                                                        [**]                             [**] [**]   [**] [**] [**] [**]   5-26-2023 Certain identified information has been marked in the exhibit because it is both (i) not material and (ii) would likely cause competitive harm to the Company, if publicly disclosed. Double asterisks denote omissions.

                          [**][**] [**]    

The purpose of this modification is to exercise option 3001 for [**] doses of ACAM2000 to sustain operational capability of ACAM2000 for Fiscal Year (FY) 2023. 1. The period of performance for ACAM2000 product to be delivered for Task 1, under Option 3001 is updated from 10/01/21-10/30/22 to 10/31/22-6/30/23. 2. The minimum annual procurement order for this modification is [**] doses of ACAM2000 kits with a minimum shelf life of [**] with supply ranging from [**]. Quantities Shelf Life * [**] [**] [**] [**] [**] as of June 7, 2023 EPDG will provide the potency testing under CLIN 30001 for existing ACAM2000 doses in the SNS by [**]. Any further testing for ACAM2000 or Wetvax will be subject to future discussions. Funding is hereby obligated in the amount of [**] for [**] by doses at [**] per dose. The revised funding obligation amount will be increased from [**] by [**] to [**]. All other terms and conditions remain the same. 3 of 3 [**] [**] [**]