March 7 (Reuters) - AstraZeneca ( AZN ) and Sanofi's

antibody therapy was 90% effective in protecting

infants from hospitalizations associated with respiratory

syncytial virus (RSV), a U.S. CDC study showed.

The data is the first real-world evidence of effectiveness

of the therapy, nirsevimab, in protecting infants against

RSV-related hospitalization in their first season of potential

exposure to the virus.

The therapy, branded as Beyfortus, won the U.S. health

regulator's nod in July 2023.

Although the data available for analysis is limited, CDC

said the early estimates support the current recommendation of

use in infants.

In August, the CDC had recommended the use of the therapy in

infants below eight months of age born during or entering their

first RSV season, as well as in children aged 8-19 months who

remain vulnerable to severe RSV disease through their second

season.

The study looked at nearly 700 infants who were hospitalized

with acute respiratory illness, from October 2023 through

February 2024. Of those, 8% infants received the therapy more

than or at 7 days before experiencing symptoms.

The results also reflect a shorter surveillance period due

to the introduction of the product in August 2023, the agency

said, as well as limited supply of the therapy.

With increasing availability, the CDC said it will continue

to assess the effectiveness of the therapy over an entire

season.

Pfizer's ( PFE ) maternal RSV vaccine, Abrysvo, is also

available to prevent for young infants.

RSV, a common respiratory virus, is a leading cause of

hospitalizations in infants.