1. Influenza Vaccines: From Surveillance Through Production to Protection
Pritish K. Tosh, MD, Robert M. Jacobson, MD, Gregory A. Poland, MD 
Mayo Clinic Proceedings 
Volume 85, Issue 3, Pages (March 2010)
DOI: /mcp
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2. 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,23 with permission.
Mayo Clinic Proceedings  , DOI: ( /mcp )
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3. 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.63
Mayo Clinic Proceedings  , DOI: ( /mcp )
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4. 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).
Mayo Clinic Proceedings  , DOI: ( /mcp )
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