• immunisation
• infectious Diseases
• intensive Care
• neonatology

On 1 September 2015, the UK became the world’s first country to introduce a novel meningococcal B vaccine (Bexsero) into its national childhood immunisation programme. Bexsero is the only market authorised meningococcal B vaccine in the UK. Meningococcal B strains accounts for ~80% of all laboratory confirmed cases of invasive meningococcal disease (IMD) in England and Wales.1 Bexsero is estimated to protect against 73%–88% of the meningococcal B strains causing invasive disease in England and Wales.2

After observing more instances of clinical instability in our immunised neonates following the introduction of the new vaccine, we collected retrospective data to systematically compare tolerability of the vaccines in extremely premature babies (<28 weeks, <1200 g) before (Period 1, n=17, over 8 months) and following (Period 2, n=18, 8 months) the introduction of Bexsero in September 2015. Episodes of apnoea, desaturations, bradycardia and fever over 48 hours prior to vaccination and 48 hours following the vaccination were evaluated in each time period. We observed a general trend of increased incidence of apnoea, desaturations, fever and bradycardic episodes in Period 2 (figure 1). In Period 2, despite three doses of prophylactic paracetamol,3 28% (5/18) of babies had fever above 38°C.

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Figure 1

Complication postvaccination in both periods. CRP, C reactive protein; MenB, meningococcal B vaccine.

Before introduction of Bexsero, there were convincingly low levels of side effects in extremely premature babies following routine immunisation. After introduction of Bexsero, 33% (6/18) became unwell within 48 hours of vaccination and 28% (5/18) needed escalation in respiratory support. Eleven per cent (2/18) needed rescue ventilation following Bexsero vaccination. We also observed a more sustained C reactive protein response on unwell babies after Bexsero vaccination in Period 2, which influenced our decision to treat them with antibiotics for 5 days. Interestingly, the median gestational age of babies who became unwell (33%) following Bexsero administration was 25 weeks.

Since the cohorts in the two time periods are demographically matched and had near similar comorbidities, we are inclined to think that the clinical deterioration in Period 2 is due to the newly introduced MenB component. Following such events, we reported the adverse reactions through the yellow card scheme to inform the Medicines and Healthcare products Regulatory Agency.

Significant adverse effects4 challenge the confidence of parents in consenting for routine immunisation by healthcare professionals. Indeed, the worsening of clinical status after first experience with meningococcal B vaccination influenced parental decision-making with subsequent booster doses. Precautionary monitoring following Bexsero administration in premature babies is recommended. Larger prospective studies are needed to define more precisely the risks and benefits of the new immunisation programme for this highly vulnerable group.