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

June 27, 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 (the “Registration Statement”), filed with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Act”), relating to the proposed public offering by the selling stockholders (the “Selling Stockholders”) listed in the Registration Statement of 490,509 shares (the “Shares”) of common stock, par value $0.0001 per share, of the Company (“Common Stock”), consisting of (i) 18,113 issued and outstanding shares of Common Stock (the “Common Shares”), (ii) 247,170 shares of Common Stock (the “Warrant Shares”) issuable to the Selling Stockholders upon the exercise of warrants (the “Warrants”) and (iii) 225,226 shares of Common Stock (the “Conversion Shares”) issuable to one of the Selling Stockholders upon conversion of shares of the Company’s Series A Preferred Stock (the “Preferred Shares”), all of which may be sold from time to time and on a delayed or continuous basis, as set forth in the prospectus which forms a part of the Registration Statement (the “Prospectus”), and as to be set forth in one or more supplements to 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. We have also assumed upon the issuance of the Warrant Shares and Conversion Shares, the total number of shares of Common Stock issued and outstanding will not exceed the total number of shares of Common Stock that the Company is then authorized to issue under its certificate of incorporation. This opinion letter is given, and all statements herein are made, in the context of the foregoing.

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 Berlin 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 Riyadh Rome San Francisco São Paulo Shanghai Silicon Valley Singapore Sydney Tokyo Warsaw Washington, D.C. Associated Offices: Budapest Jakarta Shanghai FTZ. Business Service Centers: Johannesburg Louisville. For more information see www.hoganlovells.com

Board of Directors

Vaccinex, Inc.

June 27, 2024

Page 2

This opinion letter is based as to matters of law solely on the applicable provisions of the Delaware General Corporation Law, as amended. We express no opinion herein as to any other statutes, rules or regulations (and in particular, we express no opinion as to any effect that such other statutes, rules or regulations may have on the opinions expressed herein).

Based upon, subject to and limited by the foregoing, we are of the opinion that, as of the date hereof, (i) the Shares have been duly authorized by all necessary corporate action on the part of the Company, (ii) the Common Shares have been validly issued and are fully paid and nonassessable, (iii) following (a) exercise of the Warrants in accordance with their terms, (b) receipt by the Company of the exercise price for the Warrant Shares as specified in the applicable Warrants, and (c) issuance of the Warrant Shares thereunder, the Warrant Shares will be validly issued, fully paid, and nonassessable, and (iv) following (a) conversion of the Preferred Shares in accordance with the terms of the Certificate of Designation of Series A Preferred Stock of the Company and (b) issuance of the Conversion Shares thereunder, the Conversion Shares will be validly issued, fully paid, and nonassessable.

This opinion letter has been prepared for use in connection with the Registration Statement. We assume no obligation to advise of any changes in the foregoing subsequent to the effective date of the Registration Statement.

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement and to the reference to this firm under the caption “Legal Matters” in the Prospectus. 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