X0508 4 2023-01-04 0 0001786255 Icosavax, Inc. ICVX 0001874021 Kanesa-thasan Niranjan C/O ICOSAVAX, INC. 1930 BOREN AVE., SUITE 1000 SEATTLE WA 98101 0 1 0 0 Chief Medical Officer 0 Common Stock 2023-01-04 4 M 0 13806 0.84 A 237786 D Common Stock 2023-01-04 4 M 0 74648 1.04 A 312434 D Common Stock 2023-01-04 4 M 0 11947 5.90 A 324381 D Common Stock 2023-01-04 4 M 0 5972 15.00 A 330353 D Common Stock 2023-01-04 4 S 0 106373 15.7038 D 223980 D Stock Option (Right to Buy) 0.84 2023-01-04 4 M 0 13806 0.00 D 2030-08-06 Common Stock 13806 2511 D Stock Option (Right to Buy) 1.04 2023-01-04 4 M 0 74648 0.00 D 2031-01-28 Common Stock 74648 42193 D Stock Option (Right to Buy) 5.90 2023-01-04 4 M 0 11947 0.00 D 2031-04-11 Common Stock 11947 108369 D Stock Option (Right to Buy) 15.00 2023-01-04 4 M 0 5972 0.00 D 2031-07-27 Common Stock 5972 118528 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.70 to $15.78. 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 April 1, 2021, and 1/48th of the shares subject to the option vest monthly thereafter. 25% of the shares subject to the option vested on January 14, 2022, and 1/48th of the shares subject to the option vest monthly thereafter. 25% of the shares subject to the option vested on March 19, 2022, and 1/48th of the shares subject to the option vest monthly thereafter. 1/48th of the shares subject to the option vest monthly following July 28, 2021, the vesting commencement date. /s/ Elizabeth Bekiroglu, Attorney-in-Fact 2024-01-05