The immune response protects the body against disease. Infants are born with a natural (inborn) immunity against disease (the result of antibodies transmitted from the mother to the unborn child through the placenta and to infants through breast milk). However, this immunity is temporary, lasting only through early infancy.

Immunization (vaccination) is a means of triggering acquired immunity. This is a specialized form of immunity that provides long-lasting protection against specific antigens, such as certain diseases. Small doses of an antigen (such as dead or weakened live viruses) are given to activate immune system "memory" (specialized white blood cells that are capable of "recognizing" the antigen and quickly responding to its presence). The immune system thereby learns how to attack and defend the body against specific diseases using weakened opponents. Memory then allows the body to react quickly and efficiently when faced with the actual disease (the body has acquired "resistance" to the disorder). Immunization is one of the best means to protect against many contagious diseases (those that can be passed from person to person). Indeed, smallpox was actually wiped off the planet through an aggressive, international vaccination program.

Four different types of vaccines are currently available.

• Attenuated (weakened) live virus is used in the measles, mumps, and rubella (MMR) vaccine and the varicella (chicken pox) vaccine. These vaccines last longer than other vaccines, but can cause serious infections in people with compromised immune systems.
• Killed (inactivated) viruses or bacteria used in some vaccines. For example, the pertussis vaccine uses killed virus. These vaccines are safe even in people with compromised immune systems.
• Toxoid vaccines contain a toxin produced by the bacterium or virus. For example, the diphtheria and tetanus vaccines are actually toxoids.
• Biosynthetic vaccines contain synthetic "man-made" substances. For example, the Hib (Haemophilus influenza type B) conjugate vaccine is a biosynthetic vaccine containing two antigens that are combined to form a "conjugate" molecule that triggers the immune system to produce antibodies that are effective against this disorder.
  

IMMUNIZATION SCHEDULE
The recommended schedule of immunizations is updated yearly by organizations such as the American Academy of Pediatrics (AAP). Consult your primary health care provider about the specific immunizations needed.

A recommended immunization schedule for children includes:

• Birth: HBV
• 2 months: Polio, DTaP, Hib, HBV, Pneumococcus
• 4 months: Polio, DTaP, Hib, Pneumococcus
• 6 months: Polio, DTaP, Hib, HBV, Pneumococcus
• 12 to 15 months: Hib, Pneumococcus, MMR, Varicella. The child may also be tested for TB (tuberculosis).
• 15 to 18 months: DTaP
• 4 to 6 years: Polio, DPT, MMR (Note: MMR may be delayed to age 11 to 12)
• 14 to 16 years: Td (repeat as a booster every 10 years)

A recommended immunization schedule for adults includes:

• Tetanus/diphtheria: A primary immunization series should be given once (if not received as a child), then routine booster doses of tetanus-diphtheria (Td) should be given every 10 years.

EXPLANATION OF VACCINE ABBREVIATIONS

• HBV: Hepatitis B vaccine (3 total doses recommended).

• Polio: Inactivated polio vaccine (4 total doses recommended). The oral polio vaccine is only used in select circumstances.

• DTaP: Diphtheria/tetanus/acellular Pertussis (3-in-1 vaccine; 5 total doses recommended). See DPT immunization (vaccine).

• Hib: Haemophilus influenzae type b conjugate vaccine (4 total doses recommended).

• Pneumococcus (Prevnar): Protects against certain forms of Strep. Pneumoniae (3 total doses recommended).

• MMR: Measles/mumps/rubella (3-in-1 vaccine; 2 total doses recommended). See MMR immunization (vaccine).

• Td: Adult tetanus/diphtheria (2-in-1 vaccine; for use in people over age 7). See Td vaccine.

WHERE AVAILABLE
Immunizations can be provided by the primary health care provider. The Health Department also provides immunizations, usually at a much lower cost than when obtained at the primary health care provider’s office.

TIPS FOR PARENTS
All of the current immunizations must be given as an injection (shot) because the acids in the stomach make most oral vaccines ineffective.

To make this experience easier for the child:

• Tell an older child what is going to happen. Explain that the injection is to keep the child safe and healthy. Knowing ahead of time what to expect may be reassuring for the child.
• Explain to the child that it is OK to cry, but suggest that the child try to be brave. Some children are reassured if the parent explains that they do not like injections either but they try to be brave. Praise the child after the injection is over.
• Distraction at the moment of the injection is helpful. For example, have the child look away (perhaps at a picture on the wall), have them count or say their "ABCs", or tell them something funny at the time of the injection. By the time the child finishes looking or laughing, the injection is over.
  

Plan something fun for after the injection. A trip to the park or playground, eating out, playing with the child, or other entertainment after the injection can make the next immunization experience less fearful.

OTHER IMMUNIZATIONS
Adults who have not been immunized as a child often are recommended to receive:

• Td (tetanus, diphtheria)
• MMR (measles, mumps, rubella)
• IPV (inactivated polio vaccine) **
• Influenza ("flu shot") *** -- Immunization for influenza is not recommended for all people. Elderly people and those at risk of serious illness should be vaccinated--see influenza immunization (vaccine).
• Pneumonia (pneumococcal pneumonia)*** -- See pneumococcal immunization (vaccine).

*** may be recommended in some situations.

IMMUNIZATIONS FOR TRAVEL
A booklet entitled "Health Information for International Travel" written by the Centers for Disease control and Prevention (CDC) lists which immunizations are required by travelers to each country in the world (ask your own health care provider for more information). The CDC also maintains a 24-hour International Traveler’s Hotline; call 1-404-332-4559.

The Public Health Service has indicated that only certain vaccinations are required by certain countries to which you may be traveling. However, other vaccines may be recommended, depending on the type and length of travel. Most immunizations should be obtained at least a month before travel.

Remember to take your immunization records with you when you travel internationally. International travelers may find themselves subject to unusual stressors (such as culture shock, jet lag, differences in altitude, temperature, and humidity, language frustrations, loneliness, and high-pressure schedules). Such stressors may leave the traveler at higher risk for acute medical problems, fatigue, depression, as well as substance abuse, sexual promiscuity and the potential health complications related to each. Because of the enhanced health risks for the international traveler, it is essential that personal health be maintained at an optimal level, health problems be known, and appropriate medications and medical records be carried with the traveler. The traveler should be aware of when, where, and what type of health care should be sought if the need arises.

Rabies vaccine may be necessary if bitten by an animal that is proven rabid, possibly rabid, or in which rabies immunity cannot be proven; or if traveling to and planning to spend more than 30 days in an area where rabies is common*. Occupations at higher risk include hunters, forest rangers, taxidermists, laboratory workers, stock breeders, slaughter house workers, veterinarians and spelunkers (cave explorers).

*Countries of particular concern include Thailand, Mexico, India, Nepal, the Philippines, Vietnam, Sri Lanka, Ecuador, Columbia, El Salvador, and most African and Asian countries. Rabies is prevalent in most of these countries. Any animal bite should be suspect. Dogs, skunks, raccoons, foxes, coyotes, and bats are the most commonly infected animals.