Immunization, or vaccination, is the process or procedure by which a person is rendered immune, or resistant, to a specific disease. A vaccine is a biologically active substance designed to protect children and adults from infections caused by bacteria and viruses. Vaccines also are called immunizations because they take advantage of our natural immune system’s ability to prevent infectious illness. To understand how vaccines work, we need to consider how our immune system protects us from infections.
The Immune System
Our bodies are armed with a variety of methods to protect against infectious microorganisms like bacteria and viruses. The most sophisticated of these methods activate specific immune system cells, some of which make proteins called antibodies. For the immune system to respond to an infectious microorganism, the invader must carry identifying markers, called antigens, that the immune cells recognize. Both bacteria and viruses carry their own antigens. Immune cells are able to recognize these highly specific antigens, identify them as threatening, and respond accordingly.
Consider the example of chickenpox (varicella), a common viral infection. Those born prior to the early 1990s, when the varicella vaccine was first introduced, probably remember staying home from school for about a week with a fever and rash. They probably also noticed that the same illness never reoccurred. This is true even though they have almost certainly been exposed to the virus many times since. The immune system successfully remembers the chickenpox antigen from its initial encounter with the virus and reliably responds each time it is confronted with the identical antigen on the single strain of varicella that infects humans.
Now consider the flu. Why is it possible, even likely, to suffer from the flu winter after winter despite a healthy immune response every time? Well, unlike the varicella virus, different strains of influenza infect people each season. Being immune to last year’s flu strain may protect you for the duration of the season, but it will be of little use when next year’s strains come around.
Vaccines to Prevent Other Diseases
All vaccines are designed to target infections, but two commonly recommended vaccines have the added benefit of protecting against cancer. This is true because of the close association of certain viruses with the development of certain cancers. Hepatitis B is the first example of a vaccine that also reduces the risk of cancer. Hepatitis B is a major cause of liver cancer. By eliminating the risk of hepatitis B, the vaccine protects against its associated cancer.
A more recent example of an anticancer immunization is the human papillomavirus (HPV) vaccine, introduced in 2006. Since HPV is the leading cause of cervical cancer, immunized women should experience a lower risk of Pap smear abnormalities, including pre-cancers (cervical dysplasia) and cancer. In males, different types of HPV can cause genital warts. Others types can cause cancers in the penis, anus, and back of the mouth and throat. Based on a number of studies documenting the vaccine’s effectiveness, the US Centers for Disease Control and Prevention (CDC) currently recommends that all boys and girls aged 11-12 years receive the 3-dose vaccination.
Why Should Everyone Be Vaccinated?
Imagine for a moment a disease contracted every year by more than 50 million people worldwide. Thirty percent die of this disease and the majority of those that survive are left with disfiguring skin lesions, most often on the face, rendered totally blind, or both. Now imagine this same disease, which has been in existence for at least 3,000 years, being completely eliminated from the face of the earth in as few as 25 years—from over 50 million to not a single case anywhere. What medical advancement could possibly be that powerful? The smallpox vaccine.
The success rates of other vaccines are equally impressive. Where vaccines are readily available and routinely administered, the rates of measles, mumps, rubella, polio, hepatitis B, and many other infections have plummeted. In 1952, for example, there were 21,000 cases of polio resulting in paralysis in the US. By 1980, there were zero, and health officials are on the brink of worldwide polio eradication. Based on this tremendously successful track record, great efforts are made to ensure that every child is immunized against a constantly growing number of infections.
Despite the majority of children getting vaccinated, some children in the United States are still not immunized. This level of compliance is apparently sufficient to keep extremely rare infections from returning. However, parental choice to not vaccinate children has likely contributed to recent localized epidemics of measles and pertussis (whooping cough) infections. Consider the 2014-2015 outbreak of measles in the United States. Nearly all cases were linked to one person at an amusement park in California. It did not take long for over 120 cases to spread across the country.
How Safe Are Vaccines?
Childhood vaccines are generally very safe. In the United States, vaccines have resulted in record-low levels of certain childhood diseases. Vaccines not only protect the person they are given to, but also the population at large, since they work to reduce the general prevalence of once-common infections.
The small risk of serious adverse events is far outweighed by the disease-preventing benefits of vaccines in most cases. Some children may experience mild adverse events at the time of the vaccine, including fever, soreness at the vaccine site, or a lump under the skin where the shot was given. Some reactions (MMR) will not appear until weeks after the vaccine is given. Those who choose not to have their child vaccinated because of
There are some situations, though, in which children should not receive certain vaccines. Examples of these situations include children who:
- Had a life-threatening allergic reaction to a component in the vaccine
- Are severely ill (wait until the child has recovered)
- Are taking medications to suppress the immune system
- Have certain types of cancer or other diseases
For more information about immunizations, talk with your doctor. Casey Bowles, PA-C, is available to discuss immunizations and any questions you may have regarding their safety. To schedule an appointment, call the office at (540) 977-0900.
Source: Centers for Disease Control