Although influenza is usually a self-limited disease with rare sequelae, it can be associated with severe morbidity and mortality in older persons or those with chronic diseases. Influenza vaccines produce long-lasting immunity. However, antigenic shifts, primarily in type A rather than type B influenza virus, require yearly reformulation of the vaccine to contain the antigens of strains considered most likely to cause disease. Protection is correlated with the development of antihemagglutinin and antineuraminidase antibodies, which decrease the patient’s susceptibility and the severity of the disease. The influenza vaccine is as effective in HIV-seropositive patients as it is in HIV-seronegative patients, regardless of the individual’s CD4+ T-cell counts. In the United States, annual vaccination is recommended for all adults and for children older than 6 months. The influenza vaccine is well tolerated, and there has been no increased risk of neurologic complications with the vaccines administered after 1991. Trivalent and quadrivalent inactivated influenza vaccines (IIVs) are available, as well as a recombinant influenza vaccine. A live-attenuated influenza vaccine (LAIV) is also available but may not be as effective as the IIV. Pregnant women may safely receive the IIV. Health care workers working with severely immunocompromised patients should receive the IIV. The IIV and LAIV should not be administered to persons with anaphylactic hypersensitivity to eggs, but the recombinant vaccine (Flublok) may be used. A high-dose vaccine for patients older than 65 years is also available. Antiviral agents may be indicated to treat influenza in high-risk patients who are more likely to have serious sequelae from influenza (eg, elderly individuals, pregnant women, individuals with certain chronic conditions). The CDC (and others) suggest treatment with neuraminidase inhibitors (zanamivir, oseltamivir, peramivir) due to emerging resistance to amantadine and rimantadine.
Grohskopf LA, Sokolow LZ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices—United States, 2017–18 influenza season. MMWR Recomm Rep. 2017;66(2):1–20.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.