Delayed diagnosis of novel H1N1 influenza pneumonitis in a vaccinated heart transplant recipient

Abstract

We report the case of a 36-year-old heart transplant recipient who presented with pyrexia, respiratory failure, and progressive chest X-ray infiltrates 74 days after orthotopic heart transplantation. Notably, this patient had been vaccinated against both seasonal and novel 2009 H1N1 influenza viruses. Nasopharyngeal aspirates tested negative for influenza viruses. Diagnosis of novel H1N1 influenza pneumonitis was made on a bronchiolar lavage sample 14 days after initial presentation. Treatment was successful with high-dose oseltamivir. Novel H1N1 influenza infection has been reported in vaccinated lung transplant candidates and recipients, although compliance with vaccination of only 20% was found in infected patients. With this report, we present a case of novel H1N1 influenza vaccine failure in a fully vaccinated heart transplant recipient. The efficacy of this vaccine in heart transplant recipients is unknown. Studies on seasonal influenza vaccination in heart transplant recipients suggest a diminished antibody response. Given the rapid spread of novel H1N1 influenza virus, transplant recipients may begin vaccination as soon as 1 month after transplantation. However, this case illustrates how the immune response to early vaccination may only be partially protective in heart transplant recipients and that assumed vaccine-afforded protection may result in a delayed diagnosis. (Table 1). The immunosuppressive regimen used in solid-organ transplant recipients may also contribute to the risk of vaccine failure. For example, mycophenolate mofetil (used in this patient) is associated with a lower serologic response to vaccination than other immunosuppressive drugs. Furthermore, in addition to chemotherapy and bone marrow transplantation for acute myeloid leukemia 5 years before heart transplantation, this patient’s medical history also included heparin-induced thrombocytopenia. This therefore suggests a previous history of immune dysfunction, which may also have contributed to vaccine failure. European surveillance data has reported cases of novel H1N1 influenza pneumonitis in vaccinated (non-immunocompromised) patients during this pandemic, indicating that immunosuppression alone may not account for vaccine failure.