X0306 4 2022-12-21 0 0001786255 Icosavax, Inc. ICVX 0001873839 Simpson Adam K. C/O ICOSAVAX, INC. 1930 BOREN AVE., SUITE 1000 SEATTLE WA 98101 1 1 0 0 Chief Executive Officer Common Stock 2022-12-21 4 S 0 66764 8.963 D 225105 D Common Stock 2022-12-23 4 M 0 14369 0.84 A 239474 D Common Stock 531576 I By family trust Common Stock 129032 I By family trust Common Stock 129032 I By family trust Stock Option (Right to Buy) 0.84 2022-12-23 4 M 0 14369 0.00 D 2030-05-10 Common Stock 14369 33527 D Represents the sale by the Reporting Person, pursuant to a Rule 10b5-1 trading plan, of a portion of the shares of the Issuer purchased by the Reporting Person via exercise of incentive stock options during 2022. These shares are being sold by the Reporting Person prior to the end of 2022 in order to trigger a disqualifying disposition of such shares and to eliminate the alternative minimum tax that would otherwise arise as a result of the Reporting Person's exercise of such incentive stock options during 2022, with the remainder of the purchased shares continued to be held by the Reporting Person. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.54 to $9.41. The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. 25% of the shares subject to the option vested on 2/21/2021, and 1/48th of the shares subject to the option vest monthly thereafter. /s/ Elizabeth Bekiroglu, Attorney-in-Fact 2022-12-23