AVIR

Item 4 is hereby amended to add the following: On April 16, 2025, the Radoff/JEC Group entered into a letter agreement (the "Agreement") with the Issuer pursuant to which, among other things, the Issuer agreed to appoint Howard H. Berman, Ph.D. to the Board, effective immediately following the Issuer's 2025 annual meeting of stockholders (the "2025 Annual Meeting"), as a Class III director with a term expiring at the Issuer's 2026 annual meeting of stockholders (the "2026 Annual Meeting"). The Issuer also agreed to appoint Dr. Berman as an observer to the Board following the execution and delivery of the Agreement and until Dr. Berman's appointment to the Board. Additionally, pursuant to the Agreement, Franklin Berger will not stand for reelection to the Board as a Class I director when his term expires at the Issuer's 2027 annual meeting of stockholders. In connection with the Agreement, the Issuer also announced that the Board approved a share repurchase program with authorization to repurchase Shares having an aggregate value of up to $25.0 million. Pursuant to the Agreement, the Radoff/JEC Group is subject to certain customary standstill restrictions from the date of the Agreement until the earlier of (i) 30 days prior to the deadline for the submission of stockholder nominations of directors and business proposals for the 2026 Annual Meeting or (ii) 120 days prior to the first anniversary of the 2025 Annual Meeting (the "Restricted Period"), it being understood that the Issuer will be required to give sufficient advance notice to the Radoff/JEC Group in the event the Issuer determines to advance or delay the 2026 Annual Meeting, so that the Radoff/JEC Group will continue to have no less than 30 days to nominate at such meeting. Until the expiration of the Restricted Period, the Radoff/JEC Group agreed to vote all Shares beneficially owned by them (of which they have the right or ability to vote as of the applicable record date for such meeting) (i) in favor of the election of each person nominated by the Board for election as a director, (ii) against any stockholder nominations for directors that are not approved and recommended by the Board for election, (iii) against any proposals or resolutions to remove any member of the Board and (iv) in accordance with the recommendation of the Board on all other proposals or business that may be the subject of stockholder action; provided, however, that if Institutional Shareholder Services Inc. ("ISS") and Glass Lewis & Co., LLC ("Glass Lewis") recommend otherwise with respect to any proposals (other than as related to the election or removal of directors), each member of the Radoff/JEC Group is permitted to vote in accordance with such ISS and Glass Lewis recommendations; provided, further, that each member of the Radoff/JEC Group will be permitted to vote in its sole discretion on any proposal with respect to an Extraordinary Transaction (as defined in the Agreement). During the Restricted Period, the Radoff/JEC Group also agreed not to acquire an aggregate beneficial ownership of more than 6.0% of the outstanding Shares. The foregoing description of the Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Agreement, which is attached as Exhibit 99.1 hereto and is incorporated herein by reference.

Item 4 is hereby amended to add the following: On April 16, 2025, the Radoff/JEC Group entered into a letter agreement (the "Agreement") with the Issuer pursuant to which, among other things, the Issuer agreed to appoint Howard H. Berman, Ph.D. to the Board, effective immediately following the Issuer's 2025 annual meeting of stockholders (the "2025 Annual Meeting"), as a Class III director with a term expiring at the Issuer's 2026 annual meeting of stockholders (the "2026 Annual Meeting"). The Issuer also agreed to appoint Dr. Berman as an observer to the Board following the execution and delivery of the Agreement and until Dr. Berman's appointment to the Board. Additionally, pursuant to the Agreement, Franklin Berger will not stand for reelection to the Board as a Class I director when his term expires at the Issuer's 2027 annual meeting of stockholders. In connection with the Agreement, the Issuer also announced that the Board approved a share repurchase program with authorization to repurchase Shares having an aggregate value of up to $25.0 million. Pursuant to the Agreement, the Radoff/JEC Group is subject to certain customary standstill restrictions from the date of the Agreement until the earlier of (i) 30 days prior to the deadline for the submission of stockholder nominations of directors and business proposals for the 2026 Annual Meeting or (ii) 120 days prior to the first anniversary of the 2025 Annual Meeting (the "Restricted Period"), it being understood that the Issuer will be required to give sufficient advance notice to the Radoff/JEC Group in the event the Issuer determines to advance or delay the 2026 Annual Meeting, so that the Radoff/JEC Group will continue to have no less than 30 days to nominate at such meeting. Until the expiration of the Restricted Period, the Radoff/JEC Group agreed to vote all Shares beneficially owned by them (of which they have the right or ability to vote as of the applicable record date for such meeting) (i) in favor of the election of each person nominated by the Board for election as a director, (ii) against any stockholder nominations for directors that are not approved and recommended by the Board for election, (iii) against any proposals or resolutions to remove any member of the Board and (iv) in accordance with the recommendation of the Board on all other proposals or business that may be the subject of stockholder action; provided, however, that if Institutional Shareholder Services Inc. ("ISS") and Glass Lewis & Co., LLC ("Glass Lewis") recommend otherwise with respect to any proposals (other than as related to the election or removal of directors), each member of the Radoff/JEC Group is permitted to vote in accordance with such ISS and Glass Lewis recommendations; provided, further, that each member of the Radoff/JEC Group will be permitted to vote in its sole discretion on any proposal with respect to an Extraordinary Transaction (as defined in the Agreement). During the Restricted Period, the Radoff/JEC Group also agreed not to acquire an aggregate beneficial ownership of more than 6.0% of the outstanding Shares. The foregoing description of the Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Agreement, which is attached as Exhibit 99.1 hereto and is incorporated herein by reference.