The acquisition will see Emergent pay Sanofi $97.5m upfront and up to $27.5m based on regulatory and manufacturing-related milestones.
An Emergent spokesman told us the deal will also see the firm acquire a manufacturing facility Sanofi is setting up in Canton, Massachusetts and a leased facility in Rockville, Maryland, both in the US.
Emergent said it will also produce supplies of a bulk drug substance for a Sanofi, but did not provide additional details.
ACAM2000 is a vaccinia-based smallpox vaccine that was approved by the US FDA in 2007. It is the only product cleared for active immunization against smallpox disease for people deemed to be at greatest risk.
It is also approved in Australia and Singapore.
The US Centers for Disease Control and Prevention (CDC) originally contracted ACAM2000 developer Acambis – which was acquired by Sanofi in 2008 - to make the product for the US strategic national stockpile in 2000.
The supply deal has been extended several times and is currently valued at $425m.
Emergent said it will resume production of vaccine to fulfil the remainder of the contract – worth around $160m – in 2018 on the basis that the Canton the facility is approved by the US Food and Drug Administration (FDA).
The firm also said the deal will expand its contract manufacturing business through the addition of live viral manufacturing and fill/finish capabilities.