Moderna in the Drug Discovery & Development Pharma 50The U.S. government will pay $1.74 billion to buy 66 million doses of Moderna’s COVID-19 vaccine made with the new omicron-adapted formula, the drugmaker said today.

The government has the option to acquire up to 300 million total doses of the omicron boosters under the agreement.

The U.S. last month agreed to buy 105 million doses of Pfizer and BioNTech’s updated vaccine for $3.2 billion. That deal similarly includes an option for up to 300 million doses.

Moderna is developing the bivalent vaccine candidate mRNA-1273.222 based on feedback from the FDA. The vaccine incorporates mRNA from the omicron BA.4/5 strain.

“Moderna’s mRNA platform is enabling us to rapidly create mRNA-1273.222, a bivalent vaccine that specifically targets omicron subvariants BA.4 and BA.5, the most prevalent variants of concern in the U.S. today,” Moderna CEO Stéphane Bancel said in a news release.

Scientists are uncertain whether BA.4/BA.5–based vaccines are likely to remain effective if another strain dominates in the fall or winter. The BA.5 sublineage is a “moving target,” Dr. Anthony Fauci, chief medical advisor to President Joe Biden, said in an interview with The Hill.

The federal government is also making an additional 786,000 monkeypox vaccine doses available after distributing about 300,000 vaccine doses in July.