KNOW MORE ABOUT VACCINE

WHAT IS VACCINE ? WHAT IT CONTAINS ?AND HOW IT WORKS?

 

A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it, and to further recognize and destroy any of the microorganisms associated with that agent that it may encounter in the future.

In simple words, A vaccine is a type of medicine that trains the body’s immune system so that it can fight a disease it has not come into contact with before. Vaccines are designed to prevent disease, rather than treat a disease once you have caught it.

Vaccines contain the same germs that cause disease. (For example, measles vaccine contains measles virus, and Hib vaccine contains Hib bacteria.) But they have been either killed or weakened to the point that they don’t make you sick. Some vaccines contain only a part of the disease germ.

A vaccine stimulates your immune system to produce antibodies, exactly like it would if you were exposed to the disease. After getting vaccinated, you develop immunity to that disease, without having to get the disease first. This is what makes vaccines such powerful medicine. Unlike most medicines, which treat or cure diseases, vaccines prevent them.

VACCINE DEVELOPMENT 

Vaccines are made by taking viruses or bacteria and weakening them so that they can’t reproduce (or replicate) themselves very well or so that they can’t replicate at all. Children given vaccines are exposed to enough of the virus or bacteria to develop immunity, but not enough to make them sick. There are four ways that viruses and bacteria are weakened to make vaccines:

1. Change the virus blueprint (or genes) so that the virus replicates poorly. This is how the measles, mumps, rubella, and varicella vaccines are made. The virus blueprint is changed by a technique called cell culture adaptation [adapting a virus to grow in specialized cells grown in the lab instead of the cells it normally grows in]. Because viruses can still, to some extent, make copies of themselves after cell culture adaptation (and therefore are still alive), they are often referred to as live, attenuated (or weakened) viruses.

2.Destroy the virus blueprint (or genes) so that the virus can’t replicate at all. This is how the “killed” polio vaccine (or polio shot) is made. Vaccine virus is made by treating polio virus with the chemical formaldehyde. This treatment permanently destroys the polio genes so that the virus can no longer replicate.

3. Use only a part of the virus or bacteria. This is how the Hib, hepatitis B, and (in part) pertussis vaccines are made. Because the viral or bacterial genes are not present in the vaccine, the viruses or bacteria can’t replicate.

4. Take the toxin that is released from the bacteria, purify it, and kill it so it can’t do any harm. Some bacteria cause disease not by replicating but by manufacturing harmful proteins called toxins. For example, bacteria like diphtheria, tetanus, and pertussis (whooping cough) all cause disease by producing toxins. To make vaccines against these bacteria, toxins are purified and killed with chemicals (such as formaldehyde). Again, because bacterial genes are not part of the vaccine, bacteria can’t replicate.

VACCINE TESTING AND APPROVAL

Vaccines are tested before they’re recommended for use

Before a vaccine is ever recommended for use, it’s tested in labs. This process can take several years. FDA uses the information from these tests to decide whether to test the vaccine with people.

During a clinical trial, a vaccine is tested on people who volunteer to get vaccinated. Clinical trials start with 20 to 100 volunteers, but eventually include thousands of volunteers. These tests take several years and answer important questions like:

• Is the vaccine safe?
• What dose (amount) works best?
• How does the immune system react to it?

Throughout the process, FDA works closely with the company producing the vaccine to evaluate the vaccine’s safety and effectiveness. All safety concerns must be addressed before FDA licenses a vaccine.

Every batch of vaccines is tested for quality and safety

Once a vaccine is approved, it continues to be tested. The company that makes the vaccine tests batches to make sure the vaccine is:

1. Potent (It works like it’s supposed to)

2. Pure (Certain ingredients used during production have been removed)

Sterile (It doesn’t have any outside germs)

FDA reviews the results of these tests and inspects the factories where the vaccine is made. This helps make sure the vaccines meet standards for both quality and safety.

Vaccines are monitored after they’re recommended to the public

Once a vaccine is licensed and recommended for use, FDA, CDC, and other federal agencies continue to monitor its safety.