The "Why" Behind the Vax: A Patient's Guide to Complement Inhibitors and Meningitis Risk

Living with myasthenia gravis (MG) means learning about many different treatments. Some treatments are new and work in different ways. One newer class of drugs is called complement inhibitors. These drugs can be very helpful for managing MG symptoms.^1,2

However, these drugs also come with a very specific and serious risk. This risk is why your doctor will tell you that you must get a specific vaccine called the meningococcal vaccine. This vaccine is for meningococcal meningitis. It can be confusing to hear that a drug for muscle weakness is linked to meningitis. Let’s break down why this is.³

A primer on the complement system

Your immune system’s job is to find and destroy germs. The complement system is 1 part of your immune system.³

Think of it as your body's security team. It is made of special proteins in your blood. When this system "activates," it marks germs for destruction. It helps clear bacteria and other threats from your body. This is a normal and healthy process.3

How does this impact myasthenia gravis?

Myasthenia gravis is an autoimmune disease. This means the immune system does not work as it should. It attacks your body's own healthy cells.¹

In MG, the immune system attacks the connection between your nerves and muscles. The complement system is a key part of this mistaken attack. It gets activated when it should not. These activated proteins damage the nerve-muscle connection. This damage stops nerve signals from reaching the muscles properly. This leads to the muscle weakness that people with MG experience.¹

How do complement inhibitors work?

Complement inhibitors are drugs designed to stop this mistaken attack. They work by "inhibiting," or blocking, the complement system.^2,3

By blocking these proteins, the drugs stop the immune system from damaging the nerve-muscle connection. This action can help reduce muscle weakness. It may improve MG symptoms for many people. Examples of these drugs include:^2-4

• Eculizumab (Soliris®)
• Ravulizumab (Ultomiris®)

What is the risk of using these drugs?

The complement system has an important job. It is very good at fighting certain types of bacteria. When complement inhibitors block this system, that protection is lowered.^3-5

This leaves your body open to specific infections. The most serious risk is meningococcal infection. This infection is caused by bacteria called Neisseria meningitidis.^3-5

This risk is so serious that these drugs have a boxed warning from the U.S. Food and Drug Administration (FDA). This is the strictest warning the FDA uses. It alerts doctors and patients that people taking these drugs have a much higher risk of life-threatening meningococcal infections.^4,5

What is meningococcal disease?

Meningococcal disease is rare but very dangerous. The bacteria can cause 2 serious conditions:⁵

• Meningitis – swelling of the protective lining around the brain and spinal cord
• Septicemia – a serious blood infection

These infections can happen very fast. They can be deadly if not treated right away. Because complement inhibitors weaken your body's main defense against these bacteria, your risk is much higher than average.⁵

Why is the vaccine required for MG patients?

This brings us to the vaccine. Vaccines work by training your immune system to recognize and fight specific germs. The meningococcal vaccine trains your body to fight the Neisseria meningitidis bacteria.^2,3,5

Because the complement inhibitor drug turns off your natural defense, the vaccine is needed to build a new defense. It gives your body another way to protect itself.^2,3,5

The FDA and the Centers for Disease Control and Prevention (CDC) have clear rules for this:^3,5

You must get the meningococcal vaccine at least 2 weeks before your first dose of the complement inhibitor. This 2-week period gives the vaccine time to start working. If your treatment must start right away, you will get the vaccine with your first dose.

You will also need booster shots to stay protected. Your doctor will tell you the schedule.^3,5

You still need to watch for symptoms

Your doctor will talk to you about these risks. You will be given a special Patient Safety Card. You must carry this card with you at all times. This card tells any healthcare worker that you take a complement inhibitor and are at high risk for this infection.⁵

Even with the vaccine, the risk is not 0 percent. You must still watch for symptoms of meningitis. Get medical help right away if you have:^3-5

• Sudden high fever
• A bad headache
• Stiff neck
• Nausea or vomiting
• Confusion
• Eyes being sensitive to light

The vaccine is a necessary step for safety

Complement inhibitors are important drugs that can help many people with MG. They work by quieting a part of the immune system. But this action creates a serious risk of meningococcal infection.^2,3

Getting the vaccine is a required safety step. It helps protect you from this dangerous side effect. Always talk to your doctor about the risks and benefits of your treatment plan.³