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AVAC publishes the AIDS Vaccine Handbook, an overview of how vaccines work; the particular challenges facing scientists in developing an AIDS vaccine; how clinical trials work; and how the research affects HIV-positive populations around the world. AVAC also sponsors the AIDS Vaccine Clearinghouse, a gateway to information about vaccine research, development and advocacy.
This site contains a comprehensive section for families including how vaccines work, safety and effectiveness of vaccines, frequently asked questions, vaccine misconceptions, etc.
The CDC website offers extensive information, from recommendations for particular vaccines to general discussions of vaccine safety and effectiveness. Of particular interest: General vaccine information: Information about Information about Influenza: International Travel Information:
CBER is responsible for ensuring the safety and efficacy of blood and blood products, vaccines, allergenics, and biological therapeutics. This site has a section that includes information about vaccines for kids, flu vaccines, and frequently asked questions.
This site provides pertinent information about childhood, adolescent, and adult immunizations. You will find publications and reports on vaccine preventable diseases, vaccine safety, vaccine coverage, immunization laws, and immunization registries.
This site Vaccine Adverse Event Reporting System is a cooperative program for vaccine safety of the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). VAERS is a post-marketing safety surveillance program, collecting information about adverse events (possible side effects) that occur after the administration of US licensed vaccines. This Web site provides a nationwide mechanism by which adverse events following immunization (AEFI) may be reported, analyzed and made available to the public. It also provides a vehicle for disseminating vaccine safety-related information to parents/guardians, healthcare providers, vaccine manufacturers, state vaccine programs, and other constituencies., a site dedicated to connecting prospective nurse practitioner students to accredited online degree programs. We provide everything you need to find a degree program that meets your career and professional goals.
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Vaccines (transcript)

While there is no question that vaccines work and have changed our world by eradicating deadly diseases, some people have concerns about the risks of immunizations.  The vaccine controversy remains-where do the rights of the public and the rights of the individual collide?

The development of vaccines may be the second most important public health intervention in history (safe drinking water being the first).  Vaccines have saved millions of lives over the years and prevented hundreds of millions of cases of disease.

Before vaccines:

• Smallpox was one of the most devastating diseases the world had ever known, killing millions of people worldwide.  The last person to get a natural case of smallpox was a 23-year-old cook in Somalia, in 1977.

• At one time, diphtheria killed more than 10,000 people a year and was one of the most common causes of death in school-aged children in the U. S. Today, most doctors will never see a single case of diphtheria, much less have a patient die from it.

• Polio paralyzed children by the thousands in the mid 20th century. There has not been a case of wild virus polio in the U. S. since 1979.

• Rubella (German measles) used to cause birth defects and mental retardation in thousands of newborns.

• Measles once infected millions of children, killing some. In 1962, the year before the measles vaccine was introduced, almost 500,000 cases of measles were reported in the U.S. However, after the measles vaccine became available, the number of measles cases dropped by 99 percent.

• Haemophilus influenzae type b (Hib) used to cause meningitis in thousands of children, leaving many with permanent brain damage.

• Pertussis (whooping cough) used to kill thousands of infants.

Vaccines are one of the most effective weapons we have against disease – on average they work in 85% to 99% of cases.  That's why children attending school in all 50 states of the U.S. are required to get certain immunizations (the specific requirements vary from state to state as well as the ability to seek exemptions from them)  They've been widely studied and have been proven to be safe and effective for most people.  

When people opt out of getting vaccinated, it puts us all at risk.  With the exception of smallpox, which vaccines eliminated from humans, these diseases are still out there.   The Centers for Disease Control and Prevention (CDC) experts say measles, mumps, rubella, and other vaccine-preventable diseases are still only at bay, awaiting a window of opportunity to reclaim prominence as common diseases.  In 1996, diphtheria appeared to be circulating in Alaska, Arizona, Montana, New Mexico, South Dakota and Washington State.  Cases of pertussis (whooping cough) more than tripled in the United States between 2001 and 2004, and this year (2008) there were outbreaks of measles in Arizona, New York, Michigan and Wisconsin.  History has clearly shown that when the rate of vaccination decreases, the incidence of the disease increases.

Some people question the necessity and safety of vaccines. 

• Since many diseases have virtually disappeared in the U.S., it's easy to become complacent.  The truth is, because millions of people travel to and from other countries where many vaccine-preventable diseases remain relatively common, these diseases could return to the U.S.

• Some believe vaccines may cause diseases such as autism, hyperactivity, developmental delay, attention deficit disorder, diabetes, multiple sclerosis, and sudden infant death syndrome (SIDS) among others.  The CDC has done extensive studies on these associations and in the past has reported there was no link.  However, a recent report  delivered to the House Appropriations Committee from CDC director Dr Julie Gerberding reveals that the data and methodology that the CDC used in its 2003 study, which evaluated the link between mercury in vaccines and autism and other disorders, was flawed.  This report was in response to the National Institute of Environmental Health Sciences (NIEHS) report that evaluated the strengths and weaknesses of the CDC's vaccine database.  The NIEHS panel had "identified several areas of weaknesses that when taken together reduce the usefulness of the project for conducting an ecologic study design to address the potential association between exposure to thimerosal and the risk of autism.".   What does all this mean?  While the CDC needs to go back and look at their data, the conclusion of vaccine safety has not been invalidated.  Regardless of the fact that no unreasonable harm has been proven by research thus far, some individuals will remain passionate about their opinions and will continue to question the link between vaccines and certain diseases.  Find out more about this subject by reading Key Point 2.

 [1] The Huffington Post, CDC:  Vaccine StudyUsed Flawed Methods by David Kirby, June 21, 2008.


Quick Facts

• Vaccines are one of the most successful medical advances of all time.

• Vaccine-preventable diseases still exist even though many young parents today have never seen a case, due to the success of the nation's current immunization program.

• Many vaccine-preventable diseases can have dangerous consequences, including seizures, brain damage, blindness, and even death.

• In order for vaccines to protect everyone, an estimated 85 to 95 percent of the population must be immunized.

• A substantial number of people in the U. S. still aren't adequately protected from vaccine-preventable diseases.  This includes children, even though those attending school in all 50 states of the U.S. are required to get certain immunizations.

• If vaccinations were stopped, each year about 2.7 million deaths worldwide from measles alone could be expected.

• Polio paralyzed American children by the thousands in the mid 20th century. There has not been a case of wild virus polio in the U. S. since 1979, but it would only take one case of polio from another country to bring the disease back to the U.S.

• Serious events occur more often from the actual infection or disease, rather than from the vaccine; therefore, the vaccine is much safer.

• On average vaccines work in 85% to 99% of cases. 

• Vaccines have been widely studied and have been proven to be safe and effective for most people. 

• The term "conscientious objector" originally referred to opponents of England's coercive smallpox vaccine campaign in the late nineteenth century.  Due to the success of worldwide vaccination for smallpox, that disease is the only one considered to have been eradicated from the earth.  The last person in the world to get a natural case of smallpox was a 23-year-old cook in Somalia, in 1977.

• Some believe vaccines may cause diseases such as autism, hyperactivity, developmental delay, attention deficit disorder, diabetes, multiple sclerosis, and sudden infant death syndrome (SIDS) among others.  However, scientists have run extensive studies on all of these potential associations and determined no connections exist.  


Ask Your Doctor

This list of questions is a good starting point for discussion with your doctor; however, it is not a comprehensive list.

• What vaccines does my child need?
• What vaccinations will be required by my child's school?

• What vaccines do I need?

• Can vaccines be administered if the person is sick, such as with a cold?

• Should I get a vaccine if I'm pregnant or trying to get pregnant?

• Should my child get multiple vaccinations at one time or should we spread them out?

• What are the risks associated with this particular vaccine versus risks for the disease?

• What are the pros and cons of having my child vaccinated if he or she has allergies to components of the vaccine?

• What vaccine side effects should I look out for?

• Do you send reminders out about boosters or other vaccinations?

Key Point 1

Vaccines work.  No matter what you think of the risks of vaccines, they have wiped out deadly diseases by stimulating the body's immune system to recognize bacteria and viruses and stop them. 

Vaccines have a remarkable track record. According to the U. S. Centers for Disease Control and Prevention (CDC) most vaccine-preventable diseases is at an all-time low in the U.S.  Hospitalizations and deaths from vaccine-preventable diseases have also shown striking decreases. 

  • Smallpox  was globally eradicated by 1980.


  • In 2004 (the last year data was published) there were no deaths from diphtheria, measles, mumps, polio, and rubella (German measles) in the United States .


  • There were no cases of diphtheria and polio in the U.S. in 2006.  Overall, incidence of measles has declined 99.9 percent, mumps by 95.9 percent, and rubella by 99.9 percent.


  • Deaths reported at peak for pertussis (whooping cough) was 7,518 in 1938, as opposed to 27 in 2006.


  • Haemophilus influenzae type b (Hib) meningitis once killed 600 children a year in the U.S., and left many of those who survived deaf, mentally disabled, or susceptible to seizures. Since the introduction of the Hib vaccine in 1987, the incidence of Hib has declined by 98 percent.


  • Incidence of tetanus has declined 92.9 percent, hepatitis A by 87.0 percent, hepatitis B by 80.1 percent, invasive pneumococcal disease by 34 percent and varicella (chickenpox) by 85 percent. 


  • Between 2001 and 2006, 170,000 cases and 9,800 deaths were prevented as a result of a new pneumococcal vaccine, known as PCV7 and approved in 2000 for young children.


  • In years when the vaccine and circulating viruses are well-matched, influenza vaccines have reduced laboratory-confirmed influenza by approximately 70% to 90% in healthy adults less than 65 years of age (percentages are lower for those with compromised immune systems).  Because influenza viruses change from year to year, new vaccines must also be formulated each year.  

How Your Immune System Works 
Disease-causing organisms (germs) contain complex molecules, called antigens, which stimulate your immune system to produce opposing proteins, called antibodies, and other protective responses. Antibodies bind to the germs, interfering with their function and making them susceptible to attack. When these antibodies can't act fast enough to keep you from being sick, they do help you get well. Simultaneously, they produce memory cells that protect against subsequent infections of the same germ.  You become immune – sometimes for awhile; sometimes for a lifetime. The drawback – you have to get sick before you become immune.  Enter vaccines.

How Vaccines Work
Vaccines help you develop immunity without having to get sick first.  They are introduced into your body, usually by injection, causing your immune system to react the same as it would if it were being invaded by the disease.

Scientists create an organism that can't cause full blown disease but still retains the antigens responsible for inducing an immune response.  They may use:

  • An organism that's similar to the virulent organism but that doesn't cause serious disease (such as Edward Jenner did with his use of the relatively mild cowpox virus to protect against the similar, but often lethal, smallpox virus). A recent example of this type of vaccine is the BCG vaccine used to protect against Mycobacterium tuberculosis. Weakened virus strains (called attenuated vaccines include Measles, mumps, and rubella vaccinations and Varicella vaccine.  
  • A dead / inactivated strain of the virus or bacteria (called killed vaccines). Injected polio and typhoid vaccines use dead cells.

• Parts of the viruses or bacteria (called component vaccines, acellular vaccines and subunit vaccines).  Sometimes these components are modified to improve the immune response. Examples of component vaccines are:
      o Haemophilus influenzae type b (Hib) vaccine
      o Hepatitis A (Hep A) vaccine
      o Hepatitis B (Hep B) vaccine
      o Pneumoccocal conjugate vaccine

  • The poisons produced by germs can be inactivated to form toxoid vaccines.  The poisons are treated with heat or chemicals to destroy their ability to cause illness. Diphtheria and tetanus are examples of toxoid vaccines.

Although some vaccines can give you immunity after a single dose no matter when you receive it, others have to be given several times at certain ages and intervals to provide full protection.
Neither killed nor component vaccines generally induce the strongest immune responses and may require a "booster" every few years to insure their continued effectiveness.  They are the safest vaccines for immunocompromised patients.  Weakened live cell (attenuated) vaccines are often the most successful vaccines. However, these also carry the greatest risk because they could potentially cause more severe disease in some people or mutate back to the virulent form.  They are not recommended for use in immunocompromised patients. Immunity is often lifelong with attenuated vaccines and doesn't require booster shots. Toxoid vaccines often require a booster every ten years.  Diseases that change, such as the flu, need a new vaccine every year to fit the current strain.


Key Point 2

Vaccines have protected entire populations and generations from some horrific diseases.  However, there are individual cases where vaccines don't work or do harm.   

Vaccines play a crucial role in keeping us healthy; however, they are not a 100 percent guarantee against disease.  

  • An individual may not respond to certain vaccines (the measles vaccine fails to produce immunity in about 1 percent of the people who get it as recommended).
  • Some people get diseases they were vaccinated against because they fail to get booster shots.
  • Vaccines made from weakened (attenuated) live viruses may cause very mild symptoms of the disease itself.  The only routine vaccines that currently use weakened live virus are the chicken pox (varicella), measles-mumps-rubella (MMR), nasal spray flu, and rotavirus vaccines. The risk of disease from vaccination with attenuated viruses is extremely small, and it's impossible to get the disease from any vaccine made with dead (killed) bacteria, or viruses or just part of a bacteria or virus.  Risk is greatest with chicken pox, but symptoms are much milder than getting the disease itself.  Vaccinated children who get chicken pox tend to get fewer than 25 blisters. By contrast, unvaccinated children can develop more than 500 blisters.  

Like any medicine, vaccines do sometimes cause reactions. These are usually mild local reactions (soreness or redness where the shot is given) or a low-grade fever and are short-lived.

More serious reactions are much less common, and include severe allergy to a component of a vaccine such as eggs, baker's yeast or gelatin. Anaphylaxis (an immediate and severe allergic reaction that can cause breathing difficulties, a drop in blood pressure and loss of consciousness) is rare. Based on the last 5 years of complete national data, the annual rate of anaphylaxis ranges from 0.11 to 0.31 reports per 100,000 doses of vaccines distributed.  Doctors screen for known allergies prior to immunizations and generally keep people under supervision for at least 15 minutes following immunization.  Your doctor can help you understand your particular risk and if the benefit of receiving the vaccine outweighs the risks.  It's possible to give the vaccine in small amounts over many hours, while closely monitoring for an allergic reaction. 

Every physician is mandated to report adverse effects of vaccines to the Vaccine Adverse Event Reporting System (VAERS) so that the event may be studied further.  Any adverse effects are acted upon immediately when there appears to be an association.  The VAERS Web site is available at:

Vaccine myths, many of which circulate on the Internet, exist in abundance.  These myths link vaccines to a multitude of problems, but to date, studies have found no connection between them.

  • AutismStudies involving tens of thousands of children, comparing the incidence of autism among children who received the measles-mumps-rubella (MMR) vaccine and those who didn't, have clearly shown that MMR does not cause autism. A 2004 report from the Institute of Medicine (IOM) found that thimerosal does not cause autism. 
  • Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD):  Thimerosal, the mercury-based preservative used in some vaccines before 2001, has come under suspicion of contributing to the rise of ADD and ADHD. Three studies found that thimerosal in vaccines did not cause developmental or psychological problems. Furthermore, discontinuing the use of thimerosal in vaccines has not reduced the incidence of ADD or ADHD.
  • Asthma:  Scientists say there's little evidence of a link between vaccines and asthma or allergies.  Large studies have found:
    • No increased risk of developing childhood asthma associated with the DPT (diphtheria, tetanus, and whole cell pertussis) vaccine, the MMR (measles, mumps, and rubella) vaccine, or the oral polio vaccine.
    • Immunizations received before 18 months of age are not related to asthma in later childhood.
  • Bowel obstruction:   In the late 1990s a different type of rotavirus vaccine was briefly available. It was taken off the market in 1999 because it was linked to an increased risk for intussusception (a rare type of bowel obstruction) in young infants. The new, different rotavirus vaccine, called RotaTeq, has been studied in more than 70,000 children and has not been found to have this increased risk. Millions of doses have been used successfully since the vaccine was licensed.
  • Diabetes:  A study published in 2001 looked at whether the timing of childhood vaccinations is related to the risk of a child getting diabetes. This study, which examined data from 1,020 children in the U.S., showed no association between any of the recommended childhood vaccines and diabetes, regardless of when the vaccines were given. 
  • SIDS:  Since 1999, parents have worried about a connection between the hepatitis B vaccine and sudden infant death syndrome (SIDS) when an ABC 20/20 program aired a report suggesting such an association. Experts have examined the claim and determined that the deaths were not linked to the vaccine. In fact, ever since the vaccine was recommended for all infants in 1991, the incidence of SIDS has fallen.
  • Multiple sclerosis(MS):  A number of excellent, well-controlled studies have compared the incidence of MS among those who have been vaccinated against hepatitis B and those who haven't and have concluded that the vaccine doesn't cause multiple sclerosis or worsen the symptoms in those who already have the disease.  Also, since widespread use of the hepatitis B vaccine began in the early 1990s, rates of MS and other autoimmune diseases have not gone up.

New vaccines go through a rigorous process before being licensed. The U.S. Food and Drug Administration's (FDA) Center for Biologics Evaluation and Research (CBER) coordinates the process with involvement from:

  • The Advisory Committee on Immunization Practices (ACIP) at the CDC;
  • The Committee of Infectious Diseases (COID) at the American Academy of Pediatrics; and
  • The American Academy of Family Physicians (AAFP).

They're licensed only after thorough laboratory studies and clinical trials are conducted.   After introduction, they continue to be monitored, studied and improved.

If you have concerns or want to take an approach that varies from the recommended vaccination schedule, talk to your doctor.   Not vaccinating against certain diseases means substituting one type of risk for another.  You need to understand the ramifications of your decision.  

The U.S. Food and Drug Administration recommend these steps:

  • Review vaccine information sheets that explain the potential risks of each vaccine. Health practitioners are required by law to provide them.
  • Talk to your doctor about whether certain reactions to vaccines can be controlled. For example, fever may be prevented or reduced by taking acetaminophen before or after vaccination.
  • Tell your doctor if you, your child, or a sibling has ever had a bad reaction to a vaccine.
  • Ask your doctor about conditions under which you or your child should not be vaccinated. This might include being sick or having a history of certain allergic or other adverse reactions to previous vaccinations or their components, such as allergies to eggs, which are used to grow influenza vaccines.
  • Report unexpected events after vaccinations to your doctor and to the Vaccine Adverse Event Reporting System (VAERS) at 1-800-822-7967.

Key Point 3

Vaccine policy, like other public policy, is a balance between personal rights and individual and societal protection.

Fifty years ago, measles was one of the most common childhood diseases in the U.S. – virtually every child got it. Today it's almost non-existent in the US.  We can thank our country's high childhood immunization coverage levels for that and for the low incidence of other highly contagious and potentially lethal diseases, like mumps, chicken pox and whooping cough.   

Because we don't see these diseases every day, the world might seem a lot safer than in the past.  But consider this.  Even if the risk of getting these diseases is low, it's not zero.  And, it just takes one person to start the spread of a disease.  A single case remains a single case only if everyone around the infected person is immune. If they're not, that single case can easily become an epidemic.

The way to prevent disease in communities is to create "herd immunity."  Herd immunity works by decreasing the numbers of susceptible (non-immune) people. When the number of susceptible people drops low enough, the catch-and-infect cycle stops dead in its tracks.  The greater the proportion of vaccinated members of the community, the more quickly this happens.

Without the protection afforded by a highly-immunized population, almost any disease can make a comeback.  While rare, many of these diseases still circulate in this country and exist in even greater numbers in other parts of the world. 

Recently, a surge of negative publicity has focused on unsubstantiated risks of vaccines, and some people are opting out of important vaccinations (see Key Point 2 to read about vaccine myths.)  While public schools and most private schools require proof of vaccination, parents can seek exemptions from these requirements.  Exemptions may be for medical, religious, or philosophical reasons and vary by state.

The decision to refuse immunization has both personal and societal consequences. 

First and foremost vaccines save lives.  According to a Washington state-based organization called Parents of Kids with Infectious Diseases (PKIDS), some parents are shocked to learn that both children and adults can die of vaccine-preventable diseases they hadn't considered a threat.

Secondly, illness is expensive.  Costs can be measured in lost productivity, expensive treatments, hospitalizations, and permanent disabilities.  It's been estimated that for every $1 we spend on vaccinations, we save $10 in later health care costs (National Academy of Sciences).

According to the CDC, the growing number of personal exemptors presents a very real danger. There have been several studies now that have looked at the association between exemption rates and disease rates, and it turns out that the more exemptors you have, the more disease you have. There's plenty of precedent to support that stance.  For example:

  • When measles vaccination rates in the U.S. dropped in the late 1980s, more than 100,000 people came down with the disease and 120 died from it. In 1998, when immunization rates were back up, only 89 people became sick from measles and no one died.
  • During the 1990s, the number of reported whooping cough cases among adolescents and adults more than doubled in the United States, largely because many people didn't receive booster shots to extend their immunity.
  • In the former Soviet Union, a drop in childhood immunization rates and adult booster shots led to a major epidemic of diphtheria between 1990 and 1999.  There were more than 150,000 cases and 5,000 deaths from this once rare disease.
  • In 1974, about 80 percent of Japanese children were being vaccinated against pertussis (whooping cough).  That year Japan had only 393 pertussis cases and no deaths.  Then the vaccination rate dropped to about 10 percent.  By 1979 the country was hit with a major pertussis epidemic with more than 13,000 cases and 41 deaths.  When routine vaccination was reinstated, disease rates dropped again. 

Where do individual rights end and the rights of the public begin? In an increasingly global neighborhood, disease prevention is not just about the individual.  Yes, it's true that a single individual's chance of catching a disease is low if everyone else is immunized.  But if too many individuals take this approach, herd immunity breaks down. Some people can't get certain vaccines for medical reasons and some don't respond to them as expected. For those individuals, the immunity of people around them is their only protection.  In order for vaccines to protect everyone, an estimated 85 to 95 percent of the population must be immunized.  

Children stand to benefit the most from vaccines, as they're often the most vulnerable to disease and the least likely to have been previously exposed to infection. That's why 80 percent of all shots are due within the first two years of life.  As children move into adolescence, protection provided by some childhood vaccines can begin to wear off.  Also, they're at greater risk of catching certain diseases, like meningitis and HPV.

Of course, immunization isn't just for kids.  Vaccine-preventable diseases pose serious dangers to adults, with more than 30,000 deaths each year.  A Centers for Disease Control and Prevention survey reports that only 2 percent of adults are currently protected against shingles, tetanus, diphtheria and whooping cough. Every year more than half of adults at high risk of influenza complications seek some type of medical treatment, but they fail to receive influenza vaccine.  Pneumonia cases are on the rise, especially among seniors.

Without vaccine protection, we can easily contract and transmit infectious diseases. You need to know what vaccines are due and at what age.  Your doctor can tell you or you can get the information at the following links.

When is it safe to stop vaccinations for a disease?  The answer:  When that disease has been eradicated worldwide.


Medline Plus

Medline Description: 

Conduct an off-site search for Vaccines information from MedlinePlus.  These up-to-date search results are based on search terms specific to Second Opinion Key Points.

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