Fever after meningococcal B immunisation: A case series

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

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.

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 × 10⁹ /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.

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.