X0306 4 2022-01-03 0 0001786255 Icosavax, Inc. ICVX 0001900372 Shiver John W. C/O ICOSAVAX, INC. 1616 EASTLAKE AVENUE E., SUITE 208 SEATTLE WA 98102-3793 1 0 0 0 Common Stock 2022-01-03 4 A 0 8500 0.00 A 8500 D Stock Option (Right to Buy) 22.50 2022-01-03 4 A 0 25500 0.00 A 2032-01-02 Common Stock 25500 25500 D Represents restricted stock units ("RSUs") granted on January 3, 2022. 1/3 of the total number of RSUs granted vest on each of the first three anniversaries of January 3, 2022, the vesting commencement date, subject to the reporting person's continued service on the applicable vesting date. Vesting of the RSUs shall accelerate upon a Change of Control (as defined in the Icosavax, Inc. 2021 Incentive Award Plan). Each RSU represents a contingent right to receive one share of common stock of the Issuer. 1/36th of the shares subject to the option vest monthly following January 3, 2022, the vesting commencement date. /s/ Elizabeth Bekiroglu, Attorney-in-Fact 2022-01-05