X0609 4 2026-10-01 0001326190 Altimmune, Inc. ALT 0002156820 MENZIUSO RICHARD THOMAS false 910 CLOPPER ROAD SUITE 201S GAITHERSBURG MD 20878 false true false false Principal Accounting Officer 0 Stock Options (option to buy) 2.76 2026-10-01 4 A 0 84546 0 A 2036-10-01 Common Stock, par value $0.0001 84546 84546 D Restricted Stock Units 2026-10-01 4 A 0 36234 0 A Common Stock, par value $0.0001 36234 36234 D The shares underlying the option become vested and exercisable over four (4) years with 25% of the shares vesting on October 1, 2027, with the remainder vesting in equal monthly installments for the following thirty-six (36) months, subject to the reporting person's continued service on each applicable vesting date. Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.0001, when vested. The RSUs become vested over four (4) years with 25% of the shares vesting on October 1, 2027, with the remainder vesting in equal annual installments for the following three (3) years, subject to the reporting person's continued service through the applicable vesting date, and have no expiration dat. /s/ Gregory Weaver, as Attorney-in-Fact 2026-10-02