Pfizer has received the US Food and Drug Administration (FDA) Breakthrough Therapy Designation (BTD) for its vaccine candidate, RSVpreF, to prevent respiratory syncytial virus (RSV) in the older population.

The breakthrough status indicates RSVpreF for preventing lower respiratory tract disease caused by RSV in the older population, aged 60 years and above.

RSV is a common respiratory virus that causes mild, flu-like symptoms in most adults, but may result in severe consequences for infants and older adults.

Pfizer has developed its potential RSV vaccine candidate based on basic foundational science discoveries, including those made at the National Institutes of Health (NIH).

After the key discovery, the company has tested several versions of the viral protein to identify the candidate with a strong anti-viral immune response.

The vaccine candidate has been designed to contain two preF proteins to ensure optimised protection against RSV A and B variants.

Pfizer senior vice president and vaccine R&D head Kathrin Jansen said: “Today’s decision is a significant step forward in our efforts to help protect vulnerable populations, particularly older adults, against certain potentially serious respiratory illnesses, including RSV.

“The clinical and economic burden of RSV represents a critical need, and we look forward to our ongoing dialogue with the FDA to accelerate the development of our RSV vaccine candidate.”

The FDA designation is based on the positive results from a proof-of-concept, Phase 2a study evaluating a single dose of 120µg RSVpreF in healthy adults aged 18 to 50 years.

It was also supported by the ongoing Phase 3 RENOIR trial of single-dose RSVpreF in adults ages 60 years or older, which was initiated in September last year.

Earlier this month, RSVpreF received FDA BTD to prevent RSV-associated lower respiratory tract disease in infants as young as newborn to up to six months.

The earlier FDA designation was based on results from the Phase 2b proof-of-concept study of RSVpreF in vaccinated pregnant women aged 18 to 49 and their infants.

The FDA designation follows Fast Track status granted to RSVpreF in November 2018.