The effect of exercise on local and systemic adverse reactions after vaccinations – Outcomes of two randomized controlled trials

Abstract Introduction An adverse reaction associated with vaccination is considered to be a key barrier to vaccinate, yet little attention has been given to interventions to reduce their occurrence. Exercise is a behavioural adjuvant which may also influence adverse reactions. Here, two randomized controlled trials are reported, examining the effects of exercise on self-reported adverse reactions following vaccination in adolescents and young adults. Methods Study one ; 116 adolescents receiving the HPV vaccine were randomly allocated to either Control (n = 56) or Pre-vaccine Exercise (n = 60) group (2015–2016). Exercise consisted of 15-minutes upper body exercise. Study two ; 78 young adults receiving the influenza vaccine were randomly allocated to either Control (n = 19), or one of 3 exercise groups: Pre-vaccine Arm (n = 19), Pre-vaccine Leg (n = 20) or Post-vaccine Arm (n = 20) (2017). Exercise included 15-minutes of arm or leg exercises prior to or after vaccination. All participants in both studies completed an adverse events diary for seven-days post-vaccination. Results Study one ; Reported days of tenderness in female adolescents that exercised were significantly lower than control ( p  = 0.032), with a similar trend in reported days of pain ( p  = 0.050). Furthermore, days of feeling ill ( p  = 0.070) and reduced appetite ( p  = 0.067) were found to be lower with exercise, although not significant. Overall, female adolescents reported significantly more days of pain ( p  = 0.003), tenderness ( p p  = 0.011), and feeling ill ( p  = 0.0040). Study two ; Exercise groups reported reduced days of swelling ( p  = 0.018), fever ( p  = 0.013), and lowered appetite ( p  = 0.011) across both genders. Furthermore, females reported reduced days of medication use with exercise ( p  = 0.034), and a trend toward reduced days of swelling ( p  = 0.052). Discussion In two separate trials, a short bout of exercise reduced reported adverse reactions after vaccinations for local and systemic adverse reactions. Gender differences in reported local and systemic adverse reactions were more evident among adolescents than young adults. These findings support the need for further work to examine the potential benefit of exercise in improving vaccination procedures.