Update Potential Combination of Poolbeg & HOOKIPA

Further to the announcement on 2 January 2025 (the "2.4 Announcement"), the Boards of Poolbeg and HOOKIPA are pleased to confirm that significant HOOKIPA shareholder, Gilead Sciences Inc. ("Gilead"), has indicated its intention to vote consistent with the HOOKIPA Board's recommendation if a formal offer were to be made and to participate in the proposed concurrent Fundraise, consistent with its current contractual obligations. Gilead owns 1,875,947 HOOKIPA common shares, representing 19.4% of HOOKIPA's existing issued share capital.

Additionally, HOOKIPA has amended the details of the Fundraise that were disclosed in the 2.4 Announcement. HOOKIPA is now expected to undertake a 100% primary private placement fundraise of approximately $30 million+. The 2.4 Announcement stated that HOOKIPA is expected to undertake a 100% private placement fundraise of up to approximately $30 million. An updated version of the Fundraise Presentation will be available on both companies' websites in due course.

Oppenheimer & Co. Inc. has been engaged by HOOKIPA as placement agent in connection with the private placement fundraise.

All discussions relating to the Potential Combination to date have been non-binding and on a non-exclusive basis, and there can be no assurance that a firm offer will be made or that any transaction will be completed.

Capitalised terms used but not defined in this announcement have the same meanings given to them in the 2.4 Announcement.

Important Additional Information

If a firm offer is made or the parties otherwise agree to binding terms with respect to the Potential Combination, HOOKIPA expects to file a proxy statement on Schedule 14A, including any amendments and supplements thereto (the "Proxy Statement") with the SEC. To the extent the parties effect the Potential Combination as a scheme of arrangement under the laws of England and Wales (the "Scheme"), the Proxy Statement will include a Scheme Document and the offer and issuance of shares by HOOKIPA to Poolbeg shareholders would not be expected to require registration under the U.S. Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder (the "Securities Act"), pursuant to an exemption provided by Section 3(a)(10) under the Securities Act. In the event that the parties determine to conduct the Potential Combination in a manner that is not exempt from the registration requirements of the Securities Act, HOOKIPA would file a registration statement with the SEC containing a prospectus with respect to the issuance of its shares. This announcement is not a substitute for the Proxy Statement or any other document that HOOKIPA may file with the SEC or send to its shareholders in connection with the Potential Combination. INVESTORS AND SHAREHOLDERS ARE URGED TO READ THE PROXY STATEMENT (INCLUDING THE SCHEME DOCUMENT) ANY AMENDMENTS OR SUPPLEMENTS THERETO AND OTHER RELEVANT DOCUMENTS FILED OR TO BE FILED WITH THE SEC IN CONNECTION WITH THE POTENTIAL COMBINATION, INCLUDING ANY DOCUMENTS INCORPORATED BY REFERENCE THEREIN, CAREFULLY IF AND WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PARTIES TO THE SCHEME, THE POTENTIAL COMBINATION AND RELATED MATTERS.

The Proxy Statement, if and when filed, as well as HOOKIPA's other public filings with the SEC, may be obtained without charge at the SEC's website at www.sec.gov and at HOOKIPA's website at www.hookipapharma.com. HOOKIPA shareholders and investors will also be able to obtain, without charge, a copy of the Proxy Statement (including the Scheme Document) and other relevant documents (when available) by directing a written request to HOOKIPA Pharma Inc., Attn: Corporate Secretary, 350 Fifth Avenue, 72nd Floor, Suite 7240, New York, NY 10118, USA.

Participants in the Solicitation

HOOKIPA and its directors and executive officers may be deemed "participants" in any solicitation of proxies from HOOKIPA's shareholders with respect to the Potential Combination. Information regarding the identity of HOOKIPA's directors and executive officers, and their direct and indirect interests, by security holdings or otherwise, in HOOKIPA securities is contained in HOOKIPA's Definitive Proxy Statement on Schedule 14A for HOOKIPA's 2024 annual meeting of shareholders, which was filed with the SEC on April 26, 2024. Information regarding subsequent changes to the holdings of HOOKIPA's securities by HOOKIPA's directors and executive officers can be found in filings on Forms 3, 4, and 5, which are available on HOOKIPA's website at www.hookipapharma.com or through the SEC's website at www.sec.gov. Additional information regarding the identity of potential participants, and their direct or indirect interests, by security holdings or otherwise, will be set forth in the Proxy Statement relating to the Potential Combination if and when it is filed with the SEC. The Proxy Statement, if and when filed, as well as HOOKIPA's other public filings with the SEC, may be obtained without charge at the SEC's website at www.sec.gov and at HOOKIPA's website at www.hookipapharma.com. Poolbeg's annual report for the year ended 31 December 2023, as well as Poolbeg's other regulatory announcements, may be obtained without charge at Poolbeg's website at www.poolbegpharma.com.