MedImmune to Buy Aviron for $1.5 Billion

MedImmune

(MEDI)

agreed to acquire

Aviron

(AVIR)

for stock worth $47.41 a share, or $1.5 billion.

Aviron, based in Mountain View, Calif., owns an experimental flu-prevention treatment called FluMist that Medimmune, based in Gaithersburg, Md., hopes to launch next year.

In the premarket Instinet session, Aviron was up $4.45, or 12%, to $41.50, while Medimmune was down $4.10, or 9%, to $40.