Childhood Vaccination Schedules
Vaccines have played one of the most significant roles in advancing public health in modern history.
Through vaccination, smallpox has been eliminated from the world and cases of diphtheria and polio are no longer seen in the United States. The occurrence of measles, mumps, German measles, and some forms of meningitis have been reduced by more than 95 percent; reports of whooping cough and chicken pox have dramatically decreased.
The success of vaccination programs has spurred the development of many new vaccines. It is a marvel that today’s children and adolescents can be vaccinated to prevent disease caused by 16 different infectious agents. But rapidly changing vaccine schedules are often difficult for parents and medical providers alike to comprehend.
The suggested timing of childhood immunizations can generally be divided into three distinct time periods in a child’s life: infancy and toddlerhood, preschool, and early adolescence. Emmanuel (Chip) B. Walter, MD, MPH, describes the schedule below.
-- Dennis Clements MD, PhD, MPH
Emmanuel (Chip) B. Walter, MD, MPH
Vaccines for Infants and Toddlers
The first vaccine a child receives should be the initial dose of the hepatitis B series administered before a newborn is discharged from the hospital after birth.
This immunization prevents the transmission of hepatitis B from the mother to the infant and thereby decreases the chance that the child will have chronic active liver disease.
At the two month well-child visit, several vaccine series commence including:
- DTaP series: prevents diphtheria, tetanus, and pertussis (whooping cough)
- Polio series: prevents three paralytic polio virus types
- Haemophilus influenzae type B (Hib) series: prevents a form of bacterial meningitis, pneumonia, and serious infections of the blood, airway, joints, bones, and skin
- Pneuomococcal series: prevents another form of bacterial meningitis, pneumonia, blood infections, and ear infections
- Rotavirus series: a vaccine given by mouth to prevent the most common cause of severe infant diarrhea (viral cause)
Most of the subsequent doses in the vaccine series given during the first year of life are timed to coordinate with well-child checks at four- and six-months-old.
During a child’s second year several additional vaccines are recommended by the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices and by the American Academy of Pediatrics Committee on Infectious Diseases. These include:
- DTaP booster (see above)
- Hib booster (see above)
- Pneumococcal booster (see above)
- MMR: prevent measles, mumps, and rubella (German measles)
- Varicella: prevents most chicken pox viral disease
- Hepatitis A series: prevents liver infection due to hepatitis A virus; second dose required after six months to finish series
The exact timing and number of doses of each vaccine given to children often depends on the brand of vaccine used by your child’s health care provider.
For example, the total number of doses of Hib vaccine may be either three or four and the total number of doses of rotavirus vaccine may be two or three depending on the brand of vaccine your child receives. Many states (like North Carolina) use state-supplied vaccines, so the schedule varies based on what vaccine brand is provided by the state.
Vaccines Prior to School Entry (Ages Four to Six)
Prior to school entry, between four and six years of age, it is recommended that children receive the following immunizations:
- DTaP booster
- Polio booster
- MMR vaccine (second dose)
- Varicella vaccine (second dose)
Second doses of MMR and chicken pox vaccines are suggested because a significant proportion of children remain unprotected from measles or chicken pox after receiving the first dose of vaccine.
Vaccines in Early Adolescence (Ages 11 to 12)
Several vaccines are now recommended in early adolescence including:
- Tdap: boosts protection to tetanus, diphtheria, and pertussis (In North Carolina, children entering sixth grade as of August 1, 2008, will be required to receive a dose of Tdap prior to school entry)
- Meningococcal conjugate vaccine: prevents deadly bacterial blood infection and meningitis to which adolescents are more prone
- Human papilloma virus (HPV) vaccine series (for females only): prevents cervical cancer and genital warts
Annual Influenza (Flu) Vaccine (Ages Six Months to 18 years)
Besides these periodically recommended vaccines, it is also suggested that all children between six months and 18 years of age receive an annual flu vaccine.
Children under five years of age are at higher risk of complications from flu that lead to hospitalization. In addition, by routinely vaccinating school age children you can decrease the spread of flu to others in the household and community. If it is the first time an infant is receiving a flu shot, a booster dose one month later is required.
Combination Vaccines
With the abundance of recommended vaccinations, children under the age of two years could potentially receive as many as 25 different injections and three oral vaccines.
Fortunately several combination vaccines are available to reduce the number of injections a young child must endure. The following combination vaccines are currently approved for use in children:
- Hib–hepatitis B vaccine
- DTaP–hepatitis B–polio vaccine
- DTaP–polio–Hib vaccine
- MMR–varicella vaccine
In addition to decreasing the injection-related pain for young children, the use of combination vaccines reduces the potential for errors occurring while administering vaccines and improves adherence to recommended vaccine schedules.
Are There Too Many Vaccines?
Many parents wonder if the increased number of vaccines is harmful because children are being exposed to too many antigens -- substances that create an immune response.
Children are exposed to a large number of antigens through daily life. Eating food introduces new bacteria into the body and any time a child experiences a cold or common infection they are exposed to a significant number of new antigens.
Current vaccines have actually reduced the number of antigens to which a child is exposed compared to vaccines used in earlier years. So even though the number of shots has increased, the number of antigens to which a child is exposed has decreased.
We are fortunate that today’s children do not have to die or suffer from complications due to measles, polio, or meningitis. But there is continued work to be done at preventing other childhood diseases -- particularly infections due to respiratory viruses that are common causes of pneumonia in young children.
It is likely the number of diseases able to be prevented through vaccination will continue to increase and the childhood immunization schedule will continue to evolve.
-- Emmanuel (Chip) B. Walter, MD, MPH, is Director of the Duke Translational Medicine Institute Clinical Vaccine Unit and he is Associate Director of the Primary Care Research Consortium at the Duke Clinical Research Institute.
-- Dennis Clements, MD, PhD, MPH, is the chief of primary care pediatrics at Duke Children's Hospital.
