School supplies and new clothes aren't the only back-to-school essentials. Childhood vaccinations also top the list of must-haves. Whether you're dropping your young one off at preschool or shuttling a high school graduate off to college, getting your children immunized on time will help them stay healthy long after the school year ends.

Vaccines protect individuals from infectious diseases like measles and mumps, but staying up to date on your child's immunizations can also help keep the school and community healthy, too. Children that are too young to be immunized, have medical conditions that make vaccinations unsafe or don't respond well to certain vaccines are better protected if children around them have immunity.

Every school's immunization policy is different, and most requirements vary by state, but there are a number of must-get vaccines. Brush up on shot knowledge and help your student get fully prepared for the first day.

1. Diphtheria, Tetanus and Acellular Pertussis (DTaP)

The DTaP vaccine protects against three serious bacterial diseases: diphtheria, tetanus and pertussis.

  • Diphtheria is characterized by a thick coating in the back of the throat and can cause breathing trouble, heart failure and paralysis.
  • Tetanus causes the body's muscles to tighten, which can lead to jaw cramping, spasms, seizures, headaches and blood pressure and heartrate changes. Complications include trouble breathing, pneumonia, infections contracted during hospital visits, pulmonary embolisms and even death if left untreated.
  • Pertussis, or whooping cough, is a respiratory illness marked by coughing fits that can last for weeks and prevent infants from eating, drinking and breathing. Pneumonia, seizures and brain damage are all possible repercussions of the condition.

Children should receive five doses of the DTaP vaccine between 2 months and 6 years and a booster known as Tdap between ages 11 and 12.

The immunization isn't safe for everyone. Children who have a life-threatening allergic reaction to DTaP or experience a brain or nervous system disease within a week of the shot should not receive another dose. Children sick with a severe cold or flu should wait to be vaccinated.

2. Inactivated Poliovirus

It's recommended that children be vaccinated against polio with a four-dose series between 2 months and 6 years.

Polio is a disease caused by a virus spread through contact with an infected person or by consuming food contaminated with the feces of someone who has been infected. Polio has been eliminated in the U.S. for almost 40 years, but still affects people in a few other countries, making immunizations important for keeping the U.S. disease-free.

3. MEASLES, MUMPS AND RUBELLA (MMR)

The MMR vaccine protects against measles, mumps and rubella, diseases which are highly contagious and easily spread.

  • Measles typically presents with a fever, cough, runny nose and a rash that covers the entirety of the body. The condition can lead to pneumonia, diarrhea and, rarely, brain damage.
  • Mumps cause head and muscle aches, fatigue and swollen and tender salivary glands. The virus can cause brain and spinal cord swelling, deafness, testicular and ovarian swelling and miscarriage.
  • Rubella virus is characterized by a fever, sore throat, rash and eye irritation. The condition can increase miscarriage risk in pregnant women and leads to arthritis in nearly half of teen girls and women who contract the disease.

Most children should receive two doses of the MMR vaccine - the first between 12 and 15 months and a second between 4 and 6 years, but those who miss the recommended age targets should be immunized with two doses at least 4 weeks apart.

The vaccine isn't suitable for everyone, including those with allergies or a weakened immune system caused by HIV/AIDS, chemotherapy or radiation. Tell your child's doctor is there's a family history of immune disorders, your child has a bleeding condition or bruises easily, has tuberculosis or has received a blood transfusion within the last 90 days.

4. Hepatitis B

Between birth and 18 months, children should receive three doses of the hepatitis B vaccine to help ward off the virus that causes liver inflammation and symptoms like a fever, chills, body aches, pale stool, dark urine and jaundice.

Immunization is especially important during childhood; adults typically recover fully from exposure to the virus, but it's more likely children will develop a chronic infection. Long-term complications include liver failure, liver cancer or cirrhosis, which leaves the liver permanently scarred.

Certain circumstances can change when a child should be vaccinated.

  • Healthy infants born to mothers who test negative for the hepatitis B antigen should receive their first dose within 24 hours of birth.
  • Newborns with a low birth weight - under 4.4 pounds - will receive their first shot at 1 month or upon being discharged from the hospital.
  • The vaccine will be administered within 12 hours of birth to children born to mothers with hepatitis B, regardless of weight.
  • A pregnant woman with hepatitis B can transmit the disease during birth, and one-fourth of infected newborns will eventually succumb to liver disease caused by the virus. Speedy vaccination can help prevent this.

5. Varicella (Chickenpox)

Chickenpox is a highly contagious disease characterized by itchy blisters covering the body (or a portion of the body), fever and fatigue. Cases of chickenpox are common in the U.S. and usually require no treatment, but the condition can be uncomfortable. In rare cases, it can lead to infections, dehydration, pneumonia or brain swelling.

The surest prevention method is the varicella or chickenpox vaccine, and children should receive two doses:

  • The first between 12 and 15 months,
  • and the second between 4 and 6 years, although the second dose can be give as early as 3 months after the first.

Although it's recommended to have children vaccinated on time, children of all ages can receive the vaccine.

The vaccine is safe and effective for most, but parents of children who develop a severe allergy to the vaccine or who have conditions or are taking medications that compromise their immune systems should consult the child's doctor about potential risk.

6. Haemophilus Influenzae Type B

The Haemophilus influenzae type b, or Hib vaccine, protects against a type of bacteria that can cause meningitis or brain and spinal cord swelling, pneumonia, severe throat swelling and even death. The bacteria typically affects children under 5 years of age, so immunization is recommended beginning at 2 months.

Depending on the specific brand of vaccine, some children may need up to four doses, while others will need three. Children on the three- and four-dose series should receive a shot at 2 months, 4 months and between 12 and 15 months. Those receiving a fourth shot will also get a dose at 6 months.

7. Pneumococcal Conjugate

Pneumococcal disease can cause ear infections, but it can also lead to more serious concerns like lung or blood infections or brain and spinal cord swelling (meningitis). Although pneumococcal pneumonia most often affects adults, children who contract pneumococcal disease that leads to meningitis might experience deafness and brain damage and in 10 percent of cases, death.

Children under 2 years of age should receive four doses of the pneumococcal conjugate vaccine, at:

  • 2 months
  • 4 months
  • 6 months
  • between 12 and 15 months

Most children have only minor reactions to the vaccine, which may include drowsiness, mild fever and swelling, redness or tenderness at the injection site, but reactions can happen and may include severe shoulder pain or an allergic reaction.

Children who miss recommended doses should still be vaccinated - it's never too late. Speak with a healthcare provider for next steps if your child is behind schedule.

8. Meningococcal

The Neisseria meningitidis bacteria can cause brain and spinal cord swelling, known as meningitis, or a blood infection, called bacteremia or septicemia. Meningococcal disease can cause rapid organ failure and become deadly very quickly.

  • To safeguard your children from these diseases, they should be immunized between 11 and 12 years of age with a meningococcal conjugate vaccine and receive a booster shot at 16 years old.
  • Teens between 16 and 18 may also receive a serogroup B meningococcal vaccine, which can be given at a younger age to those with certain disorders, a damaged or removed spleen or who are taking Soliris.

Parents of children with serious allergies of any kind - to this or any other vaccine - should speak with a healthcare provider before getting them vaccinated.

9. Influenza

Anybody can get the seasonal flu, a viral infection that wreaks havoc on the respiratory system, and can cause high fever, muscle aches, nasal congestion, a sore throat and a dry cough. Not everyone who contracts the flu will have a severe case, but children under the age of 5, and especially those under 2 years old, are at a higher risk.

A yearly flu vaccine is recommended for most people, excluding children younger than 6 months and those allergic to the vaccine or any of its ingredients. Young children who get immunized for the first time will likely need an extra dose. Children between 6 months and 8 years of age who are receiving the flu vaccine for the first time, should receive two doses separated by at least 28 days. A single dose is recommended every year thereafter.

The US Centers for Disease Control and Prevention (CDC) suggests getting the flu vaccine before the end of October, although there is still benefit to being vaccinated any time during flu season.

For guidance on when or why to vaccinate your child for these and other diseases, speak with your family doctor.