8-K

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                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D. C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934

                        Date of Report: September 4, 2001
                Date of earliest event reported: August 31, 2001


                                     AVIRON
             (Exact name of registrant as specified in its charter)

                                    DELAWARE
                 (State or other jurisdiction of incorporation)


           0-20815                                   77-0309686
    (Commission File No.)                (IRS Employer Identification No.)


                             297 N. BERNARDO AVENUE
                         MOUNTAIN VIEW CALIFORNIA 94043
              (Address of principal executive offices and zip code)

       Registrant's telephone number, including area code: (650) 919-6500


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ITEM 5. OTHER EVENTS.

         On September 3, 2001, we issued a press release announcing receipt of a
complete response letter on August 31, 2001 from the U.S. Food and Drug
Administration relating to our Biologics License Application submitted on
October 31, 2000 for licensure of FluMist(TM). A copy of the press release is
attached as an exhibit hereto and incorporated by reference herein in its
entirety.

ITEM 7. EXHIBITS.

Exhibit 99.1   Press Release, dated September 3, 2001, entitled "Aviron Receives
               Complete Response Letter Following FDA Review of FluMist(TM) BLA"


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                                    SIGNATURE

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned, hereunto duly authorized.

                                         AVIRON

Dated: September 4, 2001                 By: /s/ C. Boyd Clarke
                                            -----------------------------------
                                            C. Boyd Clarke
                                            Chairman, President and Chief
                                            Executive Officer


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                                INDEX TO EXHIBITS

Exhibit 99.1   Press Release, dated September 3, 2001, entitled "Aviron Receives
               Complete Response Letter Following FDA Review of FluMist(TM) BLA"

EX-99.1

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                                                                    EXHIBIT 99.1

FOR IMMEDIATE RELEASE

                    AVIRON RECEIVES COMPLETE RESPONSE LETTER

                     FOLLOWING FDA REVIEW OF FLUMIST(TM) BLA

MOUNTAIN VIEW, CA -SEPTEMBER 3, 2001- Aviron (Nasdaq:AVIR) today announced the
receipt of a complete response letter on August 31, 2001 from the U.S. Food and
Drug Administration (FDA) relating to its Biologics License Application (BLA)
submitted on October 31, 2000 for licensure of FLUMIST(TM) . The Company is
seeking marketing approval of FLUMIST(TM) for the prevention of influenza in
healthy children and healthy adults.

In the complete response letter, the FDA requested additional information and
clarification regarding clinical and manufacturing data from the Company in
support of licensure of the product.

The Company will communicate with the FDA to clarify the FDA's requests in order
to establish a timeline for the submission of a response. The Company is
optimistic that it will be able to respond to the FDA's requests without
conducting additional clinical trials. After receiving the Company's response,
the FDA will establish a time period for review.

"This formal response to our BLA outlines the areas in which we will need to
work with the FDA in order to secure licensure of FLUMIST(TM)," said Boyd
Clarke, Aviron chairman and chief executive officer. "We look forward to working
closely with the FDA in order to fully respond to their requests."

Aviron is a biopharmaceutical company based in Mountain View, California,
focused on the prevention of disease through innovative vaccine technology.

This press release contains forward-looking statements. These statements, which
reflect management's current beliefs and expectations, are subject to risks and
uncertainties that may cause actual results to differ materially from those
projected in the forward-looking statements. Factors that could cause actual
results to differ include, but are not limited to, the risk that the FDA will
determine that the Company needs to conduct additional clinical trials and/or
provide additional data in order to obtain licensure, determine that the
Company's manufacturing facilities are not adequate or otherwise determine that
the Company's license application for FLUMISTTM is incomplete or inadequate to
approve the product for marketing to one or more target populations, and other
business risks identified in the Company's Annual Report on Form 10-K, as
amended, for the fiscal year ended December 31, 2000 and other quarterly
filings.

                                     -more-


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Additional information about the company, including recent press releases, can
be located at http://www.aviron.com.

For information, please contact:

Media:       John Bluth, Aviron                       650-919-3716
             Ben Butkus, Fleishman-Hillard            212-453-2000


Investors:   John Bluth, Aviron                       650-919-3716
             Fred Kurland, Aviron                     650-919-6666



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