US-based Emergent BioSolutions has entered an agreement to buy the ACAM2000, smallpox vaccine business of French pharmaceutical company Sanofi for up to $125m.

The total value of the contract comprises $97.5m upfront and up to $27.5m in near-term contingent regulatory and manufacturing-related milestones.

Smallpox is a highly contagious disease caused by the variola virus, a member of the Orthopox virus family.

ACAM2000 is the only vaccine licensed by the US Food and Drug Administration (FDA) that can be used for active immunisation against smallpox disease for people at high risk for smallpox infection.

The vaccine is designated for use in a bioterrorism emergency, with more than 230 million doses having already been delivered to the US Strategic National Stockpile.

The treatment is also licensed in Australia and Singapore and currently stockpiled both in the US and internationally.

Emergent BioSolutions president and CEO Daniel Abdun-Nabi said: "This transaction diversifies our portfolio and broadens our countermeasure franchise with a vaccine that is being stockpiled both in the US and internationally."

With the closing of the transaction, Emergent BioSolutions will also have an existing ten-year contract originally valued at up to $425m with the Centers for Disease Control and Prevention (CDC), with a remaining value of up to nearly $160m for supplying ACAM2000 to the Strategic National Stockpile (SNS).

In addition, the company will acquire a US-based cGMP bulk manufacturing facility and a lease to a cGMP fill / finish facility, also in the US, along with the existing staff of about 100 employees.

The company anticipates that the transaction will increase its contract manufacturing operations through the addition of live viral manufacturing and fill / finish capabilities, as well as the execution of a contract manufacturing agreement to deliver bulk drug substance for one of Sanofi’s commercial vaccines.

Subject to customary closing conditions including antitrust regulatory approval, the transaction is expected to conclude this year.