COVID-19 vaccine pioneer Moderna (NSDQ:MRNA) is aiming to develop one of the first mRNA-based vaccines against respiratory syncytial virus (RSV).

Now, the FDA has granted fast track designation for mRNA-1345, an experimental single-dose mRNA RSV vaccine in adults 60 and older.

Pfizer (NYSE:PFE), Johnson & Johnson (NYSE:JNJ), GlaxoSmithKline (LON:GSK), Novavax (NSDQ:NVAX) and Bavarian Nordic (CPH:BAVA) are also developing RSV vaccines. None of those, however, use a mRNA platform.

RSV generally causes mild cold-like symptoms, according to the CDC, but can lead to serious illness in infants and the elderly. In infants, RSV frequently leads to pneumonia and another type of respiratory tract infection known as bronchiolitis.

Cambridge, Mass.–Moderna hopes to ultimately win regulatory approval to use the mRNA-1345 vaccine to “protect the most vulnerable populations – young children and older adults,” said Stéphane Bancel, CEO of Moderna, in a statement.

The company currently has a Phase 1 study underway, involving mRNA-1345 assessing its performance in younger adults, older adults and children.

The company currently has 11 vaccines for infectious diseases in human clinical trials.

The pandemic has increased Moderna’s capacity to develop drugs independently and sharpened its focus on infectious diseases.

Before it developed its mRNA-1273 COVID-19 vaccine, the company had relied on partners, including Merck, Alexion and AstraZeneca, to assist with drug development.

Moderna has won fast track designation for other investigational therapies including its COVID-19 vaccine, Zika vaccine candidate (mRNA-1893), methylmalonic acidemia (MMA) (mRNA-3704) and propionic acidemia (mRNA-3927) programs.