Atossa Therapeutics, Inc.

2026 Annual Meeting Proxy Voting

MAY 7, 2026 AT 9:00 a.m. PACIFIC TIME

For stockholders of record as of March 19, 2026

THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS OF ATOSSA THERAPEUTICS, INC.

The undersigned stockholder(s) hereby appoint(s) Steven C. Quay, M.D., Ph.D., and Mark Daniel (the “Named Proxies”), each as proxies and attorneys-in-fact, with the power to act without the other and with the power to appoint his substitute, and hereby authorize(s) each to represent and to vote, as designated herein, all of the shares of common stock of Atossa Therapeutics, Inc., that the stockholder(s) is/are entitled to vote at the Annual Meeting of Stockholders to be held live via the Internet at 9:00 a.m. Pacific Time on May 7, 2026 and at any adjournments or postponements thereof. The Named Proxies are authorized to vote in their discretion upon such other matters that may properly come before the meeting or any adjournments or postponements thereof. You are encouraged to specify your choice by marking the appropriate box, but you need not mark any box if you wish to vote in accordance with the Board of Directors’ recommendations. The Named Proxies cannot vote your shares unless you sign and return this card.

In order to virtually attend the meeting, you must register at https://web.viewproxy.com/AtossaTherapeutics/2026 by 11:59 p.m. Eastern Time on May 5, 2026. On the day of the Annual Meeting of Stockholders, if you have properly registered, you may enter the meeting by clicking on the link provided and entering the password you received via email in your registration confirmation. Further instructions on how to attend and vote at the Annual Meeting of Stockholders are contained in the Proxy Statement.