Question

Discuss role of vaccination in PNH patients who are to be started on complement inhibitor therapies.

Hint:

PNH patients on complement inhibitors must receive meningococcal, pneumococcal, and influenza vaccinations to reduce the risk of infections. Vaccination should be done before starting complement inhibition therapy.

Answer 1

Step 1: Risk of Infection in PNH.
PNH patients are at an increased risk of infections, particularly meningococcal infections, due to the inhibition of the complement system. Complement activation is crucial for the immune system’s defense against certain pathogens, including Neisseria species, which cause meningococcal infections. Inhibition of C5 with eculizumab or ravulizumab impairs this immune defense, increasing susceptibility to life-threatening infections.

Step 2: Vaccination Recommendations.
1. Meningococcal Vaccination: It is essential to vaccinate PNH patients against Neisseria meningitidis before initiating complement inhibitor therapy. Ideally, vaccination should be administered at least 2 weeks before starting eculizumab or ravulizumab to ensure sufficient immune response.
2. Pneumococcal and Haemophilus influenzae Vaccination: PNH patients should also receive vaccinations for Streptococcus pneumoniae and Haemophilus influenzae type B, as complement inhibition increases the risk of infections from these bacteria.
3. Annual Influenza Vaccination: PNH patients should be vaccinated annually against influenza to reduce the risk of respiratory infections, which could further compromise their health due to complement inhibition.

Step 3: Monitoring Post-Vaccination.
After vaccination, it is important to monitor for adequate immune response, particularly for meningococcal vaccines. In some cases, additional booster doses may be required.