X0206 3 2021-07-28 0 0001786255 Icosavax, Inc. ICVX 0001121404 Sanofi 54, RUE LA BOETIE PARIS I0 75008 FRANCE 0 0 1 0 Series A-1 Preferred Stock (par value, $0.0001) 0.00 Common Stock 3003224 I Through its wholly-owned subsidiary, Aventis, Inc. Series B-1 Preferred Stock (par value, $0.0001) 0.00 Common Stock 85278 I Through its wholly-owned subsidiary, Aventis, Inc. The shares of Series A-1 Preferred Stock and Series B-1 Preferred Stock are convertible, at any time at the holder's election, to shares of the Issuer's Common Stock, as shown in Column 3, at a ratio of 4.1557-for-1. In addition, effective immediately prior to the closing of the Issuer's initial public offering of its Common Stock, each share of Series A-1 Preferred Stock and Series B-1 Preferred Stock will automatically convert to shares of the Issuer's Common Stock at a ratio of 4.1557-for-1 as shown in Column 3. The Series A-1 Preferred Stock and Series B-1 Preferred Stock have no expiration date. Sanofi is the beneficial owner of 3,003,224 Shares of Series A-1 Preferred Stock and 85,278 Shares of Series B-1 Preferred Stock of the Issuer through its wholly owned subsidiary, Aventis, Inc. /s/ Alexander Roger, Head of Securities Law and Capital Markets 2021-07-28