Influenza vaccines: from surveillance through production to protection

Abstract

Influenza is an important contributor to population and individual morbidity and mortality. The current influenza pandemic with novel H1N1 has highlighted the need for health care professionals to better understand the processes involved in creating influenza vaccines, both for pandemic as well as for seasonal influenza. This review presents an overview of influenza-related topics to help meet this need and includes a discussion of the burden of disease, virology, epidemiology, viral surveillance, and vaccine strain selection. We then present an overview of influenza vaccine-related topics, including vaccine production, vaccine efficacy and effectiveness, influenza vaccine misperceptions, and populations that are recommended to receive vaccination. English-language articles in PubMed published between January 1, 1970, and October 7, 2009, were searched using key words human influenza, influenza vaccines, influenza A, and influenza B.

FIGURE 1.

Structure of the influenza virus. The 8 gene segments are contained within a viral envelope with hemagglutinin (HA) and neuraminidase (NA) forming most of the antigenic determinants. The portion of the matrix 2 (M2) protein that is outside the viral envelope is antigenic. PA = polymerase acidic; PB = polymerase basic. From Science, with permission.

FIGURE 2.

How novel influenza strains are introduced into humans. HA = hemagglutinin; NA = neuraminidase. From National Institute of Allergy and Infectious Diseases (NIAID) Web site.

FIGURE 3.

Northern hemisphere influenza vaccine production time-line. Global viral surveillance occurs year-round, which informs the selection of the vaccine strains that occurs between January and March of each year. Vaccine production begins in January and continues through July. Purification and testing start in June and continue through October. Single-dose syringes and multidose vial lots are filled and packaged between July and December and are distributed between August and December for vaccination between late September and the end of the influenza season (often in spring).