MedImmune to Buy Aviron in Stock Swap

MedImmune Inc. agreed to buy vaccine maker Aviron in a bid to add FluMist, Aviron’s promising treatment for influenza, to its own portfolio of drugs for infectious diseases.

Gaithersburg, Md.-based MedImmune will exchange 1.075 of its shares for each Aviron share. Based on MedImmune’s closing stock price of $38.83, the offer values Aviron at $41.74 a share, or about $1.3 billion.

The transaction is one of the largest ever between two biotechnology companies.

MedImmune shares fell $5.27, or 11.95%, to close at $38.83 on Nasdaq, after the company said the acquisition will hurt earnings in 2002.

Aviron shares rose $4.37, or 12%, to $41.42 on Nasdaq, buoyed by MedImmune’s statement that it expects FluMist to rake in more than $1 billion in annual sales in the United States alone.

The nasal spray still has to be approved by regulators.