What Is Vaccination?

A vaccine is a medicine that's given to help prevent a disease. Vaccines help the body produce antibodies. These antibodies protect against the disease. Vaccines not only help keep your child healthy, they help all children by stamping out serious childhood diseases.

Why do we need vaccines? What is immunization? What is immunity?

Vaccines are medications that boost our ability to combate off certain diseases. Many of the vaccine-preventable diseases are highly contagious and even fatal in unimmunized individuals (Table 1). Prior to the development of vaccines, these diseases disabled or killed millions of children. Many people living in developed countries today do not appreciate the value of vaccines because the successful use of vaccines has almost eradicated many of these diseases. These diseases are still dangerous and can kill people who are not adequately immunized.

Vaccines are medications that boost our ability to fight off certain diseases. Many of the vaccine-preventable diseases are highly contagious and even fatal in unimmunized individuals (Table 1). Prior to the development of vaccines, these diseases disabled or killed millions of children. Many people living in developed countries today do not appreciate the value of vaccines because the successful use of vaccines has almost eradicated many of these diseases. These diseases are still dangerous and can kill people who are not adequately immunized.

Vaccines are medications that boost our ability to fight off certain diseases. Many of the vaccine-preventable diseases are highly contagious and even fatal in unimmunized individuals (Table 1). Prior to the development of vaccines, these diseases disabled or killed millions of children. Many people living in developed countries today do not appreciate the value of vaccines because the successful use of vaccines has almost eradicated many of these diseases. These diseases are still dangerous and can kill people who are not adequately immunized.

How Do Vaccines Prevent Illness?

Vaccines trigger the body's immune responses to harmful viruses or bacteria so that the body can build up a resistance to that virus or bacteria. Learn more about how vaccines work to immunize people against illness.

What is dengue fever?

Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes. It is an acute illness of sudden onset that usually follows a benign course with headache, fever, exhaustion, severe joint and muscle pain, swollen glands (lymphadenopathy), and rash. The presence (the "dengue triad") of fever, rash, and headache (and other pains) is particularly characteristic of dengue. Dengue (pronounced DENG-gay) strikes people with low levels of immunity. Because it is caused by one of four serotypes of virus, it is possible to get dengue fever multiple times. However, an attack of dengue produces immunity for a lifetime to that particular serotype to which the patient was exposed. Dengue goes by other names, including "breakbone" or "dandy fever." Victims of dengue often have contortions due to the intense joint and muscle pain, hence the name breakbone fever. Slaves in the West Indies who contracted dengue were said to have dandy fever because of their postures and gait. Dengue hemorrhagic fever is a more severe form of the viral illness. Manifestations include headache, fever, rash, and evidence of hemorrhage in the body. Petechiae (small red or purple blisters under the skin), bleeding in the nose or gums, black stools, or easy bruising are all possible signs of hemorrhage. This form of dengue fever can be life-threatening or even fatal.

What areas are at high risk for contracting dengue fever?

Dengue is prevalent throughout the tropics and subtropics. Outbreaks have occurred in the Caribbean, including Puerto Rico, the U.S. Virgin Islands, Cuba, and Central America. Cases have also been imported via tourists returning from areas with widespread dengue, including Tahiti, the South Pacific, Southeast Asia, the West Indies, India, and the Middle East. Dengue fever is common and may be increasing in Southeast Asia. Thailand, Vietnam, Singapore, and Malaysia have all reported an increase in cases. According to the World Health Organization, there are an estimated 50 million cases of dengue fever with 500,000 cases of dengue hemorrhagic fever requiring hospitalization each year. Nearly 40% of the world's population lives in an area endemic with dengue.

How is dengue contracted?

The virus is contracted from the bite of a striped Aedes aegypti mosquito that has previously bitten an infected person. The mosquito flourishes during rainy seasons but can breed at water stagnant places. One mosquito bite can inflict the disease. The virus is not contagious and cannot be spread directly from person to person. There must be a person-to-mosquito-to-another-person pathway.