CPT® Code 90656

A trivalent, split virus, preservative-free influenza vaccine (IIV3) is designed for intramuscular administration. This vaccine differs from immune globulins, which provide short-term, passive immunity; instead, it offers active, long-term immunity. The mechanism of action involves exposing the recipient's immune system to altered versions of specific influenza viruses, prompting the immune system to produce its own antibodies. This process enables the body to "remember" how to generate antibodies upon subsequent exposure to the same antigens. The formulation is specifically preservative-free, meaning it does not contain the preservative thimerosal or contains only trace amounts, thus classified as either thimerosal-free or thimerosal-reduced. The U.S. Food and Drug Administration (FDA) recognizes both formulations as preservative-free. The vaccine is administered via intramuscular injection, which is a separate procedure that should be reported independently. The production of the influenza vaccine involves the use of embryonated chicken eggs, where the virus is harvested, inactivated with formaldehyde, concentrated, purified, and chemically disrupted to create a split virus. This trivalent vaccine is formulated to protect against three specific influenza viruses, including two distinct strains of influenza type A and one strain of influenza type B. For coding purposes, the CPT® code 90656 is designated for the 0.5 mL dosage of this vaccine, while code 90655 is used for a 0.25 mL dosage, with both codes solely reporting the vaccine product used.