What Are Vaccines and Immunizations?

Vaccines help protect people from diseases that can cause serious illness, disability, or death. They prepare the immune system to recognize a specific germ before a person encounters the actual infection. This preparation can lower the risk of becoming sick and may reduce the severity of an illness if infection still occurs. People often use the words vaccine, vaccination, immunization, and shot as though they mean the same thing. The terms relate to one another, but each describes a different part of the disease prevention process. If you have questions about vaccines or which ones you may need, read on to learn more.

What is a vaccine?

A vaccine is a medical product that teaches the immune system how to respond to a particular disease. Depending on the vaccine, it may contain a weakened or inactive germ, a harmless part of a germ, genetic instructions, or another substance that triggers an immune response. The vaccine does not need to cause the full disease to train the body. Instead, it gives the immune system enough information to produce a defense. The body may create antibodies and specialized immune cells that remember the germ. If exposure occurs later, the immune system can respond faster.

What does immunization mean?

Immunization describes the process of gaining protection against a disease. Vaccination often starts that process, but the two words do not mean the same thing. A vaccine is the product, vaccination is the act of receiving it, and immunization is the protection that develops afterward.

What does a shot mean?

A shot simply describes one way to deliver a substance with a needle. Many vaccines come as injections, but not every shot contains a vaccine and not every vaccine comes in a shot. Doctors also give medicines such as insulin and certain antibiotics through injections. Some vaccines come as nasal sprays or oral medicines instead.

Why are vaccines important?

Vaccines protect individuals, but their effects can reach beyond the person who receives them. When fewer people become infected, diseases have fewer opportunities to spread. This can help protect infants, people with weakened immune systems, and others who cannot receive certain vaccines. Over the years, vaccination programs have sharply reduced many dangerous diseases around the world. The World Health Organization reports that vaccines now prevent more than 30 serious diseases and infections. It also estimates that immunization prevents millions of deaths each year.

Are vaccines tested for safety?

Vaccines go through laboratory research and clinical testing before they receive approval for use in the United States. The Food and Drug Administration reviews information about safety, effectiveness, quality, purity, and strength. Health agencies continue to monitor vaccines after approval so they can investigate possible side effects and new safety concerns.

What should you do?

Vaccines and immunizations remain an important part of preventive healthcare throughout life. Some childhood vaccines provide long-lasting protection, while other vaccines require later doses or periodic updates. Age, health conditions, pregnancy, work, and travel plans can all affect which vaccines a person needs. Talk with your healthcare provider if you are unsure whether your vaccinations remain current. They can review your records, answer questions, and recommend vaccines based on your health and individual risks.

Related Article: What Happens During Vaccines?