Nonetheless, response is sufficient for conferring protection in most elderly persons. However, the need for revaccination is different for some vaccines in the elderly because of waning response. Vaccines consist of whole killed bacterial cells, wholly or partially purified bacterial proteins or polysaccharides, inactivated viruses or purified viral proteins, or live attenuated viruses. Recombinant technology is increasingly used to produce specific bacterial or viral antigens for use in vaccines. Toxoids consist of bacterial toxins that have been modified to be nontoxic, although they retain the ability to induce production of antitoxin antibodies.
Passive immunization is used when exposure to a disease has recently occurred or is anticipated.
All human plasma entering a donor pool is screened for antibody to the bloodborne viral pathogens HIV, hepatitis B virus, and hepatitis C virus. Furthermore, the purification process used to prepare immune globulins excludes such viruses. Adverse Effects Adverse effects do not appear to be different in the elderly than in younger persons. The main type of adverse effect is a hypersensitivity reaction, which occurs because vaccines and toxoids contain specific immunogenic substances. Hypersensitivity to an agent used in culture media is possible but infrequent.