The 4-component meningococcal serogroup B vaccine 4CMenB (Bexsero) is the first 
vaccine against this serogroup and has been approved by licensing authorities in 
Europe, Canada and Australia. Therefore, the vaccine may enter soon nationwide 
vaccine recommendation schemes. We report on a case of a 5-month-old infant who 
developed prolonged upper extremity dysfunction after the second injection of 
the 4CMenB vaccine in the left deltoid muscle and was concomitantly applied with 
2 routine vaccinations. Myositis, periostitis, (peri-) vasculitis and axillary 
inflammation were confirmed by magnetic resonance imaging. Two months after 
initial initiation of an anti-inflammatory and an antibiotic treatment, symptoms 
completely resolved. Administration of 3 vaccines requires clear recommendations 
for the preferred injection site in infants because increased reactogenicity of 
4CMenB may lead to local severe adverse events.