Exhibit 31.4

Certification of Principal Executive Officer

Pursuant to SEC Rule 13a-14(a)/15d-14(a)

I, Elizabeth A. Czerepak, certify that:

1. I have reviewed this Amendment No. 1 to the annual report on Form 10-K of Altimmune, Inc. for the year ended December 31, 2017; and

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report.

Dated: April 30, 2018	/s/ Elizabeth A. Czerepak
	Name: Elizabeth A. Czerepak
	Title: Chief Financial Officer, Executive Vice President of Corporate Development and Secretary (principal financial officer)