Clesrovimab: a new monoclonal antibody in the dm+d
The NHS Business Services Authority has added clesrovimab to the dm+d dictionary (version 6.1.0). This is a monoclonal antibody that targets the respiratory syncytial virus (RSV) F protein and is used for passive immunisation in high-risk infants during RSV season.
What is clesrovimab used for?
Clesrovimab provides season-long protection against RSV disease in vulnerable infants. It is administered as a single intramuscular injection at a dose of 50 mg/kg, typically given in autumn or winter before the peak RSV season. This passive immunisation approach is particularly valuable for infants at high risk of severe RSV infection, such as those born prematurely or with chronic lung disease.
Event medicine relevance
Clesrovimab is not typically administered at medical events. It is a preventive agent given in primary care or hospital settings before RSV season begins. Event responders are unlikely to administer this drug during their shifts. However, you may encounter an infant who has recently received clesrovimab and presents with signs of an adverse reaction. If a child shows signs of anaphylaxis or severe hypersensitivity reaction following recent injection, treat according to your anaphylaxis protocol and escalate urgently. Always confirm the injection history with parents or carers.
Key cautions and interactions
- Bleeding risk: Avoid IM injection in infants with thrombocytopenia or bleeding disorders.
- Live vaccines: Live attenuated vaccines should be deferred for at least 3 months after clesrovimab administration.
- Inactivated vaccines: These may be given concurrently at different injection sites.
- Acute illness: Consider deferral if the infant has fever or acute illness at the time of scheduled injection.
- Immunocompromised infants: Efficacy may be reduced; clinical assessment is needed.
Monitoring after injection
Standard post-injection observation includes monitoring vital signs (temperature, respiratory rate, oxygen saturation) and observing for signs of hypersensitivity for 15–30 minutes. Any fever or respiratory symptoms that develop despite prophylaxis warrant clinical review.