Emerging viruses in organ transplant recipients - immune responses to H1N1/09 influenza vaccine and Hepatitis E virus infection

Abstract

Solid organ transplant (SOT) recipients run the risk of serious infections. The pandemic influenza A H1N1/09 had unknown severity, so large-scale vaccination was needed. The AS03-adjuvanted vaccine (Pandemrix) had unknown effects among SOT recipients. We aimed to explore the influenza-antibody (ab) response, ab persistence 1 year later and response to the seasonal influenza vaccine (TIV/10) among adult SOT recipients. Reports of narcolepsy and possible allo-sensitisation following the H1N1/09 vaccination necessitated an analysis of HLA abs and further follow-up. 80% of SOT recipients and 100% of controls had seroprotective H1N1/09 titre levels after 2 vaccine doses (p=0.003). A significant loss of protection after 1 year was seen in all subjects. TIV/10 boosted a rise in seroprotection from 47% to 71% in the SOT group and 63% to 100% in controls. Non-responders were more often on triple immunosuppression and had lower renal function. No SOT recipient developed de novo HLA abs, but HLA abs with new specificities were detected in some patients. No acute rejection was seen within 2 years after vaccination. Two had chronic rejection within 1 year but a lower and mixed DSA response to the vaccine. The 4th study aimed to investigate the prevalence of hepatitis E (HEV) IgG, IgM and HEV infection, as chronic infection has been reported among SOT recipients. At transplantation, the anti-HEV IgG prevalence was significantly higher in SOT patients compared with blood donors, 30.6% and 16.8% respectively (p<0.0001). The patients appeared to have been infected at an earlier age. Two cases of de novo and 2 chronic HEV infection were suspected but could not be verified by HEV-RNA. To summarise, the AS03-adjuvanted H1N1/09 influenza vaccine was effective among SOT recipients but significantly less compared with controls. One third of all subjects lost their seroprotection after one year, but TIV/10 reproduced some of the former protection. No patient developed de novo HLA abs. The unexpected high prevalence of anti-HEV IgG among the Swedish SOT recipients highlights the possibility of hepatitis E as a new opportunistic infection in the immune compromised host.