Archive for January 13th, 2011


Thursday, January 13, 2011 // Uncategorized

Some people don’t want their children vaccinated against disease because of a fear that the vaccines might harm them.  This occurred even before the recent controversial link between MMR (measlesmumpsrubella) and autism.  Some schools allow for children to be admitted without immunizations due to religious objections.  the problem with this is that it puts other children at risk by reducing “herd immunity” and allowing diseases to be spread because fewer people have resistance to the disease.

Herd immunity (or community immunity) describes a form of immunity that occurs when the vaccination of a significant portion of a population (or herd) provides a measure of protection for individuals who have not developed immunity.[1] Herd immunity theory proposes that, in contagious diseases that are transmitted from individual to individual, chains of infection are likely to be disrupted when large numbers of a population are immune to the disease. The greater the proportion of individuals who are immune, the smaller the probability that a susceptible individual will come into contact with an infectious individual.[2]

Estimated Herd Immunity thresholds for vaccine preventable diseases[2]
Disease Transmission R0 Herd immunity threshold
Diphtheria Saliva 6-7 85%
Measles Airborne 12-18 83 – 94%
Mumps Airborne droplet 4-7 75 – 86%
Pertussis Airborne droplet 12-17 92 – 94%
Polio Fecal-oral route 5-7 80 – 86%
Rubella Airborne droplet 5-7 80 – 85%
Smallpox Social contact 6-7 83 – 85%
^ – R0 is the basic reproduction number, or the average number of secondary infectious cases that are produced by a single index case in completely susceptible population.

Vaccination acts as a sort of firebreak or firewall in the spread of the disease, slowing or preventing further transmission of the disease to others.[3] Unvaccinated individuals are indirectly protected by vaccinated individuals, as the latter will not contract and transmit the disease between infected and susceptible individuals.[2] Hence, a public health policy of herd immunity may be used to reduce spread of an illness and provide a level of protection to a vulnerable, unvaccinated subgroup. Since only a small fraction of the population (or herd) can be left unvaccinated for this method to be effective, it is considered best left for those who cannot safely receive vaccines because of a medical condition such as an immune disorder or for organ transplant recipients.

The proportion of immune individuals in a population above which a disease may no longer persist is the herd immunity threshold. Its value varies with the virulence of the disease, the efficacy of the vaccine, and the contact parameter for the population.[3] No vaccine offers complete protection, but the spread of disease from person to person is much higher in those who remain unvaccinated.[4] It is the general aim of those involved in public health to establish herd immunity in most populations. Complications arise when widespread vaccination is not possible or when vaccines are rejected by a part of the population. As of 2009[update], herd immunity is compromised in some areas for some vaccine-preventable diseases, including pertussis and measles and mumps, in part because of parental refusal of vaccination.[5][6][7]

Herd immunity only applies to diseases that are contagious. It does not apply to diseases such as tetanus (which is infectious, but is not contagious), where the vaccine protects only the vaccinated person from disease.[8] Herd immunity should not be confused with contact immunity, a related concept wherein a vaccinated individual can ‘pass on’ the vaccine to another individual through contact.

Here’s an article from today’s New England of Journal which addresses the issue:

The Age-Old Struggle against the Antivaccinationists

Gregory A. Poland, M.D., and Robert M. Jacobson, M.D.

N Engl J Med 2011; 364:97-99January 13, 2011


Since the introduction of the first vaccine, there has been opposition to vaccination. In the 19th century, despite clear evidence of benefit, routine inoculation with cowpox to protect people against smallpox was hindered by a burgeoning antivaccination movement. The result was ongoing smallpox outbreaks and needless deaths. In 1910, Sir William Osler publicly expressed his frustration with the irrationality of the antivaccinationists by offering to take 10 vaccinated and 10 unvaccinated people with him into the next severe smallpox epidemic, to care for the latter when they inevitably succumbed to the disease, and ultimately to arrange for the funerals of those among them who would die (see the Medical Notes section of the Dec. 22, 1910, issue of the Journal). A century later, smallpox has been eradicated through vaccination, but we are still contending with antivaccinationists.

The Cow Pock — or — the Wonderful Effects of the New Inoculation.

Since the 18th century, fear and mistrust have arisen every time a new vaccine has been introduced. Antivaccine thinking receded in importance between the 1940s and the early 1980s because of three trends: a boom in vaccine science, discovery, and manufacture; public awareness of widespread outbreaks of infectious diseases (measles, mumps, rubella, pertussis, polio, and others) and the desire to protect children from these highly prevalent ills; and a baby boom, accompanied by increasing levels of education and wealth. These events led to public acceptance of vaccines and their use, which resulted in significant decreases in disease outbreaks, illnesses, and deaths. This golden age was relatively short-lived, however. With fewer highly visible outbreaks of infectious disease threatening the public, more vaccines being developed and added to the vaccine schedule, and the media permitting widespread dissemination of poor science and anecdotal claims of harm from vaccines, antivaccine thinking began flourishing once again in the 1970s.1

Little has changed since that time, although now the antivaccinationists’ media of choice are typically television and the Internet, including its social media outlets, which are used to sway public opinion and distract attention from scientific evidence. A 1982 television program on diphtheria–pertussis–tetanus (DPT) vaccination entitled “DPT: Vaccine Roulette” led to a national debate on the use of the vaccine, focused on a litany of unproven claims against it. Many countries dropped their programs of universal DPT vaccination in the face of public protests after a period in which pertussis had been well controlled through vaccination2 — the public had become complacent about the risks of the disease and focused on adverse events purportedly associated with vaccination. Countries that dropped routine pertussis vaccination in the 1970s and 1980s then suffered 10 to 100 times the pertussis incidence of countries that maintained high immunization rates; ultimately, the countries that had eliminated their pertussis vaccination programs reinstated them.2 In the United States, vaccine manufacturers faced an onslaught of lawsuits, which led the majority of them to cease vaccine production. These losses prompted the development of new programs, such as the Vaccine Injury Compensation Program (VICP), in an attempt to keep manufacturers in the U.S. market.

The 1998 publication of an article, recently retracted by the Lancet, by Wakefield et al.3 created a worldwide controversy over the measles–mumps–rubella (MMR) vaccine by claiming that it played a causative role in autism. This claim led to decreased use of MMR vaccine in Britain, Ireland, the United States, and other countries. Ireland, in particular, experienced measles outbreaks in which there were more than 300 cases, 100 hospitalizations, and 3 deaths.4

Today, the spectrum of antivaccinationists ranges from people who are simply ignorant about science (or “innumerate” — unable to understand and incorporate concepts of risk and probability into science-grounded decision making) to a radical fringe element who use deliberate mistruths, intimidation, falsified data, and threats of violence in efforts to prevent the use of vaccines and to silence critics. Antivaccinationists tend toward complete mistrust of government and manufacturers, conspiratorial thinking, denialism, low cognitive complexity in thinking patterns, reasoning flaws, and a habit of substituting emotional anecdotes for data.5 Their efforts have had disruptive and costly effects, including damage to individual and community well-being from outbreaks of previously controlled diseases, withdrawal of vaccine manufacturers from the market, compromising of national security (in the case of anthrax and smallpox vaccines), and lost productivity.2

The H1N1 influenza pandemic of 2009 and 2010 revealed a strong public fear of vaccination, stoked by antivaccinationists. In the United States, 70 million doses of vaccine were wasted, although there was no evidence of harm from vaccination. Meanwhile, even though more than a dozen studies have demonstrated an absence of harm from MMR vaccination, Wakefield and his supporters continue to steer the public away from the vaccine. As a result, a generation of parents and their children have grown up afraid of vaccines, and the resulting outbreaks of measles and mumps have damaged and destroyed young lives. The reemergence of other previously controlled diseases has led to hospitalizations, missed days of school and work, medical complications, societal disruptions, and deaths. The worst pertussis outbreaks in the past 50 years are now occurring in California, where 10 deaths have already been reported among infants and young children.

In the face of such a legacy, what can we do to hasten the funeral of antivaccination campaigns? First, we must continue to fund and publish high-quality studies to investigate concerns about vaccine safety. Second, we must maintain, if not improve, monitoring programs, such as the Vaccine Adverse Events Reporting System (VAERS) and the Clinical Immunization Safety Assessment Network, to ensure coverage of real but rare adverse events that may be related to vaccination, and we should expand the VAERS to make compensation available to anyone, regardless of age, who is legitimately injured by a vaccine. Third, we must teach health care professionals, parents, and patients how to counter antivaccinationists’ false and injurious claims. The scientific method must inform evidence-based decision making and a numerate society if good public policy decisions are to be made and the public health held safe. Syncretism between the scientific method and unorthodox medicine can be dangerous.

Fourth, we must enhance public education and public persuasion. Patients and parents are seeking to balance risks and benefits. This process must start with increasing scientific literacy at all levels of education. In addition, public–private partnerships of scientists and physicians could be developed to make accurate vaccine information accessible to the public in multiple languages, on a range of reading levels, and through various media. We must counter misinformation where it is transmitted and consider using legal remedies when appropriate.

The diseases that we now seek to prevent with vaccination pose far less risk to antivaccinationists than smallpox did through the early 1900s. Unfortunately, this means that they can continue to disseminate false science without much personal risk, while putting children, the elderly, and the frail in harm’s way. We can propose no Oslerian challenge to demonstrate our point but have instead a story of science and contrasting worldviews: on the one hand, a long history of stunning triumphs, such as the eradication of smallpox and control of many epidemic diseases that had previously maimed and killed millions of people; on the other hand, the reality that none of the antivaccinationists’ claims of widespread injury from vaccines have withstood the tests of time and science. We believe that antivaccinationists have done significant harm to the public health. Ultimately, society must recognize that science is not a democracy in which the side with the most votes or the loudest voices gets to decide what is right.

Disclosure forms provided by the authors are available with the full text of this article at

Source Information

From the Mayo Clinic Vaccine Research Group (G.A.P., R.M.J.), the Department of Medicine (G.A.P.), and the Department of Pediatric and Adolescent Medicine (G.A.P., R.M.J.), Mayo Clinic, Rochester, MN

Here is some information from UpToDate on the importance of vaccinations and their necessity.

Patient information: Why does my child need vaccines?
Last literature review version 18.3: September 2010 | This topic last updated: January 7, 2008 (More)

INTRODUCTION — Vaccines are one of the most effective ways to prevent serious illness in children and adults. Vaccine programs in the United States have been quite successful in reducing the number of children affected by many highly contagious diseases, including measles, rubella, mumps, diphtheria, and polio.

The following is a discussion of how immunizations work, common side effects, reasons to avoid a particular vaccine, and common concerns about vaccines. Separate articles discuss individual vaccines for children and adults. (See “Patient information: Vaccines for infants and children age 0 to 6 years” and “Patient information: Vaccines for children age 7 to 18 years” and “Patient information: Adult vaccines”.).

HOW DO VACCINES WORK? — The immune system functions to protect the body against illness and infection. When an organism (bacterium or virus) is foreign to the body, the immune system detects the organism and responds by creating proteins called antibodies. Antibodies fight the infection and help the person to recover.

Antibodies also work to prevent a person from becoming ill in the future. If a person is exposed to the organism again, the immune system recognizes it and rapidly produces more of the antibodies required to destroy the organism. This response protects the individual from developing the disease, ideally for life. For example, a person who had chickenpox as a child is unlikely to develop it again, even if he or she is in close contact with a person who is infected.

Vaccines work by stimulating the immune system to produce antibodies. However, unlike bacteria and viruses, vaccines do not cause the person to become ill in order to develop these antibodies. There are two main types of vaccines: active and passive.

Active vaccines — Active vaccines use a weakened form of the harmful bacteria or virus to stimulate the immune system.

Some bacteria (eg, diphtheria, tetanus) cause illness because they produce harmful substances called toxins. Vaccines that help the immune system protect the body from toxins are called toxoids. Toxoids are made from weakened forms of the bacterial toxins.

Passive vaccines — Passive vaccines provide temporary immunity using antibodies obtained from a large pool of donors; this type of preparation is known as immune serum globulin. Passive vaccines offer short-term protection to children or adults who have been exposed to a specific organism.

One example of a passive vaccine is hepatitis B immune globulin (HBIG). HBIG is given to newborns whose mothers test positive for hepatitis B surface antigen (HBsAg). HBIG provides temporary protection to the newborn against infection with hepatitis B.

Vaccines protect children and adults — Many parents are concerned about the risks of vaccines. However, vaccines have a long record of being a safe and effective way of preventing disease. In most cases, the benefits of vaccinating a child are far greater than the potential risks.

Diseases such as diphtheria and measles were common at one time in the United States, but are no longer a significant threat because of vaccination programs. However, these illnesses are still common in developing countries throughout the world. Because it is easy to travel from one country to another, it is easy for illness to spread from children or adults who are not vaccinated. Vaccination helps to reduce a child’s, family’s, and even an entire community’s chances of becoming ill by decreasing the number of people who get sick and transmit the infection to others. This process is sometimes referred to as “herd immunity.”

An example of a successful vaccination effort is the smallpox program. Before a vaccine was available, smallpox killed millions of people every year. Up until the early 1970s, smallpox disease was a worldwide threat to life. Use of the smallpox vaccine in large populations of people prior to the 1970s led to complete eradication of the disease and the smallpox vaccination is no longer required.

How are vaccines given? — In children, most immunizations are given in the form of a shot. Vaccines are also given in other ways, such as in a liquid taken by mouth (eg, rotavirus) or as a nasal spray (eg, one form of the influenza vaccine).

Paying for vaccines — Vaccines are available for every child in the United States, even for those who do not have health insurance. If a child does not have health insurance and the parents are unable to pay for vaccines, a program called Vaccines for Children is available. This program helps to cover the costs of vaccines given at private doctor’s offices, clinics, hospitals, community health clinics, and in some schools (

VACCINE SIDE EFFECTS — Most vaccines and toxoids are safe and cause few if any serious side effects. Very rarely, serious side effects do occur. Children who develop unusual reactions such as rashes involving much of the body surface, difficulty breathing, excessively high fevers, seizures or loss of consciousness within a short time after receiving a vaccine should be evaluated by a healthcare provider.

To report an unusual reaction after a vaccine, you can contact the national Vaccine Adverse Events Reporting System (VAERS,, telephone number 1-800-822-7967 begin_of_the_skype_highlighting              1-800-822-7967      end_of_the_skype_highlighting). Parents who are concerned about a particular vaccine should discuss their concerns with their child’s healthcare provider.

Mild side effects — Vaccines and toxoids can occasionally cause mild side effects, including:


  • A low-grade fever
  • A red and tender area at the site of an injection

    Moderate side effects — Occasionally, children can develop a combination of fever, skin rash, swollen lymph nodes, and/or joint pain after vaccination. These reactions, called serum sickness-like reactions, can be uncomfortable, although they are rarely dangerous and resolve without treatment in days to weeks.

    Severe side effects — Severe side effects of vaccines are rare, but may include a severe neurologic reaction (eg, seizures) or severe allergic reactions (eg, anaphylaxis). Allergic reactions usually occur within minutes to hours of receiving the vaccine. If this occurs in the doctor or nurse’s office, emergency care can be given immediately. If a severe reaction occurs later, the parent/guardian should call emergency medical services, available in most areas of the United States by calling 911.

    Reasons to avoid vaccination — A particular vaccine may not be recommended for children with a serious allergic reaction to the following:


  • Eggs or egg protein, since some vaccines are prepared with embryonic chicken eggs or cultures (eg, influenza vaccines, yellow fever vaccines). A mild allergic reaction to eggs does not mean that the vaccine should be avoided.
  • The antibiotic medications neomycin or streptomycin (some vaccines contains trace amounts of neomycin)
  • Gelatin
  • A specific vaccine in the past

    In some cases, parents may not know their child is allergic to one of these components until the vaccine is given and the child develops a reaction.

    In addition, live virus vaccines are generally not recommended for children with a weakened immune system since there is an increased risk of infection as a result of the vaccine. However, there may be exceptions to this recommendation.

    MMR and varicella vaccine should be delayed in children who have recently received a blood transfusion or blood products (eg, immunoglobulin preparations) since these products can make the vaccine less effective.

    Conditions that do not affect vaccination — The following conditions do not require delaying or avoiding vaccines:


  • Current or recent mild illness
  • Current or recent antibiotic therapy
  • Previous mild to moderate tenderness, redness, or swelling at the site of injection or fever less than 104.9ºF (40.5ºC) after a previous vaccination
  • A personal history of allergies, except those listed above
  • A family history of adverse reactions to vaccines

    Are vaccines safe for my child? — There have been concerns about the safety of vaccines for children. These concerns include use of the preservative thimerosal and the relationship between vaccines and autism.

    Thimerosal — Thimerosal is a derivative of mercury that was previously used as a preservative in most vaccines. As the number of vaccinations given to infants increased, there was concern that this preservative could lead to potentially unsafe levels of mercury levels in some infants. As a result, several expert groups recommended in 1999 that all standard childhood vaccines be produced without thimerosal.

    The recommendation was a precautionary change and was not based upon known harm from thimerosal. Thimerosal-free forms of all of the childhood vaccines are available in the United States.

    Vaccines and autism — A second concern was in regards to a possible relationship between certain vaccines and the subsequent development of autism. Despite this concern, there is no scientific evidence that receiving these vaccines causes or increases the risk of developing autism.

    Studies that raised this possibility had significant weaknesses in their design. Several of the studies were based on a small number of children and relied upon the memory of parents or pediatricians to recall when behavioral signs/symptoms related to autism began. Most studies did not include a control group to compare children who were vaccinated with those who were not vaccinated to determine if there was a cause and effect relationship. It was recently reported that some cases of autism are attributable to gene abnormalities.

    For more information about any potential link between vaccines and autism, visit the National Immunization Program Web site at

    VACCINE RECOMMENDATIONS — Children should begin receiving vaccines within the first few months of life. This allows the child to be protected from common childhood illnesses as well as illnesses that can develop during adulthood.

    Many diseases prevented by vaccines are more serious in young children. In addition, most infants visit a healthcare provider frequently during the first year, which improves the chances of completing most vaccines that require multiple doses. In most states, specific vaccines are required before the child can attend school. This policy is designed to not only protect the individual child but to prevent the spread of certain contagious diseases to other children attending the school; these requirements vary from one state to another.

    In the United States, certain vaccines are recommended for children between birth and 6 years (figure 1). Using combination vaccines can help to reduce the number of shots needed at each visit. (See “Patient information: Vaccines for infants and children age 0 to 6 years”.)

    The timing of vaccines is important; some vaccines are most effective when given to children at a particular age or in combination with other vaccines. A personal, customized vaccine schedule can be created at the CDC’s web site ( The schedule may be helpful in reminding parents when their child is due for vaccines.

    The CDC has also developed an online tool for parents of children younger than six years to help determine which vaccines have been missed and when the vaccines should be scheduled (

    WHERE TO GET MORE INFORMATION — Your child’s healthcare provider is the best source of information for questions and concerns related to your child’s medical problem.

    This article will be updated as needed every four months on our Web site (

    Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

    Patient level information

    Patient information: Vaccines for infants and children age 0 to 6 years
    Patient information: Vaccines for children age 7 to 18 years
    Patient information: Adult vaccines

    Professional level information

    Allergic reactions to vaccines
    Clinical trials of human papillomavirus vaccines
    Epidemiology, clinical manifestations, diagnosis and management of mumps
    Hepatitis A virus vaccination and postexposure prophylaxis
    Hepatitis B virus vaccination
    Meningococcal vaccines
    Pneumococcal (Streptococcus pneumoniae) conjugate vaccines in children
    Poliovirus vaccination
    Prevention of varicella-zoster virus infection: Chickenpox
    Recommendations for the use of human papillomavirus vaccines
    Seasonal influenza vaccination in children
    Standard childhood immunizations
    Treatment of varicella-zoster virus infection: Chickenpox
    Vaccinia virus as the smallpox vaccine

    The following organizations also provide reliable health information.

  • National Library of Medicine


  • National Institute of Allergy and Infectious Diseases


  • Centers for Disease Control and Prevention (CDC) National Immunization Program

          Toll-free: (800) 311-3435 begin_of_the_skype_highlighting              (800) 311-3435      end_of_the_skype_highlighting


  • National Foundation for Infectious Diseases

          Tel: (301) 656-0003 begin_of_the_skype_highlighting              (301) 656-0003      end_of_the_skype_highlighting

  • The Children’s Hospital of Philadelphia Vaccine Education Center



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