has function has role immunizes against disease immunizes recipient influenza Equus caballus licensed horse vaccine USDA licensed vaccine role preventive vaccine function prophylactic vaccine equine influenza vaccine inactivated influenza vaccine equine influenza killed virus vaccine (USDA: 1505.20) VIOLIN: https://violinet.org/vaxquery/vaccine_detail.php?c_vaccine_id=1736 1736 USDA: 1505.20 vaccine Asiyah Yu Lin licensed influenza vaccine USA licensed veterinary vaccine inactivated vaccine role