Checkup on health: The importance of vaccines
By Dr. Dean Blumberg
Blumberg, an associate professor at UC Davis Children's Hospital, specializes in pediatric infectious diseases.
As another school year begins, it is important for school-aged children to be up-to-date with all of their immunizations, as they will be interacting with a larger group of children and therefore at higher risk of disease. Specifically, there have been recent school outbreaks of whooping cough, measles, mumps and varicella, so it is important for children attending school to receive these shots.
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 shot is meant to protect against important diseases. These are all great advances in ensuring health, now and in the future.
"Each shot is meant to protect against important diseases. These are all great advances in ensuring health, now and in the future."
— Dean Blumberg, pediatric infectious disease specialist
A good number
Many people are concerned that the number of shots may be too much, and that too many vaccine constituents may be harmful. However, even though more injections occur now, the vaccines we use today are highly purified, and include only those components necessary to provide protection.
Some new vaccines are designed to target specific disease threats. There is a new vaccine for rotavirus (the most common cause of severe diarrhea among children), and a new human papillomavirus (HPV) vaccine is just around the corner. At UC Davis we are doing a study with a new vaccine to help prevent meningitis, giving it earlier in life (7-9 months of age) to see if we can get children protected against this deadly disease sooner.
Other new vaccines are combinations of existing vaccines designed to create need for less shots. One released this year covers diptheria, tetanus, whooping cough, polio and Hib (a cause of meningitis) in a single injection.
Things to remember
Some important information to note about immunizations:
- It's important for infants to get their diphtheria-tetanus-whooping cough (DTaP) vaccines in a timely manner. Whooping cough, or pertussis, is still around, and it can be devastating to infants, especially those less than 6 months of age. They need to be protected on schedule. Haemophilus influenzae type B (Hib) and pneumococcal conjugate vaccine (PCV) are also important for infants, considering that they successfully prevent the most common causes of bacterial meningitis.
- Influenza vaccine is also important for children to receive, especially those 6 months to 5 years of age. Many parents understand that influenza may be serious or even deadly for the elderly. But they often don't appreciate that morbidity from influenza among children less than 5 years of age is comparable to the elderly.
- For adolescents, it's a good idea to make sure that they are caught up for all the recommended vaccines. There's now a whooping cough booster (Tdap) recommended at 11-12 years of age. Meningococcal vaccine is recommended at this age as well, protecting against some of the most common causes of meningitis. Girls at this age should receive the (papillovirus) HPV vaccine, to decrease their risk of cancer later in life. And all children 6 months to 18 years of age are recommended to receive influenza vaccine yearly.
Types of vaccines
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 is no scientific evidence that vaccines "overwhelm the immune system," cause autism, or other unfounded allegations. These issues have been studied extensively.