Novavax shares (NVAX) soared over 29% on Monday after the Canadian government agreed to pay the biotech firm nearly $350 million to cancel supplies of some previously ordered COVID-19 vaccines.

The company said in a regulatory filing that both parties filed an amendment to the agreement struck in January 2021. The updated agreement called for Canada to make two payments, the first after the amendment is implemented and the second after Novavax delivers the remaining doses of the vaccine in the second half of this year.

In addition, the agreement required Novavax to manufacture the shots at Canada’s Biologics Manufacturing Center (BMC) in Montreal in 2024 and 2025.

The Canadian government has the right to terminate the agreement if the company does not obtain regulatory approval to use BMC by December 31, 2024 or earlier.

Despite Monday’s gains, Novavax shares were still down close to 10% year-to-date.