Fever after meningococcal B immunisation: A case series.

Aim: To document the clinical features and management of infants presenting with fever after their first meningococcal B vaccination and develop guidance for clinicians.

Methods: A prospective case series over 12 months was conducted in a tertiary paediatric hospital. Infants ≤3 months of age with fever who had received their first set of immunisations within the preceding 72 h were included.

Results: A total of 92 infants met the inclusion criteria, accounting for 0.78% of the local vaccinated population. The most commonly described associated features were poor feeding, sleepiness and irritability; 66 patients (72%) were admitted to hospital. Median C-reactive protein (CRP) was 12 mg/L, and median white cell count (WCC) was 16 × 10 /L. Fifteen patients (16%) had a lumbar puncture and were commenced on antibiotics. There was one confirmed bacterial infection in an infant who had presented with fever starting 54 h after immunisation. All other microbiology samples were negative. There were no cases of missed serious bacterial infection (SBI) in those patients who were observed or discharged.

Conclusions: The routine investigation of infants presenting with post-immunisation fever is not warranted if the infant appears otherwise well on examination. Where other common associated features are present or there is clinical concern, a period of observation is a prudent course of action. Paracetamol should be given peri-immunisation as per the national guidance. We suggest selective use of investigations, especially inflammatory markers, which are unlikely to discriminate between SBI and post-immunisation response. We advocate extra caution in infants presenting with fever more than 48 h after immunisation.