AstraZeneca hasn’t given up on its lofty vaccine ambitions. 

The pharma will acquire biotech Icosavax in a deal worth up to $1.1 billion, under which AstraZeneca will boost its vaccine pipeline with a particular focus on products developed with Icosavax’s protein virus-like particle (VLP) platform.

Specifically, Icosavax brings its lead candidate, IVX-A12, a protein VLP vaccine for both respiratory syncytial virus (RSV) and human metapneumovirus (hMPV), under the AstraZeneca fold.

VLP vaccines work by mimicking how viruses trigger the immune system. AstraZeneca noted they may create a stronger immune response and greater breadth of protection as well as fewer side effects compared to the current adjuvanted RSV vaccine.

“This virus-like particle vaccine technology has the potential to transform prevention against severe infectious diseases, including RSV and hMPV,” said Iskra Reic, EVP of vaccines and immune therapies at AstraZeneca, in a statement.

Reic noted that IVX-A12 is Phase 3 ready, bringing a differentiated, advanced investigational vaccine to AstraZeneca’s late-stage pipeline. It would also serve as a platform for further development of combination vaccines against respiratory viruses.

“This aligns with our strategy to deliver a portfolio of therapies to address high unmet needs in infectious diseases, and our ambition to protect the most vulnerable patients who have high risk of severe outcomes,” Reic added.

AstraZeneca offered $800 million upfront in the transaction, with $15 for each Icosavax share. The pharma said it would provide an extra $5 in cash per share if milestones are met, which could bring the deal north of $1.1 billion.

While interest in updated COVID-19 vaccines and oral treatments has largely waned as the year has progressed, RSV has garnered increasing attention from drugmakers seeking to gain significant market share.

AstraZeneca nabbed an approval from the Food and Drug Administration for its preventive therapy developed jointly with Sanofi for RSV lower respiratory tract disease earlier this year as well. The Icosavax acquisition will allow the British pharma giant to jump right into the RSV vaccine race, given there are currently no combination vaccines for RSV.

The Icosavax acquisition comes months after GSK grabbed the first FDA approval for an adult RSV vaccine, with data showing Arexy was 94% effective against severe disease. 

Pfizer followed closely behind, winning an FDA nod at the end of May for its RSV vaccine Abrysvo in older adults. In August, the agency approved Abrysvo for pregnant people and children.