Immunogenicity Trial of Recombinant Influenza Vaccine Among HCP in Israel

This is a randomized, open-label study design. Starting in July 2019, approximately 550 to 700 HCP from two hospitals (275-350 per hospital site) in Israel will be enrolled. Following completion of a written consent form, participants will complete an enrollment survey and grant permission for review of information collected during the SHIRI study, including vaccination status and immune response during the SHIRI study years. Participants will complete an enrollment survey and grant permission to include and integrate information collected during the SHIRI study into the current study's data, including health history, influenza vaccination history, and immune response to vaccination during the SHIRI study years. HCP will be randomly assigned 1:1 to receive a single dose of IIV4 licensed in Israel (expected to be Vaxigrip® Quadrivalent, 15µg of HA per strain) or RIV4 (Flublok® Quadrivalent by Sanofi Pasteur, 45µg of HA per strain) during August-October of 2019. Adverse events following vaccination will be monitored and documented. Blood specimens will be collected prior to vaccination and approximately 28 days after to evaluate immune responses to vaccination.

Eligible HCP who were already vaccinated with Vaxigrip, the vaccine that is routinely available in Israel, at the time they are approached to join the study, will be invited to join the study as part of the Vaxigrip arm. Like randomized participants, participants who were vaccinated with Vaxigrip outside the study will complete a written consent form, an enrollment survey and grant permission for review of information collected during the SHIRI study, including vaccination status and immune response during the SHIRI study years. As part of the consent form, participants will record the estimated date that they received the vaccine, and the location, and will authorize study staff to verify the date of current-year Vaxigrip vaccination in the Clalit EMR and with the hospital vaccination staff. Participants will complete an enrollment survey and grant permission to include and integrate information collected during the SHIRI study into the current study's data, including health history, influenza vaccination history, and immune response to vaccination during the SHIRI study years. Blood specimens will be collected approximately 28 days after to evaluate immune responses to vaccination.