Study Background and Disease Burden
Respiratory syncytial virus (RSV) remains a significant cause of severe respiratory illness, particularly in the immunocompromised population. Among these, allogeneic hematopoietic cell transplant (alloHCT) and lung transplant (LT) recipients bear the highest burden of morbidity and mortality associated with RSV infection. Viral clearance and immune defense are compromised due to immunosuppressive therapy and altered immune reconstitution in these patients, leading to increased susceptibility compared to other immunocompromised groups. Despite the urgent need, these high-risk populations have been routinely excluded from pivotal clinical trials investigating RSV vaccines, leaving clinicians with limited direct evidence of efficacy and safety for this subset. The advent of adjuvanted vaccines, such as the RSVPreF3 formulation designed to elicit both humoral and cellular immunity, offers promise for protection but requires rigorous evaluation in transplant recipients to define safety profiles and immunogenic potential.
