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UC Davis Health System

UC Davis Health System

Time for new books, backpacks – and a visit to the doctor for immunizations

children riding school bus
Back-to-school time is a good opportunity to make sure that children have all of their necessary vaccines.

Posted Aug. 22, 2012

As another school year begins, it is important for all school-aged children to be up-to-date with all of their immunizations, because they will be interacting with a larger group of children and therefore at greater risk of exposure to preventable infectious diseases.

The number of vaccines available and required has grown significantly over the years, from under five in 1900 to 16 in 2000 to nearly two dozen today. It can be frustrating to parents and children that so many shots are recommended, but it is important to remember that each inoculation is meant to protect against diseases that pose significant health risks. These inoculations all are great advances in ensuring children's health, now and into the future.

"Many people are concerned that the number of shots may be too much, and that too many vaccine constituents may be harmful," said Dean Blumberg, chief of the division of pediatric infectious diseases in the Department of Pediatrics in the UC Davis School of Medicine. "However, even though more injections occur now, the vaccines we use today are highly purified and include only those components necessary to provide protection," Blumberg said.

How vaccines work

There are two main types of vaccines, inactivated and live. Inactivated vaccines contain purified but dead components of pathogens, such as tetanus. When the body encounters these components, the immune system is in charge of making antibodies against them. Then if one were to encounter the real thing, the immune system is primed to fight it off. The first polio vaccine introduced by Jonas Salk in 1955 was of this variety.

Live vaccines are weakened forms of the pathogens, like measles vaccine. Although they are not as strong as the strains that occur in nature, they are able to multiply and cause a subclinical infection mild enough that there are usually no symptoms. The immune system fights it off, and then the person is protected if they encounter the natural pathogen.

Vaccines may cause local reactions, such as pain and redness at the site of the injection, and can cause fever as well, but are otherwise generally well-tolerated. There continues to be no scientific evidence that vaccines "overwhelm the immune system," cause autism, or other allegations. These concerns have been studied extensively and are unfounded.

Recommended immunization schedule

This childhood inoculation schedule is recommended by the American Academy of Pediatrics (AAP), in consultation with the Advisory Committee on Immunization Practices of the U.S. Centers for Disease Control and Prevention (CDC) and the American Academy of Family Physicians.

child getting checkup with family doctor © iStockphoto
Families should work with their pediatrician to stay on top of vaccination schedules.

  • Preschool children: Kids ages 2 to 4 should have received four doses each of DTaP (diphtheria, tetanus and acellular pertussis), PCV (pneumococcal conjugate vaccine) and Hib (haemophilus influenzae). They also should have received three doses each of IPV (inactivated polio vaccine), hepatitis B, and one dose each of the MMR (measles, mumps and rubella) and varicella (chicken pox) vaccines. The number of shots may vary depending on the combination of vaccines your health care provider uses.
  • 4- to 6-year-olds: Children entering kindergarten should receive any immunizations that they've missed or receive a booster -- a supplementary dose -- of DTaP, IPV and MMR. Consult your provider.
  • Pre-adolescents and teens: In California, adolescents are required to receive a Tdap booster before entering 7th grade. Adolescents 11 years old and up are required to receive the MCV4 (meningococcal conjugate vaccine). Those who never received the varicella vaccine or who have not had the illness should get that shot. Girls at this age should receive the HPV vaccine.

For children who have gotten behind on their vaccinations it's not too late. Both the CDC and AAP offer guidelines on how to catch up. Families should contact their child's physician for help getting them back on track.

UC Davis Children's Hospital is the Sacramento region's only nationally ranked, comprehensive hospital for children, serving infants, children, adolescents and young adults with primary, subspecialty and critical care. It includes the Central Valley's only pediatric emergency department and Level I pediatric trauma center, which offers the highest level of care for critically ill children. The 129-bed children's hospital includes the state-of-the-art 49-bed neonatal and 24-bed pediatric intensive care and pediatric cardiac intensive care units. With more than 120 physicians in 33 subspecialties, UC Davis Children's Hospital has more than 74,000 clinic and hospital visits and 13,000 emergency department visits each year. For more information, visit children.ucdavis.edu.