Reactions and antibody response to live influenza vaccine prepared from the Iksha (A2) strain. (A report to the Medical Research Council by their Committee on Influenza and other Respiratory Virus Vaccines)

Two field trials of A 2 live influenza vaccine (Iksha) are described; the clinical reactions and antibody response in three earlier trials are compared. The antibody response in the last two trials was unsatisfactory and was inferior to that observed in the earlier investigations. This reduction in response was probably due to an alteration in the virus during further passage.