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Immunization is one of the most important tools (along with sanitation) used to prevent morbidity and mortality from infectious diseases. In general, the administration of most vaccinations induces a durable antibody response (active immunity). In contrast, passive immunization occurs when preformed antibodies are given (eg, immune globulin from pooled serum), resulting in temporary protection which is a less durable response. The two variants of active immunization are live attenuated vaccines (which are believed to result in an immunologic response more like natural infection), and inactivated or killed vaccines.

The schedule of vaccinations varies based on the risk of the disease being prevented by vaccination, whether a vaccine has been given previously, the immune status of the patient (probability of responding to vaccine) and safety of the vaccine (live versus killed product, as well as implications for the fetus in pregnant women). Recommendations for healthy adults as well as special populations based on medical conditions are summarized in Table 30–7, which can be accessed online at

Table 30–7.Recommended adult immunization schedule—United States, 2020.


Vaccination recommendations are made by the Advisory Committee on Immunization Practices (ACIP) of the US Centers for Disease Control and Prevention (Table 30–7).


Given the uncertainty of risks to the fetus, vaccination during pregnancy is generally avoided with the following exceptions: tetanus (transfer of maternal antibodies across the placenta is important to prevent neonatal tetanus), diphtheria, and influenza. Live vaccines are avoided during pregnancy.

Influenza can be a serious infection if acquired in pregnancy, and all pregnant women should be offered influenza (inactivated) vaccination. The live attenuated (intranasal) influenza vaccine is not recommended during pregnancy.


HIV-infected patients have impaired cellular and B cell responses. Inactivated or killed vaccinations can generally be given without any consequence, but the recipient may not be able to mount an adequate antibody response. Live or attenuated vaccines are generally avoided with some exceptions (ie, in patients with CD4+ T lymphocytes greater than 200 cells/mcL). Guidelines for vaccinating HIV-infected patients have been issued jointly by the Centers for Disease Control and Prevention, the US National Institutes of Health, and the HIV Medical Association of the Infectious Diseases Society of America. The following non-live vaccines are recommended for all HIV-infected patients: tetanus and diphtheria toxoid (Tdap as a booster once, followed by Td boosters every 10 years), HPV (in women and men until age 26, and potentially up to age 45), inactivated influenza, the 13-valent pneumococcal conjugate vaccine (PCV13), pneumococcal polysaccharide (PPSV23), hepatitis A (for HIV-infected men who have sex with men, injection drug users, patients with chronic liver disease), hepatitis B, and meningococcal ...

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