LIMITED POWER OF ATTORNEY FOR

SECTION 16 REPORTING PURPOSES



      Know all by these presents, that the undersigned hereby

makes, constitutes and appoints William Enright, Ori Solomon,

and Louis Rambo, each acting individually, as the undersigned's

true and lawful attorneys-in-fact, with full power and authority

as hereinafter described on behalf of and in the name, place and

stead of the undersigned to:



(1) execute for, and on behalf of, the

undersigned, in the undersigned's capacity as an officer, director

and/or 10% beneficial owner of Altimmune, Inc. (the "Company"),

Forms 3, 4, and 5 in accordance with Section 16(a) of the

Securities Exchange Act of 1934 and the rules and regulations

promulgated thereunder (the "Exchange Act");



(2) seek or obtain, as the undersigned's

representative and on the undersigned's behalf, information on

transactions in the Company's securities from any third party,

including brokers, employee benefit plan administrators and trustees,

and the undersigned hereby authorizes any such person to release

any such information to any attorney-in-fact and further approves

and ratifies any such release of information;



(3) do and perform any and all acts for and on

behalf of the undersigned that may be necessary or desirable to

prepare, complete and execute any such Form 3, 4 or 5, and any

amendments thereto, or other required report and timely file such

Forms or reports with the United States Securities and Exchange

Commission (the "Commission"), the NASDAQ and any stock

exchange or similar authority as considered necessary or advisable

under Section 16(a) of the Exchange Act (including, without

limitation, executing and delivering a Form ID to the Commission to

obtain EDGAR filing codes); and



(4) take any other action of any type whatsoever in

connection with the foregoing which, in the opinion of such attorney-

in-fact, may be of benefit to, in the best interest of, or legally required

by, the undersigned, it being understood that the documents executed

by such attorney-in-fact on behalf of the undersigned pursuant to this

Limited Power of Attorney shall be in such form and shall contain

such terms and conditions as such attorney-in-fact may approve in

such attorney-in-fact's sole discretion.



 The undersigned hereby gives and grants to each such

attorney-in-fact full power and authority to do and perform any and

every act and thing whatsoever requisite, necessary, or proper to be

done in the exercise of any of the rights and powers herein granted, as

fully to all intents and purposes as the undersigned might or could do

if personally present, with full power of substitution or revocation,

hereby ratifying and confirming all that such attorney-in-fact, or such

attorney-in-fact's substitute or substitutes, shall lawfully do or cause to

be done by virtue of this power of attorney and the rights and powers

herein granted.



 The undersigned hereby acknowledges that (a) the

foregoing attorneys-in-fact are serving in such capacity at the request

of the undersigned; (b) this Limited Power of Attorney authorizes, but

does not require, each such attorney-in-fact to act in his or her

discretion on information provided to such attorney-in-fact without

independent verification of such information; (c) any documents

prepared and/or executed by any attorney-in-fact on behalf of the

undersigned pursuant to this Limited Power of Attorney shall be in

such form and shall contain such information and disclosure as such

attorney-in-fact, in his or her sole discretion, deems necessary or

advisable; (d) neither the Company nor any attorney-in-fact assumes

(i) any liability for the undersigned's responsibility to comply with the

requirements of the Exchange Act, (ii) any liability of the undersigned

for any failure to comply with such requirements or (iii) any obligation

or liability of the undersigned for profit disgorgement under Section

16(b) of the Exchange Act; and (e) this Limited Power of Attorney

does not relieve the undersigned from responsibility for compliance

with the undersigned's obligations under the Exchange Act, including,

without limitation, the reporting requirements under Section 16 of the

Exchange Act.



 This Limited Power of Attorney shall remain in full

force and effect until the undersigned is no longer required to file

Forms 3, 4, and 5 with respect to the undersigned's holdings of, and

transactions in, securities issued by the Company, unless earlier

revoked as to any attorney-in-fact by the undersigned in a signed

writing delivered to such attorney-in-fact.



 IN WITNESS WHEREOF, the undersigned has caused

this Power of Attorney to be executed as of this 29th day of May, 2018.



/s/ William M. Brown

William M. Brown