by Dr. Edith Bracho-Sánchez, American Academy of Pediatrics

Credit: CC0 Public Domain

Have you ever wondered why babies get vaccines starting from the day they're born? One big reason: The youngest are most at risk of diseases. It's also the time in your child's development that their immune system learns the most from vaccines.

August is National Immunization Awareness Month, a good time to check whether your child is up to date on vaccines, which help to provide immunity before kids are exposed to potentially life-threatening diseases. Of all age groups, babies are more often hospitalized, and sometimes die, from diseases we can prevent with vaccines. That's why most of the childhood vaccines are recommended during your baby's first 12 to 18 months of life.

The Centers for Disease Control and Prevention, the American Academy of Pediatrics and other medical groups have all agreed on a schedule for immunizations for kids. The recommended schedule is based on research showing us the best timing for each vaccine dose.

Your pediatrician keeps track of your child's vaccines. They make sure your child is protected at the right time.

Hepatitis B is the first vaccine most babies receive. It is given within 24 hours of birth. Your baby will get a second dose of hepatitis B vaccine when they are 1 month to 2 months old and the third dose when they are 6 months to 18 months old.

Why do we give the first dose so quickly? More than 1 million people in the U.S. have long-term hepatitis B infections. People who are infected with hepatitis B as a baby have a 90% chance of developing serious, chronic conditions like liver cancer in their lifetime. And because people may not know they are infected, they may spread the virus if they come in close contact with your baby. The vaccine is a safe, effective way to eliminate that risk right away.

2 months old

The first doses of the vaccines given at 2 months of age protect babies from seven diseases. The letters stand for the diseases that used to cause serious infections in children.

Children get five doses of diphtheria, tetanus and acellular pertussis (DTaP) vaccine, which prevents serious illness from three diseases:

• Diphtheria: A serious throat infection that can cause breathing problems and heart failure. Before the vaccine, diphtheria killed one-fifth of the kids who got infected.

• Tetanus: A deadly bacteria that lives in the soil and is found everywhere on the earth. It can get into your body through a rusty nail or any kind of cut on your skin. Tetanus is also called "lockjaw" because one of the most common signs of infection is tightening of the jaw muscle.

• Pertussis: Also called "whooping cough," it causes violent coughing fits that make it hard to breathe. Babies with pertussis may need hospital care and are at risk of death. Often, pertussis is spread to the baby by an adult or sibling who does not know they have it.

Haemophilus influenzae type B (Hib) vaccine (three to four doses) prevents several types of illness, including ear infections, lung infection, swelling in the throat and swelling in the lining of the brain and spinal cord (meningitis). Infections can be life-threatening. If babies have not been vaccinated and have symptoms of meningitis, they may need a spinal tap to test the spinal fluid for the bacteria.

Polio (IPV) vaccine (four doses) prevents a disease that causes death and paralysis. Polio outbreaks still occur in the United States, so unvaccinated children are at risk.

The pneumococcal vaccine (four doses) prevents disease caused by bacteria called Streptococcus pneumoniae. When these bacteria invade the lungs, they cause pneumonia. When they invade the bloodstream, they can cause an overwhelming infection called sepsis. When they invade the tissue around the brain, they cause meningitis. They can also cause ear infections, which can be painful and occur frequently. Since we have had this vaccine, the number of kids developing these illnesses has dropped dramatically.

Rotavirus (RV) vaccine (two or three doses) stops the main cause of diarrhea in children. This virus spreads very easily—on your hands, soiled diapers or toys and through the air. Rotavirus infections cause severe, watery diarrhea, vomiting, fever and abdominal pain. Sometimes the virus causes children to become so dehydrated they need hospital care.

6 months old

The COVID-19 vaccine is recommended for everyone starting at 6 months of age, with rare exceptions. Young children are especially at risk if they get sick. The vaccine can help protect against severe complications, including pneumonia (infection in the lungs), respiratory failure, blood clots, bleeding disorder, injury to liver, heart or kidney, multisystem inflammatory syndrome, post-COVID conditions and death.

The flu vaccine is recommended for everyone starting at 6 months of age, with rare exceptions. The first time your child gets the flu vaccine, if they are younger than 9 years old, they will also need a second dose four weeks later. Even healthy kids can develop severe complications from the flu that requires a hospital stay. Flu viruses change from year to year, so everyone needs to get a flu shot each year. Annual flu shots keep children from severe disease.

12 to 18 months old

At your child's first birthday checkup or soon after, they will get shots that protect them from five more diseases. They also may get second, third or fourth doses of the vaccines they started during the first year.

Children get two doses of the measles, mumps, and rubella (MMR) vaccine. Some children at higher risk may need three doses in the event of a disease outbreak. Most people who are vaccinated with MMR will be protected for life. The vaccine prevents serious illness from three diseases:

• Measles can cause rash, fever, cough, runny nose and pink eye (conjunctivitis). It can lead to seizures (often associated with fever), ear infections, diarrhea and pneumonia. Rarely, measles can cause brain damage or death.

• Mumps can cause swollen salivary glands (under the jaw), fever, headache, muscle aches and tiredness. It can lead to deafness, swelling of the brain and/or spinal cord covering, painful swelling of the testicles or ovaries, and very rarely, death.

• Rubella can cause fever, sometimes rash, and swollen lymph nodes. A pregnant person who gets rubella could have a miscarriage or the baby could be born prematurely or have serious birth defects.

Varicella vaccine (two doses) prevents "chicken pox," which used to infect 4 million people in the United States every year. A mild case can cause a child to miss school for a week or more. Usually, the MMR vaccine and varicella vaccine are given separately for the first dose. But the MMRV vaccine may be used for the first dose instead if parents express a preference.

Hepatitis A vaccine (two doses given six months apart) provides lifelong protection from a serious liver disease. The disease can spread through contaminated food or water or direct contact with an infected person—even someone who doesn't show symptoms.

Vaccines also protect babies before birth. Babies get antibodies during pregnancy from some vaccines their mothers have had. For example, the baby is protected for a short time after they are born if their mother has had the measles vaccine.

However, this protection moms give their babies during pregnancy starts to wear off at around 1 year of age. That's why, when they are 12 months to 18 months old, babies get a shot to keep their immune system protected them from measles.

We know from decades of research, in millions of children, that the vaccines work best at these ages, and with this spacing between doses.

When they follow the schedule, children develop lasting immunity—and protect others—from serious diseases. If you have questions, talk with your pediatrician. We are here to partner with you to help your child stay healthy and thrive.

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