1. Sipavibart, an investigational monoclonal antibody, reduced symptomatic COVID-19 cases by 34.9% in non-Phe456Leu-containing variants.
2. Sipavibart was ineffective against resistant SARS-CoV-2 variants dominated by Phe456Leu-containing variants.
3. Adverse events with sipavibart were comparable to the comparator group, with no serious cardiovascular or thrombotic events linked to sipavibart.
4. Developing monoclonal antibodies remains challenging due to the rapid evolution of SARS-CoV-2 variants.
5. Alternative preventive measures, such as immunobridging strategies, may be necessary to address the evolving landscape of COVID-19 prophylaxis for immunocompromised patients.

Source: The Lancet