Who Is at Risk From Unvaccinated Kids?

Vincent Iannelli, MD
·5 min read

Immunization not only protects you and your child from vaccine-preventable diseases but everyone around you as well. This is because herd immunity dictates that if most people are immune to a disease, then the risk of community transmission is diminished, as well as the incidence of disease and illness.

Even people who refuse vaccination or don't believe in herd immunity are still part of the process. As the risk of infection decreases within their communities, they are recipients of the benefits of community-wide vaccination whether they realize it or not.

Even so, if a large sector of the population does not get the recommended vaccines, diseases once thought eliminated can begin to return. Such has been the case with diseases like measles, which was declared eliminated in the United States in 2000 but is now being seen in pockets throughout the country.

Jiaqi Zhou / Verywell
Jiaqi Zhou / Verywell

Myths and Misconceptions

One of the classic myths among anti-vaccine proponents is that unvaccinated children pose no risk to the public because most people are vaccinated. The underlying conceit is that if harm is done, only the unvaccinated individual will be affected.

As the recent measles outbreak has shown, this is not the case. In fact, as the spread of measles continues in the United States, others who might otherwise be safe are beginning to get affected.

Among them:

  • Infants who are too young to be vaccinated are often exposed at hospitals or healthcare provider's offices where someone with measles is seeking care.

  • People with weak immune systems are vulnerable to infection, as happened in Pittsburgh in 2018 when a college student was believed to have exposed around 100 people with cancer to measles.

  • Healthcare workers are often placed at needless risks, such as occurred in 2013 when a healthcare provider developed measles encephalitis during the large outbreak in Fort Worth.

Outbreaks like these affect everyone in a community, even those who do not get sick.

In 2011, there were 107 confirmed measles infections in the United States. To contain the outbreaks, local and state health departments had to spend between $2.7 and $5.3 million, according to a 2014 study published in the journal Vaccine.

Related:Top 20 Vaccines You Should Know About

Children at Risk

Among the groups who are most at risk of the anti-vaccine movement are infants and children who are too young to be vaccinated. These are often children of parents who fully intend to get them vaccinated but simply can't because of their age.

This is an especially big problem with pertussis (whooping cough) as infants don't begin to achieve full protection from the DTaP vaccine until their third shot at 6 months of age. In the California pertussis outbreak of 2010, 10 infants died, nine of whom were less than two months old.

Among some of the other vaccine-preventable diseases that younger children may get during gaps in their vaccination schedules:

  • Influenza: Children don't get their first dose of the influenza vaccine until 6 months, with a second dose delivered a month later.

  • Measles: Children don't get their first dose of the MMR vaccine until they are 12 months old and aren't fully protected until they get their second dose at 4 to 6 years of age.

  • Chickenpox: Chickenpox, like measles, is scheduled so that children get their first dose of the varicella vaccine at 12 months and the second dose at 4 to 6 years of age.

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

The Centers for Disease Control and Prevention (CDC) recommends the following vaccinations before the age of 2:

Related:Mandatory vs. Recommended Vaccines

Immune Deficiency Risks

Children and adults with weak immune systems may be at risk of vaccine-preventable diseases for different reasons. Some are immunocompromised and cannot receive certain vaccines (particularly live vaccines) because the vaccines can end up causing illness. Others are unable to achieve the same immune protection following vaccination due to an underlying immune deficiency.

In either instance, the lack of an intact immune system places these individuals at greater risk of infection and illness than those with a robust immune response.

There are at least 180 different primary immune deficiency disorders (rare, genetic disorders that impair the immune response) and many secondary ones (like HIV, organ transplants, and cancers like lymphoma and leukemia) that can place a child at an increased risk of infection.

One example involved a toddler with acute lymphoblastic leukemia (ALL). According to the CDC report, a 4-year-old with ALL developed complications from a chickenpox infection 22 days after exposure despite being vaccinated against the disease. She died several days later due to multi-organ failure.

According to CDC officials, the rate of unvaccinated children in the United States is rising. Today, around 1.3% of children remain unvaccinated by 24 months, up from 0.3% in 2001.

Allergy Risks

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

Although uncommon, a life-threatening allergic reaction may preclude some children from getting a vaccine or completing a vaccine course. For example, if a child has had a life-threatening reaction to the antibiotic neomycin, they would likely be allergic to the polio vaccine, chickenpox vaccine, and MMR vaccine too.

Unlike children whose parents refuse them vaccines, these kids have true medical exemptions to getting vaccinated.

Related:The Safety and Science of Vaccine Ingredients

A Word From Verywell

Vaccines are effective. Even so, an aversion to vaccines places the wider community at risk of diseases that should be fully under control.

Today, there are around 24,000,000 children under the age of 5 in the United States. While the majority of these kids are vaccinated, data from the CDC suggests that nearly three in seven do not complete the 7-vaccine series recommended by age 3. That leaves a lot of kids under-protected against diseases they might otherwise avoid.

If you are unsure whether you need vaccinations or vaccination boosters, speak with your healthcare provider. Even if you've not been to a healthcare provider in a long time, they can help you catch up whatever your age.

Related:Vaccination and Autism Myth