AstraZeneca’s investigational vaccine for respiratory syncytial virus (RSV) has been granted “breakthrough therapy” designation by the FDA and “prime” designation by the European Medicines Agency, according to the company.

The “Breakthrough Therapy” and “Prime” designations in the United States and Europe respectively were based on early results from Phase IIb trials of MEDI8897, AstraZeneca said.

MEDI8897, which is being developed in partnership with Sanofi Pasteur, only requires one dose during a typical five month RSV season, AstraZeneca said.