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 Understanding Vaccines

·         The History of Vaccines

·         What are vaccines?

·         Why are vaccines given?

·         How do vaccines work?

·         How are vaccines administered?

·         Risks to vaccination

·         The future of  vaccine research

History of Vaccines

Dr. Edward Jenner, a physician from England changed the world of vaccines when he developed the first vaccine for the prevention of smallpox disease.  In 1796, England was faced with an epidemic of smallpox outbreaks that killed 40% of the people that came in contact with the fatal disease and left its survivors with disfiguring scars. Dr. Jenner observed that milkmaids who had been infected with cowpox – a disease similar to smallpox, but found in cows - were protected from smallpox. Dr. Jenner got fluid from a milkmaid who had been infected with cowpox and injected it into the skin of a young healthy boy who had never been sick with smallpox. Six weeks later, the young boy was exposed to smallpox and remained free of smallpox disease. This experiment was the hallmark of vaccine development which would help to prevent and eradicate many communicable diseases that impact the world today.

Based on this experiment, Dr. Jenner coined the term vaccination from the Latin words vacca (Cow) and vaccinia (cowpox).

To learn more about Dr. Edward Jenner’s smallpox vaccine development click here.

What are Vaccines?

Vaccines are biological agents that stimulate an immune response in the body. They are made from antigens which are substances that the body recognizes as foreign. This weakened form of a disease-causing germ prepares the body to fight infections in the future.

 An effective vaccine causes the immune system to produce antibodies, but should not cause signs or symptoms of the disease.

Why are Vaccines Given?

Vaccines help prevent disease and save lives.  They have helped to eradicate diseases like smallpox and decrease the morbidity and mortality rate in areas with high levels of disease. Vaccines can help to protect those who come into contact with sick people.

Disease prevention is the key to public health. The goal of the Center for Immunization Research (CIR) at the Johns Hopkins Bloomberg School of Public is to develop vaccines to prevent and eradicate infectious diseases across the globe. It is always better to prevent a disease than to treat it. Infectious diseases are now the world's biggest killer of children and young adults. They account for more than 13 million deaths a year - one in two deaths in developing countries. Most deaths from infectious diseases occur in developing countries - the countries with the least money to spend on health care (WHO). 

How do Vaccines Work?

Vaccines work by boosting the body’s own immune system , helping it to produce antibodies that fight disease-causing germs. The body can make antibodies when exposed to the disease or after getting a vaccine.

To learn more about how the immune system works click here

How are Vaccines Administered?

Vaccines are given in several ways:

Are There Risks to Getting Vaccinated?

Because vaccines are made from weakened disease-causing germs, they are usually safe. However, there may be risks associated with the vaccine that are unknown. Side effects can occur with any medicine, including vaccines.  Depending on the vaccine, and how it is given, the side effects can include: slight fever, rash, or soreness at the site of injection, runny nose, headache, sore throat and cough. A health care provider can give more information about specific risks and side effects of the vaccine.

The Future of Vaccine Research

The National Institutes of Health (NIH), World Health Organization (WHO), pharmaceutical and vaccine research centers like the CIR are working hard to develop vaccines to prevent and control infectious diseases. The CIR is a world leader in vaccine research and education. As recently as August 2009, the CIR worked with CSL, an Australian pharmaceutical company, to conduct clinical trials for the H1N1 influenza vaccine.  

Here at the CIR we are studying ways to develop vaccines for global diseases such as dengue fever, Traveler’s diarrhea and respiratory viruses. The development of these vaccines will help to prevent and improve the lives of millions of people around the world.  The CIR offers both inpatient and outpatient vaccine studies. For more information about the CIR’s published study results click here.

To learn more about participating in a vaccine clinical trial, visit our ENROLL now page or you may contact us at (410-955-7283) or toll free (877-863-1374).

To learn more about vaccines and vaccine safety, please visit the Centers for Disease Control website at