Vaccines

Third participant enrolled in VRC 207 receives a dose of the investigational NIAID/GSK Ebola vaccine
Credit: NIAID

A 26-year-old man, the third participant enrolled in VRC 207, receives a dose of the investigational NIAID/GSK Ebola vaccine at the NIH Clinical Center in Bethesda, MD.

Vaccines take advantage of your body’s natural ability to learn how to combat many disease-causing germs, or microbes, that attack it. Vaccines provide safe, cost-effective, and efficient means of preventing illness, disability, and death from infectious diseases.

Why Is Vaccine Research a Priority for NIAID?

Once your immune system is trained to resist a disease, you are said to be immune to it. Before vaccines, the only way to become immune to a disease was to actually get it and, with luck, survive it. This is called naturally acquired immunity. Vaccines, which provide artificially acquired immunity, are an easier and less risky way for a body to develop immunity to many diseases. Vaccines can prevent a disease from occurring in the first place, rather than attempt to cure it after the fact. Learn more about the benefits of vaccines and vaccine research.

How Is NIAID Addressing This Important Area of Study?

NIAID conducts and supports basic research in areas such as infectious diseases, microbiology, and immunology to generate the knowledge essential for developing safe and effective vaccines. NIAID also supports clinical research on vaccines against bacterial, viral, and parasitic microbes in people of all ages and risk categories. Vaccine safety is an integral component of all NIAID vaccine research and development. Read more about the NIAID role in vaccine research.

What Is a Vaccine?

Chances are you never had diphtheria. You probably don’t know anyone who has suffered from this disease, either. In fact, you may not know what diphtheria is. Similarly, diseases like whooping cough (pertussis), measles, mumps, and German measles (rubella) may be unfamiliar to you. In the 19th and early 20th centuries, these illnesses struck hundreds of thousands of people in the United States each year, mostly children, and tens of thousands of people died. The names of these diseases were frightening household words. Today, they are all but forgotten. That change happened largely because of vaccines.

How Vaccines Work

The human immune system is a complex network of cells and organs that evolved to fight off infectious microbes. Vaccines teach the immune system by mimicking a natural infection. Vaccines contain a weakened form of a virus that doesn’t cause disease or reproduce very well. The immune system can’t tell that the vaccine viruses are weakened, so they engulf the viruses as if they were dangerous.

Types of Vaccines

Scientists take many approaches to designing vaccines against a microbe. These choices are typically based on fundamental information about the microbe, such as how it infects cells and how the immune system responds to it, as well as practical considerations, such as regions of the world where the vaccine would be used.

Vaccine Adjuvants

A vaccine adjuvant is a substance that is formulated as part of a vaccine to enhance its ability to induce protection against infection. Adjuvants help activate the immune system, allowing the antigens—pathogen components that elicit an immune response—in vaccines to stimulate a response that leads to long-term protection.

Making Safe Vaccines

Each person’s immune system works differently, so occasionally a person will not respond to a vaccine. Very rarely, a person may have a serious adverse reaction to a vaccine, such as an allergic reaction that causes hives or difficulty breathing. But serious reactions are reported so infrequently—about once every 100,000 vaccinations—that they can be difficult to detect and confirm. More commonly, people will experience temporary side effects, such as fever, soreness, or redness at the injection site. These side effects are, of course, preferable to getting the illness. 

Vaccines of the Future

Vaccines delivered through a needle must be kept sterile, which is difficult in some settings. Also, injections usually must be administered by trained personnel, and injecting many people quickly—as would be necessary in case of a widespread outbreak—is not easy. For these reasons, scientists are investigating new ways to deliver vaccines.

Content last reviewed on July 11, 2016