X0306 4 2021-07-30 0 0001786255 Icosavax, Inc. ICVX 0001874371 Holtzman Douglas C/O ICOSAVAX, INC. 1616 EASTLAKE AVENUE E., SUITE 208 SEATTLE WA 98102 0 1 0 0 Chief Scientific Officer Common Stock 2021-07-30 4 A 0 41500 15.00 A 282482 D Common Stock 2021-08-02 4 C 0 52440 0.00 A 52440 I By Stanley Holtzman Series A-1 Preferred Stock 0.00 2021-08-02 4 C 0 206323 D Common Stock 49648 0 I By Stanley Holtzman Series B-1 Preferred Stock 0.00 2021-08-02 4 C 0 11602 D Common Stock 2791 0 I By Stanley Holtzman Represents restricted stock units ("RSUs") granted on July 30, 2021, 25% of the total number of RSUs granted vest on each of the first four anniversaries of July 28, 2021, the vesting commencement date, subject to the reporting person's continued service on the applicable vesting date. Vesting of the RSUs shall accelerate as provided in the reporting person's offer letter. Each RSU represents a contingent right to receive one share of common stock of the Issuer. Includes an additional share of Common Stock as a result of the conversion of Preferred Stock calculated on an aggregate basis of all shares of Preferred Stock held by the holder. On August 2, 2021, the shares of Series A-1 Preferred Stock and Series B-1 Preferred Stock automatically converted into shares of the Issuer's Common Stock, for no additional consideration, at a ratio of 4.1557-for-1 share, immediately prior to the consummation of the Issuer's initial public offering. Douglas Holtzman, Ph.D. holds power-of-attorney (POA) over the shares owned by Stanley Holtzman. As POA, Dr. Holtzman holds voting and dispositive control over such shares. Dr. Holtzman disclaims beneficial ownership of the shares over which he has POA except to the extent of any pecuniary interest therein. /s/ Thomas Russo, Attorney-in-Fact 2021-08-02