Influenza vaccines in the setting of solid-organ transplantation: Are they safe?

Purpose of Review: Influenza is a major cause of morbidity and sometimes mortality in immunocompromised patients, including solid-organ transplant (SOT) recipients. Current guidelines call for influenza immunization of SOT recipients from 3 months posttransplant onward; the stated reason for delaying immunization in the early posttransplant period is an efficacy rather than a safety issue. Despite concerns about possible rejection raised in small case series and studies of alloimmune responses in immunized patients, virtually all larger clinical studies have shown no increased risk of rejection or allograft dysfunction after influenza vaccination. Recent Findings: Further evidence, mostly supporting the safety of influenza vaccine, has been published during the past 2 years. For example, one study using a large database of 51 730 adult Medicare primary renal transplant recipients showed that influenza vaccination was actually associated with a lower risk of graft loss and death. It appears that actual influenza infection itself, rather than the vaccine, carries a risk of allograft dysfunction. Summary: At this time, influenza vaccine after SOT is considered clinically safe, and current evidence supports the guidelines' recommendations to immunize. The issue of optimal timing for efficacy still remains to be resolved. In addition, educational tools for increasing the acceptance of influenza vaccine in healthcare workers and family members are described.