Question

How do vaccines provide immunity against a disease?

Answer 1

A vaccine is a biological preparation that induces active acquired immunity against a specific infectious disease. A vaccine usually contains an agent that looks like a disease-causing microorganism and is often made from weakened or killed versions of the microbe, its toxins, or one of its surface proteins.

Complete answer:
When disease germs enter your body, they begin to multiply. Your immune system recognises these germs as foreign invaders and responds by producing antibodies, which are proteins. The first job of these antibodies is to help destroy the germs that are making you sick. Antibodies may not act quickly enough to keep you from getting sick, but by eliminating the attacking germs, they aid in your recovery.

The second function of antibodies is to protect you from future infections. They remain in your bloodstream and will defend you if the same germs try to infect you again, even after many years. Only now, as they have gained experience in combating these specific germs, will they be able to destroy them before they cause you harm. This is the definition of immunity. This is why most people only get diseases like measles or chickenpox once, despite being exposed many times throughout their lives.

Vaccines provide a solution to this issue. They aid in the development of immunity without the need for you to become ill first. Vaccines are made from the same germs or sections of them that cause disease; the polio vaccine, for example, is made from the poliovirus. However, the germs in vaccines are either killed or weakened so that they do not cause illness.

Vaccines containing these weakened or killed germs are administered to you via injection. Your immune system reacts to the vaccine in the same way that it would if it were infected with the disease by producing antibodies. Vaccine germs are destroyed by antibodies in the same way that disease germs are destroyed in a training exercise. They then remain in your body, providing immunity. The antibodies are there to protect you if you are ever exposed to the real disease.

Note: Vaccination Types
i) Active immunisation occurs when the body generates its own response to an infection via specialised cells and antibodies stimulated by vaccines. Full protection takes time to develop, but it lasts a long time.
ii) Passive immunisation entails passing ready-made antibodies directly to the person being immunised. Although this provides immediate protection, passive immunisation may only last a few weeks or months. Antibodies are passed from mothers to infants via the placenta and breast milk, protecting the infants for a short period of time after birth.