Pre-exposure antibody prophylaxis protects macaques from severe influenza.

Summary

In a controlled nonhuman primate challenge, pre-exposure prophylaxis with the broadly neutralizing antibody MEDI8852 prevented severe disease and death after aerosolized H5N1 infection. Protection was dose-dependent and independent of Fc effector functions at the tested dose; ≥10 mg/kg recipients had negligible respiratory impairment compared to unprotected controls.

Key Findings

• Pre-exposure MEDI8852 protected cynomolgus macaques from severe disease and fatality after aerosolized H5N1 challenge.
• Protection was antibody dose-dependent; ≥10 mg/kg resulted in negligible respiratory impairment.
• At the tested dose, efficacy was independent of Fc-mediated effector functions.

Clinical Implications

Supports development of long-acting bnAb prophylaxis for high-risk exposures and stockpiling for pandemic response, with potential to protect healthcare workers and vulnerable populations.

Limitations

• Sample size not reported in the abstract and limited to a preclinical NHP model
• Pre-exposure prophylaxis may not translate directly to post-exposure treatment scenarios

Future Directions

Evaluate safety, pharmacokinetics, and efficacy of long-acting bnAb prophylaxis in humans; explore combination bnAbs and half-life–extended formats for broader and durable protection.