Pandemic 2009 H1N1 influenza virus vaccination in lung transplant recipients: coverage, safety and clinical effectiveness in the Zurich cohort.

Background: Pandemic 2009 H1N1 influenza virus (H1N1) infection is considered harmful to lung transplant recipients (LTRs). Vaccination against this virus is recommended for LTRs, but little is known about associated benefits and risks. Our aim in this study is to document the safety and clinical effectiveness of the H1N1 vaccine in LTRs.

Methods: All LTRs received an informational letter on the H1N1 pandemic that included hygiene and vaccination recommendations. After completing a questionnaire, volunteering LTRs received Pandemrix (H1N1 2009 Monovalent AS03-Adjuvanted Vaccine; GSK). Adverse events (AEs) were documented at short-term follow-up visits and by telephone. Any flu-like symptoms were reported and a low threshold for performing nasal/pharyngeal swabs for virus detection was maintained.

Results: Of 168 eligible LTRs (107 already vaccinated for 2009 seasonal influenza), 148 (88%) received at least one vaccination with the H1N1 vaccine and 115 received a second dose. After the first vaccination, 44% had no AEs. Six self-limiting, severe AEs occurred, and the remainder were minor to moderate, predominantly injection-site reactions. After the second vaccination, AEs were clearly less frequent. All AEs resolved completely. Documented H1N1 infection occurred in 2 of 148 vaccinated LTRs, in contrast to 5 infections in 20 non-vaccinated LTRs.

Conclusions: H1N1 vaccination is generally well tolerated with mild to moderate, predominantly local AEs in most LTRs and few self-limiting severe events. Clinical effectiveness is good.