Exhibit 5.1

Hogan Lovells US LLP Harbor East 100 International Drive Suite 2000 Baltimore, MD 21202 T +1 410 659 2700 F +1 410 659 2701 www.hoganlovells.com

March 28, 2024

Board of Directors

Vaccinex, Inc.

1895 Mount Hope Avenue

Rochester, NY 14620

To the addressee referred to above:

We are acting as counsel to Vaccinex, Inc., a Delaware corporation (the “Company”), in connection with its registration statement on Form S-3, as amended (File No. 333-271074) (the “Registration Statement”) filed with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Act”), relating to the public offering of 193,000 shares of the common stock, par value $0.0001 per share, of the Company (the “Shares”). The Shares are to be sold pursuant to a Securities Purchase Agreement between the Company and each purchaser named therein (the “Agreement”), as described in the prospectus, dated April 12, 2023 (the “Base Prospectus”), which forms a part of the Registration Statement, as supplemented by the Prospectus Supplement, dated March 27, 2024 (the “Prospectus Supplement”, and together with the Registration Statement, the “Prospectus”). This opinion letter is furnished to you at your request to enable you to fulfill the requirements of Item 601(b)(5) of Regulation S-K, 17 C.F.R. § 229.601(b)(5), in connection with the Registration Statement.

For purposes of this opinion letter, we have examined copies of such agreements, instruments and documents as we have deemed an appropriate basis on which to render the opinions hereinafter expressed. In our examination of the aforesaid documents, we have assumed the genuineness of all signatures, the legal capacity of all natural persons, the accuracy and completeness of all documents submitted to us, the authenticity of all original documents, and the conformity to authentic original documents of all documents submitted to us as copies (including pdfs). As to all matters of fact, we have relied on the representations and statements of fact made in the documents so reviewed, and we have not independently established the facts so relied on. This opinion letter is given, and all statements herein are made, in the context of the foregoing.

This opinion letter is based as to matters of law solely on the Delaware General Corporation Law, as amended, and as to the opinion expressed in paragraph (b) below, the laws of the State of New York (but not including any laws, statutes, ordinances, administrative decisions, rules or regulations of any political subdivision below the state level). We express no opinion herein as to any other statutes, rules or regulations.

Hogan Lovells US LLP is a limited liability partnership registered in the state of Delaware. “Hogan Lovells” is an international legal practice that includes Hogan Lovells US LLP and Hogan Lovells International LLP, with offices in: Alicante Amsterdam Baltimore Beijing Birmingham Boston Brussels Colorado Springs Denver Dubai Dusseldorf Frankfurt Hamburg Hanoi Ho Chi Minh City Hong Kong Houston Johannesburg London Los Angeles Luxembourg Madrid Mexico City Miami Milan Minneapolis Monterrey Munich New York Northern Virginia Paris Philadelphia Rome San Francisco São Paulo Shanghai Silicon Valley Singapore Sydney Tokyo Warsaw Washington, D.C. Associated Offices: Budapest Jakarta Riyadh Shanghai FTZ Ulaanbaatar. Business Service Centers: Johannesburg Louisville. Legal Services Center: Berlin. For more information see www.hoganlovells.com

Based upon, subject to and limited by the foregoing, we are of the opinion that following (1) issuance of the Shares pursuant to the terms of the Agreement and (2) receipt by the Company of the consideration for the Shares specified in the resolutions of the Board of Directors of the Company or the Pricing Committee of the Board of Directors, the Shares will be validly issued, fully paid, and nonassessable.

This opinion letter has been prepared for use in connection with the filing by the Company of a Current Report on Form 8-K on the date hereof relating to the offer and sale of the Shares, which Form 8-K will be incorporated by reference into the Registration Statement and Prospectus, and speaks as of the date hereof. We assume no obligation to advise of any changes in the foregoing subsequent to the effective date of the delivery of this letter.

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Prospectus Supplement and to the reference to this firm under the caption “Legal Matters” in the Prospectus Supplement. In giving this consent, we do not thereby admit that we are an “expert” within the meaning of the Act.

Very truly yours,

/s/ Hogan Lovells US LLP

HOGAN LOVELLS US LLP