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                                               Filing Pursuant to Rule 424(b)(2)
                                            Registration Statement No. 333-87185




                          PROSPECTUS SUPPLEMENT NO. 10

                      (TO PROSPECTUS DATED OCTOBER 8, 1999)

                                     SHARES

                                     AVIRON

                                  COMMON STOCK

                                 ---------------

     You should read this prospectus supplement and the accompanying prospectus
carefully before you invest. Both documents contain information you should
consider carefully before making your investment decision.

     INVESTING IN OUR COMMON STOCK INVOLVES CERTAIN RISKS. SEE "RISK FACTORS"
BEGINNING ON PAGE 6.

                              PLAN OF DISTRIBUTION

     We are offering 262,200 shares of our common stock to Acqua Wellington
North American Equities Fund, Ltd. pursuant to this prospectus supplement. The
common stock will be purchased at a negotiated purchase price of $30.5111 per
share. We will not pay any other compensation in conjunction with the sale of
our common stock.

     Acqua Wellington and its pledgees, donees, transferees and other subsequent
owners, may offer their shares at various times in one or more of the following
transactions:

     -    in the over-the-counter market; or

     -    in privately negotiated transactions

at prevailing market prices at the time of sale, at prices related to those
prevailing market prices, at negotiated or at fixed prices.

     The transactions in the shares may be effected by one or more of the
following methods:

     -    ordinary brokerage transactions and transactions in which the broker
          solicits purchasers;

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     -    purchases by a broker or dealer as principal, and the resale by that
          broker or dealer for its account under this prospectus, including
          resale to another broker or dealer;

     -    block trades in which the broker or dealer will attempt to sell the
          shares as agent but may position and resell a portion of the block as
          principal in order to facilitate the transaction; or

     -    negotiated transactions between selling stockholders and purchasers
          without a broker or dealer.

     Acqua Wellington is an "underwriter" within the meaning of the Securities
Act in connection with its sale of the shares purchased from us described in
this prospectus supplement. Broker-dealers or other persons acting on the behalf
of parties that participate in the distribution of the shares may also be deemed
to be underwriters. Any commissions or profits they receive on the resale of the
shares may be deemed to be underwriting discounts and commissions under the
Securities Act.

     During the time Acqua Wellington is engaged in distributing shares covered
by this prospectus, Acqua Wellington will comply with the requirements of the
Securities Act and Rule 10b-5 and Regulation M under the Exchange Act. Under
those rules and regulations, they:

     -    may not engage in any stabilization activity in connection with our
          securities;

     -    must furnish each broker which offers shares of common stock covered
          by this prospectus with the number of copies of this prospectus which
          are required by each broker; and

     -    may not bid for or purchase any of our securities or attempt to induce
          any person to purchase any of our securities other than as permitted
          under the Exchange Act.

     In connection with Acqua Wellington's purchase and potential resale of the
shares covered by this prospectus supplement, we will agree to indemnify and
hold harmless Acqua Wellington and each person who controls Acqua Wellington
against certain liabilities, including liabilities under the Securities Act,
which may be based upon, among other things, any untrue statement or alleged
untrue statement of a material fact or any omission or alleged omission of a
material fact, unless made or omitted in reliance upon written information
provided to us by Acqua Wellington.

     We have agreed to bear the expenses incident to the registration of the
shares, other than selling discounts and commissions. These expenses are
estimated to be $100,000.

                                 USE OF PROCEEDS

     We will use the proceeds of this offering as described in the prospectus.
See "Use of Proceeds" beginning on page 11.


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                       WHERE YOU CAN FIND MORE INFORMATION

     The SEC allows us to "incorporate by reference" information that we file
with them, which means that we can disclose important information to you by
referring you to those documents. The information incorporated by reference is
an important part of this prospectus supplement and the accompanying prospectus.
We incorporate the documents listed below, in addition to those indicated on
page 2 of the prospectus:

     o    Report on Form 8-K dated January 11, 2000, filed with the SEC on
          January 14, 2000.

     o    Annual Report on Form 10-K for the year ended December 31, 1999, as
          amended by a Form 10-K/A filed with the SEC on April 3, 2000, and as
          amended by a Form 10-K/A filed with the SEC on April 28, 2000.

     o    Definitive Proxy Statement dated May 4, 2000, filed with the SEC on
          May 4, 2000, in connection with our 2000 Annual Meeting of
          Stockholders.

     o    Quarterly Report on Form 10-Q for the quarter ended March 31, 2000,
          filed with the SEC on May 15, 2000.

     o    Report on Form 8-K dated June 12, 2000, filed with the SEC on June 13,
          2000.

                           MARKET FOR OUR COMMON STOCK

     On August 4, 2000, the last reported sale price of our common stock on the
Nasdaq National Market was $30.5111 per share. Our common stock is listed on the
Nasdaq National Market under the symbol "AVIR." The common stock sold under this
prospectus supplement will be listed on the Nasdaq National Market after we
notify the Nasdaq National Market that the shares have been issued.

     As of August 4, 2000, we had 21,664,964 shares of common stock outstanding.

                                     GENERAL

     You should rely only on the information provided or incorporated by
reference in this prospectus supplement and the prospectus. We have not
authorized anyone else to provide you with different information. You should not
assume that the information in this prospectus supplement is accurate as of any
date other than the date on the front of these documents.

     NEITHER THE SECURITIES EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THE SECURITIES OR PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

            The date of this prospectus supplement is August 4, 2000.


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                                TABLE OF CONTENTS



                                                                  PAGE
                                                             
PROSPECTUS SUPPLEMENT
         Plan of Distribution .....................................S-1
         Use of Proceeds...........................................S-2
         Where You Can Find More Information.......................S-3
         Market for Our Common Stock...............................S-3
         General...................................................S-3

PROSPECTUS
         Where You Can Find More Information.........................2
         Summary.....................................................4
         The Company.................................................4
         The Offering................................................5
         Risk Factors................................................6
         Forward-Looking Statements.................................11
         Use of Proceeds............................................11
         Plan of Distribution.......................................13
         Legal Matters..............................................13
         Experts....................................................13



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