RSV is a highly contagious seasonal virus that can cause severe symptoms in infants and the elderly that causes around 60,000–160,000 hospitalisations and 6,000–10,000 deaths per year in the US, according to official estimates.

There are already two approved vaccines for those aged 60 and over, by GSK and Pfizer, both of which have been on the market since last year.

“The FDA approval of our second product, mRESVIA, builds on the strength and versatility of our mRNA platform,” said Stephane Bancel, chief executive officer of the US biotech firm, in a statement.

“mRESVIA protects older adults from the severe outcomes of RSV infection,” he continued, adding that unlike its competitors, Moderna’s shot was available in pre-filled syringes to reduce the risk of clinical errors.

GSK and Pfizer’s vaccines rely on traditional recombinant protein technology, introducing a pathogen component to the immune system to trigger a response.

In contrast, Moderna’s vaccine utilises cutting-edge messenger RNA (mRNA) technology, instructing the body to produce a unique protein that stimulates an immune response, teaching it to defend against the infection.

The approval was based on positive trial data published in the New England Journal of Medicine in December.

A global study of approximately 37,000 people aged 60 and older found the shot had an efficacy of 83.7% against lower respiratory tract disease – meaning when an RSV becomes more severe and can cause pneumonia, bronchitis, shortness of breath, and more.

There were no serious safety concerns, with common side effects including pain at the injection site, fatigue, headache, body aches, and joint stiffness.

Moderna said it expected the vaccines to be available for the 2024-2025 RSV season, and had filed for approval with regulators around the world.