The K Health Guide to Vaccinations & Immunizations

By Howard Jeffries, MD
Medically reviewed checkmarkMedically reviewed
March 26, 2020

Every day, we are exposed to bacteria and viruses that can cause illness. Typically, your immune system can fend off sickness, but babies and small children have weaker immune systems and may need additional support to ward off germs. That’s where vaccines come in.

Vaccines use small amounts of antigens—the component of a virus or bacteria that triggers a person’s immune response—to strengthen the immune system and ward off specific, potentially life-threatening diseases. Diseases that were once rampant—like tetanus, pertussis (whooping cough), and polio—are far less common thanks to vaccines.

The Centers for Disease Control and Prevention (CDC) recommends an immunization schedule for children and adults in order to keep the general population healthy.

What Are Vaccinations?

Vaccines are treatments developed to prevent illnesses. Vaccines work by helping your immune system recognize and fight potentially harmful viruses or bacteria. Vaccines introduce antigens into your body, the part of the bacteria or virus that triggers the immune response. Once these antigens are introduced, your immune system produces antibodies to attack the germs before they cause sickness. Typically, vaccines are administered by injection but they can sometimes be given orally or nasally.

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Why Should I Vaccinate?

Vaccines aren’t just important for protecting your health—they protect the health of those around you. Vaccines lower your risk of contracting certain diseases, and they also help you prevent spreading them to those around you.

The CDC recommends vaccinations for all Americans, from birth into adulthood, and has created a vaccine schedule for babies and children. A doctor may recommend specific vaccines, or extra doses of immunizations, for adults with certain risk factors (like working in health care or being pregnant), or for those with medical conditions that compromise their immune systems. For example, an adult with kidney failure may need additional hepatitis vaccines.

You should also consider vaccinating yourself against diseases prevalent in other areas of the world. If you’re traveling to a particular country or region, it’s a good idea to look at the recommended vaccines by country. Doctors commonly recommend vaccines a month before international travel to give the body time to develop antibodies.

Common Diseases and Vaccines to Prevent Them

The U.S. currently uses vaccines to prevent 26 diseases, including some of the most common below:

5-in-1 or 6-in-1 vaccine

The 5-in-1 vaccine, a four-dose immunization, prevents against:

  • Diphtheria, a severe bacterial infection of the nose and throat
  • Tetanus, a bacterial infection that can cause muscle spasms and lockjaw
  • Pertussis, also known as whooping cough, a bacterial infection that causes uncontrollable coughing and sometimes, difficulty breathing
  • Polio, a virus that destroys spinal cord cells and can lead to paralysis
  • Hib disease, a bacterial infection that can lead to a serious brain infection in young children

The 6-in-1 vaccine protects against all of the above, plus hepatitis B, a viral infection that attacks the liver.

A booster of Hib vaccine is generally not needed if a child already received all four doses of the 5-in-1 immunization.

Chicken pox vaccine

The chicken pox vaccine protects against chicken pox, also called varicella, which can cause an itchy, raised rash and flu-like symptoms. Children receive the chicken pox vaccine twice: once between ages 12-15 months and again between ages four to six.

The CDC also recommends adolescents and adults who were never vaccinated to undergo the same chicken pox vaccine schedule.

Diphtheria-tetanus-acellular pertussis (DTaP) vaccine

The DTaP vaccine protects against three illnesses:

  • Diphtheria, an infection that causes a thick covering in the back of the throat. It can lead to difficulty breathing, heart failure, and paralysis.
  • Tetanus, an infection that can affects the brain and nervous system leading to serious muscle spasms and eventually causing death
  • Pertussis, also called whooping cough, can lead to bad coughing and difficulty breathing and is dangerous for infants.

Children usually get five doses of the DTaP vaccine between two months and six years of age.

The DTaP vaccine is only for children younger than seven. According to the CDC, the DTaP vaccine isn’t appropriate for every child; some children receive a different vaccine that only contains diphtheria and tetanus. Talk to your doctor if your child has:

  • Any severe allergies
  • Had an adverse reaction to a previous dose of DTaP
  • Seizures or another nervous system condition
  • Guillain-Barre syndrome (GBS)

In some of the above cases, your child’s doctor might postpone the DTaP immunization.

HPV vaccine

The HPV vaccine protects against HPV, or human papillomavirus, a common virus that can lead to six types of cancers. The CDC recommends children get two doses of the HPV vaccine, once between the ages of 11-12 and again 6-12 months after the initial dose.

HPV vaccination is also recommended for those up to 26 years old who haven’t received the HPV vaccine already.

Hepatitis A

The hepatitis A vaccine protects against hepatitis A, a serious liver disease. The hepatitis A vaccine is a two-dose immunization that starts at 12 months of age.

In special cases, such as travel to an area where hepatitis A is more common, doctors might shift this schedule to vaccinate sooner. Unvaccinated individuals older than one year of age should receive a dose as soon as travel is considered.

Hepatitis B vaccine

The hepatitis B vaccine protects against hepatitis B, which also results in serious liver disease. The CDC recommends babies receive three doses of the hepatitis B vaccine before 15 months of age.

For those with immunocompromising conditions, such as cancer patients in chemotherapy, the CDC recommends an additional vaccination to ensure immunity.

Influenza vaccine

The influenza vaccine, also called the flu shot, protects against influenza, a potentially dangerous upper respiratory infection. Flu shots are developed yearly as the influenza virus changes rapidly.

MMR (measles mumps rubella) vaccine

The MMR vaccine protects against three diseases:

  • Measles, also called rubeola, a viral infection that can cause flu-like symptoms and a blotchy, red rash
  • Mumps, a viral infection that can cause flu-like symptoms and severe swelling of one or both salivary glands
  • Rubella, also called German measles, a viral infection that can cause flu-like symptoms and a distinct, red rash

Children receive the MMR vaccine twice. The first dose is usually between 12-15 months, and the second dose is usually between ages 4-6.

Adults who don’t have evidence of immunity to measles, mumps, and rubella (even if they received the vaccine as children) should also receive an additional dose, especially if they work in health care or are traveling to areas where these illnesses are more common.

Meningococcal vaccine

The meningococcal vaccine protects against meningococcal meningitis, a potentially dangerous bacterial infection that causes inflammation in the membranes covering the brain and spinal cord, and sepsis caused by meningococcal bacteria. Children get their first dose of the meningococcal vaccine at ages 11-12 with a second dose around age 16.

Pneumococcal vaccine

The pneumococcal vaccine protects against pneumococcus bacteria, which can cause pneumonia, meningitis, and a variety of upper respiratory infections. This vaccine is given in four doses at ages two months, four months, six months, and 12-15 months.

An additional dose may be given to children older than age ten if a doctor determines a higher risk for pneumococcal complications.

Rotavirus vaccine

The rotavirus vaccine protects against rotavirus, which can cause severe diarrhea, vomiting, and dehydration. Children usually get the rotavirus vaccine three times at two, four, and six months of age. Another version of the rotavirus vaccine is two doses.

Vaccine Schedule By Age

The CDC recommends vaccinations based on your age. Your child’s doctor will offer vaccines according to the CDC’s schedule, and your provider will likely offer the influenza vaccine if you visit around flu season.

Some vaccines require multiple doses over the course of several years, and there are special cases when a child may need an extra dose of an immunization. Remember that if you delay vaccines, you increase you or your child’s risk of exposure to illnesses that can be serious or even life-threatening.

For children under age 18, the CDC breaks down the vaccine schedule in two categories: birth to 15 months and 18 months to 18 years:

Birth to 15 months

  • Hepatitis B (HepB)
  • Rotavirus (RV)
  • Diphtheria, tetanus, and acellular pertussis (DTaP)
  • Haemophilus influenzae type b (Hib)
  • Inactivated poliovirus (IPV)
  • Pneumococcal conjugate (PCV13)
  • Influenza (IIV or LAIV)
  • Measles, mumps, and rubella (MMR)
  • Varicella (VAR)
  • Hepatitis A (HepA)
  • Human papillomavirus (HPV)
  • Meningococcal (MenACWY-D: ≥9 mos; MenACWY-CRM: ≥2 mos)
  • Meningococcal B (MenB)
  • Pneumococcal polysaccharide (PPSV23)

18 months to 18 years

  • Hepatitis B (HepB)
  • Rotavirus (RV) RV1 (2-dose series); RV5 (3-dose series)
  • Diphtheria, tetanus, and acellular pertussis (DTaP: <7 yrs)
  • Haemophilus influenzae type b (Hib)
  • Pneumococcal conjugate (PCV13)
  • Inactivated poliovirus (IPV)
  • Influenza (IIV or LAIV)
  • Measles, mumps, and rubella (MMR)
  • Varicella (VAR)
  • Hepatitis A (HepA)
  • Tetanus, diphtheria, and acellular pertussis (Tdap: ≥7 yrs)
  • Human papillomavirus (HPV)
  • Meningococcal (MenACWY-D: ≥9 mos; MenACWY-CRM: ≥2 mos)
  • Meningococcal B (MenB)
  • Pneumococcal polysaccharide (PPSV23)

To learn more about age-based vaccine recommendations for your child, and to make sure they are up to date, talk to your child’s primary care provider or chat with a K doctor.

To learn about vaccines for adults, talk to your provider, chat with a K doctor, or view the CDC’s recommendations for adult immunizations.

Research and Resources

A strong and growing body of scientific research suggests that vaccines are a safe, effective, and necessary way to prevent disease. Vaccination protects children from serious illnesses and their complications, which can include lifelong disability and even death.

Immunization is also important for public health. For example, young babies and those with weaker immune systems are at risk for certain diseases. Unvaccinated individuals could spread harmful diseases to these vulnerable people.

Some parents are concerned about the safety of vaccines. While some vaccines come with mild side effects, like a low-grade fever, vaccines are tested and closely monitored to ensure their safety and effectiveness.

To learn more about vaccines, how they work, and why they are important, read the following trusted resources:

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K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Howard Jeffries, MD

A pediatric cardiac intensivist at Seattle Children's Hospital, Dr. Jeffries is also Senior Medical Director, Regional Network. He completed a residency in pediatrics and a fellowship in pediatric intensive care. He has published chapters and peer-reviewed articles, with an emphasis on cardiac intensive care, informatics, outcomes assessment and quality improvement.

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