Who is at Risk from Unvaccinated Kids

Are your kids at risk during an outbreak

Person's hand examining fever of a child
Could your sick child have measles and be putting others at risk?. Eric Audras / Getty Images

Why Immunize?

Most people understand that we get our immunizations to protect our children and ourselves from vaccine-preventable diseases, which often cause life-threatening infections.

The vaccines we get also protect everyone around us. Herd immunity dictates that if most people are immune to a disease, then it will be unlikely that anyone will get sick and infect anyone in the herd, including those who are unprotected.

Although many who purposely don't vaccinate their children or themselves claim they aren't part of the herd or don't believe in herd immunity, they still are. They are simply an unprotected member of the herd who relies on the rest of us for protection.

Anti-Vax Myths and Misconceptions

One of the classic myths or misconceptions that anti-vax folks use to justify starting outbreaks of vaccine-preventable diseases is saying that their intentionally unvaccinated kids pose no risk to the rest of us, because we have all had our vaccines.

They typically think that it is only their own unvaccinated children and themselves who will be at risk for vaccine-preventable diseases, which they often think are not dangerous, another classic anti-vax myth.

Unfortunately, as the increasing number of outbreaks of measles in the United States are showing, neither anti-vax myth is true.

In fact, as we continue to hit new records, we are seeing:

  • infants who are too young to be vaccinated get caught up in the outbreaks as they are exposed at a doctor's office or hospital, where the person with measles is seeking care
  • people with immune system problems getting needlessly exposed to measles, as happened in Pittsburgh recently, when a college student with measles possibly exposed about 100 cancer patients
  • people develop severe complications of measles, such as the health care provider who reportedly developed measles encephalitis during the large measles outbreak in Fort Worth

We are also learning how much it costs to contain a measles outbreak.

There were 220 cases of measles in the United States in 2011. To contain just 107 of those cases in 16 outbreaks, "the corresponding total estimated costs for the public response accrued to local and state public health departments ranged from $2.7 million to $5.3 million US dollars."

So who is put at risk when someone chooses to not get vaccinated?

High Risk - Too Young to be Vaccinated

Among the groups of people who are most at risk from those who are unvaccinated are infants and children who are simply too young to be vaccinated.

These are often the children of parents who plan on getting them fully vaccinated, following the latest immunization schedule of the American Academy of Pediatrics, but they just aren't old enough yet to be protected.

This is an especially big problem with pertussis (whooping cough), when infants don't begin to have any protection until they get their third dose of the DTaP vaccine when they are six months old.

In the big pertussis outbreak in California in 2010, of the ten infants who died, nine were less than two months old.

And we see this with measles too, since children don't get their first dose of the MMR vaccine until they are twelve months old and aren't fully protected until they get the second dose, at age four years. Keep in mind that young children should get their MMR doses earlier if they will be traveling out of the United States.

Vaccine-preventable diseases that younger children can be at risk for until they are old enough to get their vaccines can also include:

  • influenza - first dose of the flu vaccine at age six months, with a second dose a month later.
  • chicken pox - like measles, children get their first dose at age twelve months and a second dose at age four years. The second dose can be given as early as three months after the first dose though, especially if your child was recently exposed to chicken pox.

Younger children are also at risk for polio, rubella, and mumps until they are old enough to be vaccinated.

Considering that there are about 4,000,000 births a year in the United States, that puts a lot of infants at risk for measles, pertussis, and other vaccine-preventable diseases.

For measles, as kids aren't fully protected until they get their second dose of the MMR vaccine when they are about 4-years-old, that means an additional 12,000,000 toddlers and preschoolers are potentially at risk.

High Risk - Weak Immune System

Children and adults with weak immune systems can fall into several broad categories, including those who can't receive some vaccines because they have a weak immune system and those who may be fully vaccinated, but no longer have any immune protection because they developed an immune system problem.

And if they were to be vaccinated, depending on their degree on immune suppression, the vaccine likely would not work well.

There are at least 180 different types of primary immune deficiency disorders and many secondary ones. Among these immune system disorders that might put children at risk for some vaccine-preventable diseases include:

  • Antibody deficiencies - X-linked agammaglobulinemia, common variable immunodeficiency, selective IgA deficiency, IgG subclass deficiency
  • Partial and complete T-lymphocyte defects - severe combined immunodeficiency (SCID) disease, DiGeorge syndrome, Wiskott-Aldrich syndrome, ataxia-telangiectasia
  • Defects in phagocyte function - Chronic granulomatous disease, leukocyte adhesion defect, and myeloperoxidase deficiency
  • HIV/AIDS
  • Many kinds of cancer
  • Transplants receiving immunosuppressive therapy
  • A disorder requiring treatment with immunosuppressive doses of steroids

According to the Immune Deficiency Foundation, "We want to create a 'protective cocoon' of immunized persons surrounding patients with primary immunodeficiency diseases so that they have less chance of being exposed to a potentially serious infection like influenza."

It shouldn't be hard to see that if some children are intentionally not getting vaccinated, then they certainly do pose a risk for these children with immune system problems.

A CDC report of the death of a vaccinated child with leukemia is a heart breaking illustration of how kids with immune system problems can be at high risk from vaccine-preventable diseases. The four year old with acute lymphoblastic leukemia (ALL) developed a fever 22 days after being exposed to chicken pox and just after starting another round of chemotherapy, which causes profound immunosuppression. She was hospitalized and died of multi-organ failure a few days later.

The Medical Advisory Committee of the Immune Deficiency Foundation also warns that "the increased risk of disease in the pediatric population, in part because of increasing rates of vaccine refusal and in some circumstances more rapid loss of immunity, increases potential exposure of immunodeficient children."

High Risk - Can't Be Vaccinated

There are also situations where a child might be old enough to be vaccinated and have a strong immune system, but still can't get some or all of his vaccines.

Although not common, the most well known would be a child who had a life-threatening allergic reaction to a previous dose of the vaccine or a component of the vaccine. For example, if you have had a life-threatening reaction to the antibiotic neomycin, then you shouldn't be vaccinated with the chicken pox, polio, or MMR vaccines.

These are the children who have true medical exemptions to getting vaccinated.

High Risk - Vaccinated and Unprotected

Vaccines are effective.

By the time most children are two years old, they are protected against fourteen vaccine-preventable diseases, including diphtheria, Haemophilus influenzae type b, measles, mumps, pertussis, and polio, etc.

Some vaccines are more effective than others though. The measles vaccine, for example, is over 99% effective at preventing measles after two doses. On the other hand, the acellular pertussis vaccine is only about 80 to 85% effective.

Even if the measles vaccine is over 99% effective though, if there are almost 74,000,000 children and teens under age 18 years in the United States, that would still put a lot of kids at risk from people who are intentionally not vaccinated.

Whether it is a 6-month-old going to the pediatrician for a well child check up, a 6-year-old with leukemia going to the hospital for chemotherapy, or a 16-year-old with chronic granulomatous disease, it should be clear that a lot of people are unnecessarily put at risk when someone makes a decision to not vaccinate their kids or to use an alternative immunization schedule.

 

Sources:

CDC. Notes from the Field: Varicella-Associated Death of a Vaccinated Child with Leukemia — California, 2012. MMWR. February 21, 2014 / 63(07);161-161.

General Recommendations on Immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR. January 28, 2011 / 60(RR02);1-60.

Epidemiology and Prevention of Vaccine-Preventable Diseases. The Pink Book. 12th Edition Second Printing

Immune Deficiency Foundation, USA. IDF Patient & Family Handbook for Primary Immunodeficiency Diseases FIFTH EDITION

Medical Advisory Committee of the Immune Deficiency Foundation. Recommendations for live viral and bacterial vaccines in immunodeficient patients and their close contacts. Journal of Allergy and Clinical Immunology. Available online 28 February 2014.

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