X0306 4 2021-07-30 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 2021-07-30 4 A 0 125000 15.00 A 125000 D Common Stock 781576 I By family trust Common Stock 4032 I By family trust Common Stock 4032 I By family trust 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. /s/ Thomas Russo, Attorney-in-Fact 2021-08-02