Seasonal influenza is a contagious respiratory illness that may be prevented by annual influenza vaccination. In Ireland, those aged 65 years and older are eligible to receive a free annual influenza vaccine through the Health Service Executive (HSE) Seasonal Influenza Vaccination Programme. Currently, a standard influenza vaccine is used. Vaccine effectiveness may be reduced in some individuals due to an ageing or compromised immune system. Therefore, enhanced influenza vaccines have been developed in an attempt to increase vaccine effectiveness. The Department of Health requested that HIQA complete a health technology assessment (HTA) of using an enhanced inactivated influenza vaccine for those aged 65 years and older in the Seasonal Influenza Vaccination Programme. The protocol document outlines the evidence synthesis approach that HIQA’s evaluation team will use to complete this piece of work.