Exhibit 5.1

	Goodwin Procter llp
	The New York Times Building
	620 Eighth Avenue
	New York, NY 10018
	goodwinlaw.com
	+1 212 813 8800

June 1, 2023

HOOKIPA Pharma Inc.

350 Fifth Avenue, 72nd Floor, Suite 7240

New York, New York

Re:         Securities Registered under Registration Statement on Form S-3

We have acted as counsel to you in connection with your filing of a Registration Statement on Form S-3 (File No. 333-266104) (as amended or supplemented, the “Registration Statement”) filed on July 12, 2022 with the Securities and Exchange Commission (the “Commission”) pursuant to the Securities Act of 1933, as amended (the “Securities Act”), relating to the registration of the offering by HOOKIPA Pharma Inc, a Delaware corporation (the “Company”) of up to $200,000,000 of any combination of securities of the types specified therein. The Registration Statement was declared effective by the Commission on July 21, 2022. Reference is made to our opinion letter dated July 12, 2022 and included as Exhibit 5.1 to the Registration Statement. We are delivering this supplemental opinion letter in connection with the prospectus supplement (the “Prospectus Supplement”) filed on June 1, 2023 by the Company with the Commission pursuant to Rule 424 under the Securities Act. The Prospectus Supplement relates to the offering by the Company of (1) up to 22,900,768 shares (the “Shares”) of the Company’s Common Stock, par value $0.0001 per share (“Common Stock”), (2) 15,268 shares of the Company’s Series A-2 Convertible Preferred Stock (the “Preferred Stock”) and (3) 15,268,000 shares of Common Stock issuable upon conversion of the Preferred Stock (the “Conversion Shares”), each as covered by the Registration Statement. The Shares are being sold to the underwriters named in, and pursuant to, an underwriting agreement among the Company and such underwriters (the “Underwriting Agreement”).

We have reviewed such documents and made such examination of law as we have deemed appropriate to give the opinions set forth below. We have relied, without independent verification, on certificates of public officials and, as to matters of fact material to the opinions set forth below, on certificates of officers of the Company.

For purposes of the opinion set forth below, we have assumed that (i) before the Shares are issued the Company does not issue shares of Common Stock or reduce the total number of shares of Common Stock the Company is authorized to issue under its certificate of incorporation such that the number of unissued shares of Common Stock authorized under the Company’s certificate of incorporation is less than the number of Shares, and (ii) no event occurs that causes the number of authorized shares of Common Stock available for issuance by the Company to be less than the number of then unissued Conversion Shares issuable upon conversion of the Preferred Stock.

HOOKIPA Pharma, Inc.

June 1, 2023

Page 2

The opinion set forth below is limited to the Delaware General Corporation Law.

Based on the foregoing, we are of the opinion that (i) the Shares and the Preferred Stock have been duly authorized and, when delivered and paid for in accordance with the terms of the Underwriting Agreement, will be validly issued, fully paid and non-assessable and (ii) the Conversion Shares, when issued upon the conversion of the Preferred Stock in accordance with the terms of the Preferred Stock, will be validly issued, fully paid and non-assessable.

This opinion letter and the opinion it contains shall be interpreted in accordance with the Core Opinion Principles as published in 74 Business Lawyer 815 (Summer 2019).

We hereby consent to the inclusion of this opinion as Exhibit 5.1 to the Registration Statement and to the references to our firm under the caption “Legal Matters” in the Registration Statement. In giving our consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations thereunder.