Nirsevimab
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A lab-made antibody that locks onto RSV's surface protein before it can change shape to infect cells, protecting infants from severe RSV illness for months after a single dose.
How it works
RSV infects cells using a surface protein that has to flip into a new shape to fuse with a cell and get inside — nirsevimab locks onto that protein while it's still in its original, pre-fusion shape, jamming it before it can make that flip. It targets a precise, unchanging spot on the virus that stays the same across different RSV strains, so it works broadly. A built-in engineering tweak also makes the antibody stick around in the body for months instead of weeks, so one dose can protect an infant through an entire RSV season instead of needing repeated shots.
What it’s used for
Given to protect babies and young children from severe RSV lung infections — either their first RSV season after birth, or their second season if they're still considered high-risk.
- Mechanism
- RSV prefusion F protein antagonist (mAb)
- Drug class
- Monoclonal antibody
- Therapeutic area
- Infectious Disease