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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, 2021.


Vaccination recommendations are made by the Advisory Committee on Immunization Practices (ACIP) of the US Centers for Disease Control and Prevention (Table 30–7). Characteristics of selected COVID-19 vaccines, as of March 2021, are presented in Table 30–8.

Table 30–8.Selected COVID-19 vaccines and adverse effects.1


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 ...

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