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                                                                    EXHIBIT 23.1


               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

     We consent to the reference to our firm under the caption "Experts" in the
Registration Statement (Form S-3) and related Prospectus of Aviron for the
registration of 450,000 shares of its common stock and to the incorporation by
reference therein of our report dated January 25, 2001, with respect to the
consolidated financial statements of Aviron included in its Annual Report (Form
10-K) for the year ended December 31, 2000 filed with the Securities and
Exchange Commission.

                                                           /s/ Ernst & Young LLP

Palo Alto, California
April 4, 2001