X0306 4 2022-02-10 0 0001786255 Icosavax, Inc. ICVX 0001873839 Simpson Adam K. C/O ICOSAVAX, INC. 1616 EASTLAKE AVENUE E., SUITE 208 SEATTLE WA 98102 1 1 0 0 Chief Executive Officer Common Stock 2022-02-10 4 A 0 75578 0.00 A 291271 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) 17.55 2022-02-10 4 A 0 317866 0.00 A 2032-02-09 Common Stock 317866 317866 D Represents restricted stock units ("RSUs") which will vest as to 25% of the total number of RSUs granted on each of the first four anniversaries of February 10, 2022, subject to the reporting persons continued service through the applicable vesting date. Each RSU represents a contingent right to receive one share of common stock of the Issuer and the RSUs have no expiration date. 25% of the shares subject to the option will vest on February 10, 2023, and 1/48th of the shares subject to the option vest monthly thereafter, subject to the reporting person's continued service through the applicable vesting date. /s/ Elizabeth Bekiroglu, Attorney-in-Fact for Adam K. Simpson 2022-02-14