Influenza vaccination has become the standard of care for several population groups. The Centers for Disease Control and Prevention (CDC) and the Canadian National Advisory Committee on Immunization (NACI) currently recommends this vaccine for children > 6 months, healthy adults, the elderly and all immunocompromised patients such as those with organ transplants (www.cdc.gov). The currently available influenza vaccine is a subunit vaccine containing the purified surface glycoproteins of the virus, hemagglutinin and neuraminidase. The vaccine contains 15g antigen from each of 2 circulating subtypes of influenza A and 15 g of an influenza B subtype (www.who.int). The vaccine is administered by the intramuscular route, generally in the deltoid muscle in adults. The standard dose is 0.5 mL.