Tetanus is a disease that affects neuromuscular function. The bacteria that cause tetanus produce a toxin that enters the spinal cord and blocks the release of the inhibitory neurotransmitter GABA. People who are risk of developing tetanus can be treated with tetanus toxoid and tetanus antitoxin. Tetanus toxoid is a vaccine  and tetanus antitoxin contains antibodies against the toxin produced by the bacteria. Why would tetanus toxoid and antitoxin be used together to treat people at risk of developing tetanus? How would their effects differ? Why are boosters of tetanus toxoid required?

Because the tetanus toxin blocks the release of the inhibitory neurotransmitter GABA it enables uncontrolled muscle contraction to occur. The uncontrolled muscle contraction is characteristic of tetanus and is the origin of its old name of "lockjaw". If an unvaccinated person is treated with tetanus toxoid their acquired immune system will be stimulated to produce an immune response. However, the initial immune response will be quite slow, and by the time it has a strong protective effect the tetanus bacteria may have produced enough toxin to kill the patient. The antitoxin contains antibodies which bind to the toxin and prevent it from having its effect. The antitoxin can therefore provide protection in people who have not been vaccinated. Over time, immune memory can fade and that is why booster vaccinations are required for many diseases.