Vaccinations for HIV-Infected Inmates
Inmates in this country represent a large reservoir of individuals at risk for vaccine-preventable diseases. Vaccinations are one of the most cost-effective interventions available, with the potential for decreasing morbidity and mortality by preventing or modifying life-threatening disease. According to a recent report to congress1, 11.5 million Americans were released from jails and prisons in 1998. Therefore, immunization efforts targeting inmates have the potential to dramatically impact the health of the incarcerated, those who work with them, and the overall public health of this nation.
Not all vaccines are safe for use in immunocompromised individuals. As a rule, immunocompromised people should not receive vaccines based on live-attenuated organisms. Because of the disproportionately high prevalence of HIV in jails and prisons, the use of live attenuated vaccines must be carefully considered, as some individuals may not be aware of their own advanced HIV infection. On the other hand, the widespread use of highly active antiretroviral therapy (HAART) has resulted in immune reconstitution for many HIV-infected inmates. This may augment the response to vaccination in these patients. This article will review the principles, efficacy, safety and recommendations for immunizations in HIV-infected individuals.
How Vaccines Work
The purpose of vaccination is to prevent disease in the susceptible host. This is done by stimulating the host's immune system to recognize the antigens on microorganisms and produce antibodies or T cell responses capable of fighting off the microorganisms (immunization).
Vaccines can be classified as live attenuated vaccines or inactivated vaccines (see Table 1). Live attenuated vaccines contain microorganisms that replicate and stimulate the host's immune system but are weakened (attenuated) so they are generally unable to produce disease in the immunocompetent individual. In contrast, inactivated vaccines either contain organisms killed by heat or chemicals, or "subunits" of these organisms such as proteins from the cell wall. With inactivated vaccines, there is no riskof acquiring vaccination-related disease. Recombinant vaccines are a form of inactivated vaccine derived from genetically engineered proteins. These vaccines do not contain any microorganisms or their products. Although they are not technically vaccines, toxoids are modified bacterial toxins incapable of producing disease, but able to stimulate the immune system to prevent the disease caused by the bacteria.
Vaccination can stimulate CD4 lymphocytes to become activated. Once in the activated state, CD4 lymphocytes are more at risk to become infected by HIV. Thus, vaccination can theoretically cause more cells to become infected by HIV. In the beginning of the AIDS epidemic, there were concerns that vaccination might accelerate the progression of HIV. Some early studies demonstrated that after receipt of the influenza vaccine or tetanus toxoid, there was a transient increase seen in the HIV viral load of vaccinated individuals.2 However, an abstract presented at this year's IDSA meeting found that among patients on HAART with undetectable HIV viral loads who received the influenza vaccination, there was no increase in HIV viral load.3 Thus, in the era of HAART, sustained viral suppression resulting from effective treatment may diminish the likelihood of post-vaccination viral rebound.
Because HIV-infected persons have altered immune systems, there are special safety concerns when considering vaccination. Live attenuated vaccines can be problematic due to the potential for prolonged viral replication in immunocompromised individuals. In 1992, an AIDS patient developed measles pneumonitis from the measles vaccine.4 In a separate case, a military recruit with asymptomatic HIV infection developed disseminated vaccinia from the smallpox vaccine.
There are also concerns about the efficacy of vaccinations in HIV-infected individuals. Because the immune system can affect the response to vaccines, there may be a lack of or reduced response in HIV-infected individuals. A recent study suggests that viral load suppression is a predictor of response to vaccinations, regardless of the CD4 count. In this retrospective study, 41 HIV-infected patients received three doses of the hepatitis B vaccine and had follow-up hepatitis B serologies performed. Fifty to 60 percent of those patients who had HIV viral loads <400 copies/mL showed an antibody response, regardless of their CD4 counts. In those patients with CD4 counts above 200 and HIV viral loads >400 copies/mL, only 24% showed a serological response. The worst outcomes occurred in patients with CD4 counts <200 and HIV RNA >400 copies/mL, where no patients showed a response.5 Although this study involved a small number of patients and the data are preliminary, it certainly raises concerns about the efficacy of and ideal time to offer vaccinations to patients with advanced immunodeficiency and those with HIV viral loads >400.
When to Vaccinate
Many experts recommend vaccinating HIV-infected individuals early in the course of HIV disease because of concerns that declining immune status will reduce the response to vaccination.6 Although the CD4 lymphocyte count is a surrogate marker for immune status, the minimal CD4 lymphocyte count needed to evoke an immune response is unknown. At low CD4 T-cell counts, HIV-infected adults may not respond to the initial vaccine series and may need additional (booster) doses of vaccine. If patients are to be placed on HAART, some experts recommend delaying vaccination for a few months after the initiation of therapy since immune reconstitution from HAART may result in a better antibody response.
Which Vaccines May Be Used
HIV-infected individuals are at a significantly increased risk for both pneumococcal disease and pneumococcal bacteremia. Many observational studies in the U.S. have demonstrated a decrease in morbidity and mortality among HIV-infected patients who receive the vaccine.6 The pneumococcal vaccine is safe to give to the HIV-infected person because it does not contain live organisms (bacterial polysaccharide vaccine). Therefore, the CDC recommends vaccinating all HIV-infected individuals with CD4 lymphocyte counts >200. The CDC recommends considering vaccinating HIV-infected individuals with CD4 lymphocytes <200 although clinical evidence is lacking. The ACP and AAP recommend revaccination with a single dose for children >2 years and adults who are at highest risk for serious pneumococcal infection and for individuals likely to have a rapid decline in antibody levels, provided five years have elapsed since the first dose. Revaccination every five years may be prudent in HIV-infected populations. Although this vaccine is safe, the efficacy in advanced HIV-infected patients may be reduced. In cases where the first vaccination was given when the CD4 lymphocyte count was <200, revaccination can be considered if the CD4 count is >200 as a result of HAART, as recommended by the USPHS and IDSA.
Influenza vaccine is derived from killed virus. The vaccine is updated every year based on circulating flu strains. It is safe for administration to patients who have HIV and should be given annually to those who are HIV-infected. The only contraindication to influenza vaccination is a history of an anaphylactic hypersensitivity to eggs or previous vaccination. This vaccination should preferably be administered every year before influenza season begins (October through November) but there is still a potential benefit to those who receive this vaccination later in the influenza season (until March).7, 8
Hepatitis A and Hepatitis B Vaccines
Both the hepatitis A and B vaccines are safe in HIV-infected individuals. Hepatitis A vaccination is recommended for men who have sex with men, injection drug users, and persons with chronic liver disease including hepatitis C.7
The CDC recommends vaccinating all patients who are infected with hepatitis C against hepatitis A and B because of the increased risk of fulminant hepatitis in these patients. In some correctional institutions where there is a high prevalence of hepatitis C, it may be cost-effective to vaccinate all HIV-infected inmates for hepatitis A.
Hepatitis B vaccination is recommended for all sexually active adults and individuals in long-term correctional facilities. Hepatitis B vaccination is neither recommended nor has been shown to be effective in HbsAg positive individuals. Because of the high prevalence of past hepatitis B infection among inmates, it may be cost-effective to screen for hepatitis B prior to routine vaccination. Levels of hepatitis B surface antibody >10 IU/ml are considered protective against hepatitis B. People who do not respond should be revaccinated with an additional one to three doses.8
The CDC has recommended an alternative accelerated hepatitis B dosing schedule for adults. After the first dose, the second dose should be administered one to two months later, and the third dose can be administered as early as four months after the first.9
Tetanus Diphtheria (Td) Vaccine
The tetanus diphtheria (Td) vaccine is an inactivated toxoid and is, therefore, safe to give to immunocompromised patients. Even though many inmates will have been vaccinated as children, they should receive booster doses every 10 years.
Varicella-Zoster Virus (VZV) Vaccine
Because of the concern for acquiring live viral infections and transmission of vaccine-derived varicella to susceptible populations, varicella-zoster virus vaccine is generally not recommended in HIV-infected adults regardless of their immune status. HIV-infected patients who have not had chickenpox should also avoid contact with and exposure to varicella (chickenpox) or zoster (shingles).10 Recommendations for treating HIV-infected patients who are exposed to VZV are the same as for pregnant women (another group of patients at risk). Within 96 hours of an exposure to a patient with varicella or zoster, HIV-infected adults may receive a prophylactic dose of varicella-zoster immune globulin (VZIG). There are no data supporting the use of antivirals such as acyclovir in this population to prevent varicella or zoster.
Measles, Mumps, and Rubella (MMR) Vaccine
Most HIV-infected individuals will have received MMR as children, and revaccination is therefore not routine. The CDC recommends MMR vaccine be given to HIV-infected persons who have not previously been vaccinated, who are not severely immunocompromised (CD4 counts >200). Because of the low prevalence of these diseases in the U.S. and the potential for decreased efficacy and disseminated disease, the risks of the vaccine may outweigh the benefits. Severely immunosuppressed patients exposed to measles should receive immune globulin (IG) prophylaxis regardless of their vaccination status.
Two types of polio vaccine are available. The oral polio vaccine is a live virus vaccine. Because of the risk of polio virus replication in immunocompromised patients, it should not be administered to HIV-infected persons, their household contacts, or nursing personnel who are in close contact with HIV-infected patients. The inactivated polio vaccine (IPV) is a suitable alternative for non-immune immunocompromised persons.
HIV-Infected Pregnant Woman
When vaccinating HIV-infected pregnant women, the potential risk to the fetus and to the mother must be considered. In general, inactivated vaccines (influenza), bacterial vaccines (pneumococcal vaccine), and toxoids (Td) are safe in pregnancy.
Pregnant women in their second and third trimesters are at increased risk for serious complications from influenza and should be vaccinated before flu season. Hepatitis B vaccine is recommended for pregnant women who are at risk for hepatitis B infection.
Pneumococcal vaccination is safe and is recommended in pregnancy for HIV-positive patients who have not been vaccinated in the past 5 years. In general live virus vaccines are not recommended for HIV-infected pregnant women because of the risk for congenital varicella or rubella and the risk of disseminated disease in the mother.7
HIV-infected individuals in correctional institutions can benefit from receiving vaccines to prevent pneumococcal disease, flu, diphtheria and tetanus, and hepatitis A and B. The immune status of the HIV-infected individuals may influence both the safety and efficacy of the vaccine. HIV-infected patients should generally avoid live-virus or live-bacterial vaccines. Inactivated vaccines are safe and should be offered to those who are at risk for disease. Patients with non-suppressed HIV viral loads and those with advanced disease may not respond or may have a blunted response to vaccination. In general, vaccines should be avoided during pregnancy, if possible. If vaccination must take place during pregnancy, only inactivated vaccines should be used. Further research is needed to evaluate the efficacy and the safety of vaccines in HIV-infected patients effectively treated with HAART.
Becky L. Stevenson is Assistant Professor of Medicine, Univ. of North Carolina, Chapel Hill, Co-director of HIV Services, North Carolina Department of Corrections, Raleigh, NC.
Back to the HEPP Report December 2002 contents page.
This article was provided by Brown Medical School. It is a part of the publication HEPP Report.