doses the patient has had in the past. There is no evidence that additional vaccines will do any harm and not enough evidence to show that 2 doses will protect a young patient for a lifetime.

There is controversy surrounding the effectiveness of immunizations in severely immunocompromised patients. These patients may not be able to mount a response to a vaccine with a lower CD4 count and will not have the expected immunity. For example, a patient presents to your clinic with a CD4 count of 24 cells/uL and is given a Tdap vaccine. The patient would not be due for another vaccine for 10 years, however, many providers would consider giving the Tdap again when the patient has restored immune function. It is much easier with vaccines that can be followed with antibody testing. For a patient given a Hepatitis A 2 dose series, the effectiveness of the vaccine can be proven with antibody screening.

Vaccinations are a critical part of care for the HIV positive population. Indian Health Services continues to be a leader in consistently providing immunizations to patients. Immunization needs should be reviewed on a quarterly basis and an extensive review may be appropriate when the patient receives their annual flu vaccination. Although we do not vaccinate patients for tuberculosis, annual PPD screening can also be evaluated with vaccinations.

Reference:

The Advisory Committee on Immunization Practices (ACIP) Recommendation Adult Immunization Schedule – United States, October 2007- September 2008. MMWR Weekly October 19, 2007, Vol 56, No 41 http://www.cdc.gov/mmwr/pdf/wk/mm5641-Immunization.pdf PDF - 693KB [ACCESSED 10-25-07]

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