©January 2009

During immunization campaigns, photos often depict unhappy children sitting obediently on the laps of parents looking reassuring and responsible.  These images often give us a sense that vaccinations are something we impose on those under our charge, such as our children, our pets or our ranch stock.  After emerging from adolescence, adults enjoy a sense of freedom from the need to subject themselves to the indignity of immunizations, similar to the assurance that their last SAT tests are behind them.  This is a fantasy.  The first clue comes in the form of the recommended annual influenza vaccinations for adults, but a growing number of additional vaccinations are available which are also important for adults to include in their health care planning.

First, it is worthwhile to review the theory behind vaccinations.  The immune system is assigned the job of protecting our body from foreign invasion.  It is unfortunate that students learn about the digestive, circulatory and nervous systems in fourth grade, but the immune system does not often show up in text books until later.  Like the heart, it works 24 hours a day, 365 days a year, except leap years, to prevent a virtually endless list of villains from causing infections.

The immune system learns to recognize these villains through experience.  Vaccinations provide this experience, either by giving our immune systems a sniff of dead fragments of viruses or bacteria (“inactivated” vaccines), or by giving our immune systems experience with a living distant cousin of the villainous germs (“live” vaccines) so that our body’s law enforcement can recognize the nasty ones when and if they show up.

Public Health experts have noted that there is indeed a tendency for populations with higher annual influenza vaccination rates to develop an increasing resistance to influenza penetration.  In other words, there appears to be some benefit to groups of people from prior years’ influenza vaccinations.  Nevertheless, because of the slippery behavior of this particular virus, repeat annual influenza vaccinations are still the recommended rule.

Some people confuse the influenza vaccine and the so-called “pneumonia” vaccine.  There is a bacteria called the “pneumococcus” which causes a dangerous form of pneumonia (lung infection), particularly in seniors who are disabled by other conditions of older age.  Infection from this bacteria can be prevented with the “pneumococcal vaccine,” AKA the “pneumonia vaccine.”  It is generally recommended that seniors 65 years of age and older receive two pneumonia vaccines one year apart.

Any adult who seeks emergency care for a cut or puncture wound is familiar with the question, “When was your last tetanus shot?”  A wound should always be washed with soap and water.  But if a person suffers a dirty wound, like a pitchfork to the foot or a barbed wire puncture in a field, a tetanus vaccination should have been obtained within the last five years.  If the wound is relatively clean, like a cut while washing dishes, then an interval of ten years is usually satisfactory.

If a person 11 years or older has never had a booster dose of tetanus that included inactivated pertussis vaccine, then the next tetanus shot should include the pertussis booster, in a shot called the “Tdap.”  This is because we have learned that immunity to pertussis (whooping cough) begins to disappear during adulthood.  We have learned this by experience.

The Human Papilloma Virus (HPV) causes cervical cancer.  About 12,000 women develop invasive cervical cancer each year in the U.S. and approximately one third will die of this disease.  The HPV vaccine is the first vaccine developed to prevent cancer.  It should be given in two doses if the patient’s first dose is given between 9 and 14 years of age, but if the patient is 15 to 26 years of age, then three doses are recommended.  There has been over a 60% drop in vaccine-type HPV infections in teen girls in the U.S. since the HPV vaccine was first released in 2006.

The varicella vaccine is used to prevent chicken pox in those who have never had the illness.  In seniors, the varicella virus that causes chicken pox can return from hiding within our own bodies and show up as a disease called “shingles” or “Herpes Zoster.”  This disease can be very painful and result in disabling symptoms.  Therefore, a shingles vaccine should be obtained by seniors 60 years and older as two doses of Shingrix, a new Zoster vaccine, 2 to 6 months apart.

Finally, the Measles, Mumps and Rubella vaccine should be obtained at least once during adulthood before age 50 to assure protection against these viral illnesses.

Keeping this information straight becomes ever more difficult as new vaccines are developed to protect us from the nefarious interests of unfriendly viruses and bacteria.  One of the most important responsibilities of public health is to help keep this information at your fingertips.

©February 2011

In the 50s, 60s and 70s, the greatest obstacle to the distribution of vaccine to the general population was access to clinical care.  For a large proportion of the U.S. population, understanding the benefits of polio and measles immunization, transportation to a clinic site to receive the vaccine and coverage of the cost of vaccination was beyond reach of the poor.  During that era, much of the adult population had already developed natural immunity to these conditions due to prior infections or earlier vaccination campaigns, so the illnesses tended to specifically target the young.  Therefore, a strategy was implemented to conduct vaccination clinics at schools, since these were sites that were universally attended by children.  The outcome was a public health triumph.  Polio was eliminated from North America and measles, which in 1920 caused 469,924 infections and 7,575 deaths, was declared eradicated from the United States in 2000.  Today, cases and clusters of measles that occur in the U.S. are imported from outside the country.

In 1910, Dr. William Osler expressed his concern for a segment of the population who opposed the use of vaccinations.  At that time, there was a considerable movement against the use of the cow pox vaccine that was being distributed to quell widespread outbreaks of smallpox.  Today, opposition to vaccination continues to be an issue.  While questioning and researching recommendations for maintaining one’s health and the health of one’s family is admirable, an unfortunately large number of unreliable sources of information are now readily available to confuse the picture.  Political turmoil in Pakistan has caused populations to be suspicious that the polio vaccination campaign is a political plot, hobbling efforts to eradicate polio in that country, one of only three in the world in which polio remains endemic.  We should inquire about the risks and benefits of vaccine, but we should be careful not to make decisions about whether to participate based upon personal convictions that may not be based upon good science.

The science tells us that in nearly every case, it is much safer for a person to receive the whooping cough vaccine during infancy and booster vaccines during childhood, also known as “Tdap,” than it is for us to live in a community that remains unvaccinated.  This is well documented by multiple studies conducted by the National Institute of Health, observational studies in the United Kingdom, and confirmed by a study done in British Columbia.  For those extremely rare cases in which a person has experienced a prior untoward reaction to a similar vaccination, your healthcare provider can confirm a medical exemption to assure that such a person does not receive the vaccine.  In such rare cases involving students, the medical provider must sign a Permanent Medical Exemption form to allow the child to attend school.

The need for a Permanent Medical Exemption from any particular vaccine is such a rare condition that communities will easily be able to vaccinate enough of the population to limit the ability of virtually all vaccine preventable diseases from gaining the advantage during an outbreak, as long as those capable of receiving the vaccine do so.  This number – the percent of the population that must be fully vaccinated against a particular infectious disease in order to prevent it from spreading through a community – is different for different diseases.  When this percent of the population is vaccinated, the population is said to have achieved “herd immunity.”  The following is a brief explanation of why achieving herd immunity works.

Imagine that you are a firefighter and it is your job to prevent a community from being burned up in the event that a lightning storm causes a wildfire.  When you look at the record, you notice that one neighboring community has never burned in the forested region around you, and another community has burned to the ground nearly every ten years.  As you look more closely, you learn that the community that has never burned has carefully trimmed underbrush, burned grassland every year to prevent it from growing tall, and has kept a small strip of land clear of trees surrounding the town, thereby preventing wildfires from entering the town and getting out of control by moving from tree to tree and bush to bush.  The community that has frequently burned has not done so.

This is the same strategy used by vaccinating communities to prevent outbreaks of disease.  As long as enough people are vaccinated to prevent the “wildfire” of disease from moving from person to person, the illness will not have enough people who are not immune to the disease to sustain the spread of the epidemic.  How thoroughly a community must trim the thick forest and underbrush to prevent wildfire depends upon the kinds of trees and the local weather, just like different infectious diseases require different levels of immunity in a community in order for the community to achieve herd immunity.