After repeated setbacks in the last mile of the regulatory process for its FluMist intranasal live cold-adapted trivalent influenza vaccine - setting up production - Aviron is taking over primary responsibility for manufacturing the product.

Downstream issues have been at the forefront of delays in FluMist development. In 1998, AVIR received a refusal-to-file letter from the FDA that cited validation issues with respect to operations and performance, instruments at the product