The Effects of Influenza Vaccination on Immune Function in Patients with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis

Immune dysfunction is a hallmark of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME). The purpose of this pilot study was to identify the effects of influenza vaccination on immune function in patients with CFS/ME. We included 7 patients meeting the Centre for Disease Control and Prevention criteria (CDC 1994) for ME/CFS and 8 control subjects. Bloods were collected from all participants prior to vaccination with Influvac, a trivalent inactivated influenza vaccine (TIV), 14 and 28 days following vaccination. The immune parameters examined include Natural Killer (NK) phenotypes, NK cytotoxic activity, FOXP3 and Th1/Th2/Th17 related cytokines. Flow cytometric protocols were employed. There was no significant difference in NK phenotypes and Tregs numbers between CFS/ME patients and healthy controls. However, NK activity was significantly decreased at baseline and at 28 days, while at 14 days it significantly increased in the CFS/ME patients compared to the healthy controls. Th1 pro-inflammatory cytokines increased considerably in the CFS/ME patients at 28 days compared to the non-fatigued controls. Only one Th2 cytokine, IL-4, increased in the CFS/ME participants. FOXP3 expressing Tregs only increased significantly at day 28 post vaccination in the CFS/ME patients compared to the healthy controls. Self-rated wellbeing was lower for patients at day 28 while at baseline and day 14 no differences were observed. In this pilot study immunization with influenza vaccine is accompanied by a degree of immune dysregulation in CFS/ME patients compared with controls. While vaccination may protect CFS/ME patients against influenza, it has the ability to increase cytotoxic activity and pro-inflammatory reactions post vaccination. The role of Tregs in promoting a toxic effect at 28 days post-vaccination in our patient group cannot be ruled out. The benefits of influenza vaccine still likely outweigh the risks CFS/ME patients experience following vaccination.