Complement inhibitors are moving from paroxysmal nocturnal haemoglobinuria and atypical haemolytic uraemic syndrome into glomerular disease, and the meningococcal risk travels with them. Blocking C3 or C5 removes the terminal pathway that handles encapsulated organisms, and invasive meningococcal disease in a patient on a complement inhibitor can be fulminant.
So vaccinate at least two weeks before the first dose where the clinical situation allows it. Cover serogroups A, C, W and Y and serogroup B separately — the two vaccines are not interchangeable and both are needed. Where treatment cannot wait two weeks, vaccinate and give antibiotic prophylaxis to cover the gap.
Then make sure the patient can act on it. Give them a card stating they are on a complement inhibitor, tell them that any fever needs assessment the same day rather than the next morning, and write the vaccination dates and booster schedule somewhere the next clinician will find them. The failure mode is a febrile patient assessed by someone who does not know what they are taking.
- Give meningococcal ACWY and B vaccines at least two weeks before the first dose of a complement inhibitor.
- Add antibiotic prophylaxis where treatment cannot be delayed for the vaccine to take effect.
- Issue a patient alert card and confirm the patient can explain what it means.
- Tell the patient that any fever requires same-day assessment, not a wait-and-see.
- Record vaccination dates and the booster interval in the notes; protection wanes and treatment continues.
Why it matters
The patient most at risk from meningococcal disease is the one whose treating clinician does not know they are complement-blocked.
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