How Vaccines Work

By: Alia Hoyt  | 

Childhood Vaccinations

man with polio, Nigeria
A man whose legs and feet are twisted and wasted as a result of polio has his toenails trimmed and cleaned by a friend in Lagos, Nigeria, 2003. The polio virus often causes wasting of the lower limbs. The polio vaccination has saved millions around the world from getting polio. Jacob Silberberg/Getty Images

Early childhood: From age 18 months to 6 years, children receive subsequent vaccinations of HepB, DTaP, IPV, MMR and varicella. This is to ensure maximum protection against the diseases.

Later childhood/adolescence: After age 6, children don't have too many shots to worry about until adolescence. Around age 11 they should get the DTaP vaccine to protect against tetanus, diphtheria and pertussis because the vaccine they received as an infant has worn off. The following are also recommended at age 11 to 12:


  • HPV (human papillomavirus): This two-dose shot is one of the newer vaccines. HPV is a sexually transmitted disease that causes cervical and genital warts. HPV is usually symptom-free, so women become aware of the infection only when they have a positive Pap smear. It's also recommended for women up to age 26 who have not already received it.
  • MCV4 (meningococal): The disease occurs when the spinal fluid and fluid around the brain become infected. The symptoms of meningitis are high fever, headache and a very stiff neck. It can be viral or bacterial (bacterial is the most severe) and is sometimes contagious, depending on the bacteria. This is why middle- and high-school students, as well as college students living in dormitories, are recommended to get the shot. A booster shot is recommended at age 16.

Young people also need a booster for pertussis, better known to many as whooping cough. Most infants receive the vaccine, but it wears off by adolescence. Many teens and parents aren't aware that middle-school-age children should receive a booster vaccine to protect themselves and others.

While teens and adults can catch and suffer from the disease, it's often fatal to the very young and very old. Babies receive the vaccine in three doses, so they aren't protected completely from the disease for many months. According to the CDC, most infant deaths from pertussis occur in babies under 3 months old. The elderly and people with poor immune systems are also at elevated risk because their immune systems are much weaker.

"The point is that if you are around an elderly person or a baby you really need to have this shot," says Joyce Allers, R.N., of Children's Healthcare of Atlanta. "We as a society have to protect our more fragile members. They [people whose children are not up-to-date on vaccines] are taking their child out in public where they may be exposing a grandfather recovering from cancer to a potentially deadly disease."

Pertussis is often misdiagnosed because it shares symptoms with other common respiratory ailments. Symptoms include a severe cough that can last eight weeks or more, momentary loss of consciousness, low-grade fever and a runny nose.

Adults have to get shots, too. Find out about them on the next page.