AGREEMENT

EXHIBIT 99.1

AGREEMENT

In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that this Statement on Schedule 13G relating to the Common Stock of Altimmune, Inc. is being filed with the Securities and Exchange Commission on behalf of each of them.

February 16, 2021

	XXXXX BROS. ADVISORS LP By: Xxxxx Bros. Advisors (GP) LLC, its general partner
	By:	/s/ Xxxxx X. Xxxxxxx
		Name: Xxxxx X. Xxxxxxx Title: President

	XXXXX BROS. ADVISORS (GP) LLC
	By:	/s/ Xxxxx X. Xxxxxxx
		Name: Xxxxx X. Xxxxxxx Title: President

/s/ Xxxxxx X. Xxxxx

Xxxxxx X. Xxxxx

/s/ Xxxxx X. Xxxxx

Xxxxx X. Xxxxx