The effect of post-traumatic stress syndrome on the outcome of influenza vaccination

Psychological stress is known to affect immune function and to influence infectious disease susceptibility. Previous studies have demonstrated that chronic stress can impair humoral immune response to influenza vaccination but no data is available on post-traumatic stress disorder (PTSD). PTSD, according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), is a condition (or anxiety disorder) that can occur after exposure to extreme traumatic experience and is accompanied by intense fear, helplessness or horror. Exposure to trauma can result in immune deregulation, and increasing evidence suggests that there are immune alterations associated with PTSD. The aim of this study is to determine the effect of psychological stress on the immune response to influenza vaccination in war related PTSD patients (n=32). Samples were obtained before and 14 days after vaccination (Agrippal, Chiron, Italy) from patients and control subjects during 2003/2004 winter season. Inhibition of hemagglutination (IH) assay was used for detection of specific antiviral antibodies titre in sera for all viral strains contained in the vaccine. In addition, influenza-specific CD8+ T cells are determinated by MHC class I tetramer technology on a flow cytometer. The response to the vaccine was observed in ~80% of individuals after vaccination. Our results indicate that PTSD patients respond to the influenza vaccination similarly to healthy individuals.