X0508 4 2023-07-31 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 1 Common Stock 2023-07-31 4 S 0 3323 8.8615 D 235864 D Reflects shares sold to cover withholding taxes upon vesting of restricted stock unit awards pursuant to a Rule 10b5-1 instruction letter dated December 23, 2021. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.71 to $9.11. 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. /s/ Elizabeth Bekiroglu, Attorney-in-Fact 2023-08-01