Psychosocial factors are associated with the antibody response to both thymus-dependent and thymus-independent vaccines

The present study examined the association between psychological stress, social support and antibody response to both thymus-dependent and thymus-independent vaccinations. Stressful life events in the previous year and customary social support were measured by standard questionnaires at baseline in 75 (41 females) healthy students. Antibody status was assessed at baseline, 4 and 18 weeks following vaccination with formaldehyde inactivated hepatitis A virus and pneumococcal polysaccharides, which induce thymus-dependent and -independent antibody responses respectively. Controlling for baseline antibody status, life event stress was negatively associated with antibody response to the hepatitis A vaccine at the 18-week follow-up; participants reporting a greater number of stressful life events had a poorer antibody response. There was no relationship between psychological stress and antibody response to pneumococcal vaccination. Social support was not associated with the antibody response to hepatitis A vaccination. However, there was a significant association between support and the antibody response to the thymus-independent pneumococcal vaccine at 4-week followup; participants with larger social networks mounted a better response. These relationships could not be accounted for by age and sex, or by variations in health behaviours. Psychosocial factors would appear to influence the response to both thymusdependent and thymus-independent vaccines, but not in the same manner.