Publication:

A preventable severe influenza A pneumonia after rituximab therapy for pemphigus vulgaris: a case report highlighting the critical role of vaccination

Rituximab is an effective first-line therapy for pemphigus vulgaris (PV) but causes prolonged B-cell depletion, increasing susceptibility to infections. We report a 38-year-old man with PV who developed severe influenza A (H3) pneumonia 20 days after his second rituximab infusion, having declined influenza vaccination. Prior to rituximab, he received corticosteroids and azathioprine, but lesions persisted. Upon presentation, he experienced headache, myalgia, arthralgia, and fatigue. Laboratory tests revealed lymphopenia and elevated C-reactive protein, and a respiratory viral panel confirmed influenza A H3. Imaging showed bilateral basal infiltrates with ground-glass opacities. The patient required hospitalization, antiviral therapy with oseltamivir, antibiotics, and supplemental oxygen. He recovered without intensive care admission. This case highlights the critical importance of influenza vaccination before rituximab therapy. Vaccination should not be left to patient discretion, and rituximab should never be administered without prior immunization, especially during winter months, to prevent severe or potentially fatal influenza complications.