HIV infection, because of the immunocompromised state, is a risk factor for morbidity and mortality caused by a number of infections that can usually be prevented by immunization. A number of factors contribute to the HIV-infected patient's "net state of immunosuppression" including defects in cell-mediated immunity, B cell dysfunction, and suboptimal humoral immune responses . In the absence of effective therapy, the immunocompromise is continually progressive. On the other hand, patients who respond to highly active antiretroviral therapy (HAART) have substantial increases in their CD4 lymphocytes, suggesting improved immunity.
In 2009, the United States Centers for Disease Control and Prevention, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America reconvened to update their previous joint guidelines to include information relevant to HAART . These recommendations continue to focus on prevention of infection, including immunization, starting at the time of diagnosis (figure 1). Although vaccine efficacy is usually compromised in advanced disease, adequate responses can be achieved when vaccines are administered early after HIV infection . Concerns have been raised about vaccine safety, specifically the risk of activating the immune system and the potential for increasing HIV replication and promoting HIV infection. As discussed below, the benefits of administering vaccines appear to outweigh the risks.
Issues related to postexposure prophylaxis are discussed separately. (See "Management of healthcare personnel exposed to HIV".)
Inactivated vaccines are generally acceptable and live vaccines are generally avoided in persons with HIV infection . However, some live vaccines (eg, varicella) are recommended in HIV-infected patients with CD4 cell counts >200 cells/microL. The specific recommendations for each vaccine are discussed below.
Tetanus toxoid, diphtheria toxoid, and acellular pertussis vaccines — HIV-infected patients have similar immunity to tetanus as an age-matched normal population, but diphtheria immunity is lower than expected . Since the immune responses to tetanus and diphtheria are T cell-dependent, the response to immunization is lower in patients with advanced HIV disease [6,7]. One study noted a transient increase in plasma HIV-1 RNA levels after immunization with tetanus toxoid, but there were no long-term consequences of this upregulation .