Moderna’s mRNA-based combination vaccine against both flu and COVID-19 has gotten the green light in Europe—but it continues to be shelved in the US, where it was developed.

This week, the European Commission authorized Moderna to market the vaccine, mRNA-1083 or mCOMBRIAX, making it the world’s first authorized combination shot for the two respiratory viruses. The decision follows a positive review in February from a key European Medicines Agency’s committee, which paved the way for the approval.

Moderna CEO Stéphane Bancel welcomed the news. “By combining protection against two significant respiratory viruses in a single dose, our vaccine aims to simplify immunization for adults, particularly those at high risk,” Bancel said in a press release. “mCOMBRIAX offers an important new option for Europeans, while also aiming to strengthen the resilience of healthcare systems across Europe.”

mCOMBRIAX combines Moderna’s COVID-19 vaccine with an investigational influenza vaccine called mRNA-1010, which is still under review in Europe. The combination shot was authorized based on findings from a Phase III clinical trial of around 4,000 adults. The trial contained two groups, one with participants aged 50 to 64 that included a comparison of a standard flu vaccine, and another aged 65 and up that included a comparison of a high-dose flu vaccine. In both groups, mCOMBRIAX spurred statistically-significant higher immune responses against common flu strains (A/H1N1, A/H3N2, and B/Victoria) and against SARS-CoV-2 than the comparator vaccines. There were no concerns over safety or adverse events.