This study aims to assess the risk of solid organ transplant (SOT) rejection following vaccination with Pandemrix™ and/ or seasonal influenza vaccination.

Data on the safety of pandemic H1N1 vaccination in transplanted patients is relatively limited; to date, although some studies showed transient increases in alloreactivity, there is no evidence that H1N1 vaccines caused clinical rejection or organ dysfunction. In addition, studies have shown that influenza infection is a known independent risk factors for rejection. Considering that transplant recipients are a target population for immunisation with future pandemic vaccines, it is important to investigate the risk of rejection following vaccination in this patient population.

Using the self-controlled case series design that allows to control implicitly for potential confounding factors, this study aims at investigating the risk of solid organ transplant rejection (liver, kidney, lung, heart, pancreas) following vaccination with Pandemrix™ in the United Kingdom Clinical Practice Research Datalink GP Online Database (CPRD GOLD). Data from the Hospital Episodes Statistics database will also be used. The effect of seasonal influenza vaccination and of various infections including influenza H1N1 will also be explored.

Inclusion Criteria:

• Subject defined as acceptable in the CPRD GOLD.
• Subject with at least one solid organ transplant rejection reported in the CPRD GOLD and/or HES during the overall study periods (01 September 2006 to 31 October 2010).

Exclusion Criteria:

• Subject from HES matched to more than one subject in the CPRD GOLD.

Subject defined as acceptable in the CPRD GOLD with at least one solid organ transplant rejection reported during the overall study periods (01 September 2006 to 31 October 2010).