• A shot for your health."Science Experiment" is Copyrighted by Flickr user: Shermeee (Sherman Tan) under the Creative Commons Attribution license.
  
  

Immunity

• There are two types of immunity---active and passive. Active immunity is the longer lasting of the two and occurs when the body's immune system creates antibodies to fight off an invading organism. This can occur through exposure to the actual disease or from a version contained in a vaccine. Passive immunity only lasts for a short time---a few weeks to a few months---and occurs when a person does not create antibodies through their immune system but rather is given them instead, per the CDC.
  
  

Schedule

• Vaccinations generally begin right after birth, with the typical infant schedule running until the child's second birthday. Some immunizations need only one shot, while others require numerous ones spread out over a specific time frame, to achieve full effect. Teens and adults need regular vaccines too, for such diseases as bacterial meningitis and tetanus. A complete record of all vaccines may be necessary for schools, summer camp and traveling abroad.
  
  

Side Effects

• Side effects are common in any medication, and vaccinations are no different. Most side effects are minor, such as a sore injection area or low fever and disappear within a few days. Sometimes they can be more serious, which is why it's very important to monitor the behavior and health of a recent vaccine recipient for a few days after receiving the shot. Each vaccine has a different list of possible side effects, so ask your doctor what to watch out for. Some typical side effects include headaches, tiredness and irritability, according to the CDC.
  
  

Safety

• Many people are worried that vaccines are unsafe, and cause more problems than they prevent. However the FDA requires vaccines to be tested thoroughly before they are licensed and available for public use, which can take 10 years or more depending on the vaccine in question. Any adverse reactions or side effects are monitored via the Vaccine Adverse Event Reporting System---or VAERS---and prompt further testing, investigations and action by the FDA and CDC.
  
  

Warning

• The CDC states that despite the advantages associated with vaccines, certain people should either not get them at all or wait. Anyone with a compromised immune system, such as cancer patients or those with HIV/AIDS, should consult their doctor before accepting any vaccinations. Certain vaccines should also be postponed if the patient is ill, or has had an allergic reaction to a previous dose. Some vaccines are cultured inside eggs, so anyone with an egg allergy should not receive that vaccine.