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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 Amendment
No. 1 to the Registration Statement (Form S-3) and related prospectus of Aviron
for the registration of 200,000 shares of its common stock and to the
incorporation by reference therein of our report dated February 17, 2000, with
respect to the financial statements of Aviron included in its Annual Report
(Form 10-K/A) for the year ended December 31, 1999, filed with the Securities
and Exchange Commission.

                                                           /s/ Ernst & Young LLP

Palo Alto, California
January 8, 2001