Eculizumab inhibits the formation of terminal complement, which has a dramatic effect in preventing the symptoms and complications observed in PNH. Terminal complement is not required for combating most infective organisms but is needed to prevent Neisserial infection. Patients treated with eculizumab are therefore predisposed to developing infections from the Neisseria group of bacteria. The infection we are therefore most concerned about is that resulting in meningococcal sepsis or meningitis from the bacterium Neisseria meningitidis.

In order to reduce the risk of patients on eculizumab developing meningococcal sepsis all patients starting eculizumab are vaccinated with a quadravalent vaccine against the meningococcal strains A,C,W and Y. (A vaccine against serotype B, the commonest serotype observed in the UK, may soon be available.) Patients are also advised to take daily prophylactic antibiotics, either penicillin V 500mg bd or erythromycin 500mg bd. As well as this, all patients on eculizumab are given a patient safety card to carry with them which both advises them what to do if they become unwell and serves to alert physicians that they are at an increased risk of developing meningococcal infection.

Patients are also given emergency out-of-hours contact numbers for their PNH Centres if they become unwell. They should also have emergency numbers for their local haematology department.

If a patient with PNH is unwell and develops a temperature it is important that they are reviewed immediately by a healthcare professional. If meningococcal infection is suspected they should be commenced on either a third generation cephalosporin (if not neutropenic) or meropenem (if neutropenic). The PNH team who sees the patient should also be contacted urgently.