EXHIBIT A

AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13D need to be filed with respect to the ownership by each of the undersigned of shares of Common Stock of HilleVax, Inc.

Date: May 6, 2022	FRAZIER LIFE SCIENCES PUBLIC FUND, L.P.
	By: FHMLSP, L.P., its General Partner
	By: FHMLSP, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 6, 2022	FHMLSP, L.P.
	By: FHMLSP, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 6, 2022	FHMLSP, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 6, 2022	FRAZIER LIFE SCIENCES X, L.P.
	By: FHMLS X, L.P., its General Partner
	By: FHMLS X, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 6, 2022	FHMLS X, L.P.
	By: FHMLS X, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 6, 2022	FHMLS X, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer

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Date: May 6, 2022	By:	*
		James N. Topper
Date: May 6, 2022	By:	*
		Patrick J. Heron
Date: May 6, 2022	By:	**
		Albert Cha
Date: May 6, 2022	By:	**
		James Brush
Date: May 6, 2022	By:	/s/ Steve R. Bailey
		Steve R. Bailey, as Attorney-in-Fact

* This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on March 29, 2016.

** This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on August 16, 2021.

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