Efficacy of influenza vaccination in adult liver transplant recipients.

To assess the efficacy of influenza vaccination in immunocompromised adult liver transplant (LTx) recipients, the serum antibody responses of 61 of these patients and 35 liver cirrhosis patients with those of 45 of their healthy spouses were compared, after one and two vaccinations with a commercial trivalent subunit influenza vaccine. In addition, virus-specific proliferative T-cell responses were measured in LTx recipients and their healthy spouses. In all three study groups, significant rises in geometric mean antibody titers were observed for all three antigens after one vaccination. These titers did not continue to increase significantly after the second vaccination in patients with cirrhosis and control subjects but did rise for LTx recipients. The overall antibody response to all three influenza virus strains proved to be significantly lower in the LTx recipients than in the group of healthy subjects after both one and two vaccinations. More than 68% of the LTx recipients developed hemagglutination-inhibiting serum antibody titers >/=40 against all three vaccine strains after the first vaccination and more than 80% after the second vaccination. These findings correlated with the T-cell responses determined for the group of LTx recipients and healthy control individuals. Testing of the respective serum samples against influenza virus A/Sydney/5/97, which circulated in the 1997-1998 influenza season and showed a considerable mismatch with the vaccine strain A/Nanchang/933/95, indicated that such a mismatch may have significant consequences for vaccine efficacy, especially for LTx recipients. Collectively the data show that LTx recipients can be vaccinated effectively against influenza despite immunosuppressive therapy. A two-dose vaccination regimen improved vaccination efficacy in LTx recipients. Whether transplant patients generally benefit from a two-dose vaccination regimen should be evaluated further.