Your Children's Immune System: Kids’ Immunity Explained

Your Children's Immune System: Kids’ Immunity Explained

How can you strengthen your children’s immune systems?

As parents, caregivers, or educators, it’s essential that we understand how little ones' bodies fight off illness and build resilience against germs. 

Knowledge is power, and knowing truth from fiction when it comes to immunity will help you make it through the season of colds and flu with more confidence that you’re taking the right preventative steps.

In this post, we'll dive into the developing immune system of children: from its basic functions to the factors that influence its strength.

We'll explain what’s normal at each stage so you’re better equipped to handle the worries that come with caring for tiny, precious people.

Understanding children’s immune systems

Immunity is a hot topic, but most of us take its existence for granted. We rarely think about what makes up this system that protects us from countless invaders.

For a simple definition, we turned to a pediatric infectious disease specialist. Dr. Ashouri says:

“Our immune system is a series of cells, tissues and organs that, throughout our lifetime, protects us from different invading pathogens and keeps us healthy and able to resist many repeated infections.” (Kids and the Immune System)

Think of your child’s immune system as an intricate security system, constantly on the lookout to protect your child against invaders such as bacteria, viruses, fungi, and toxins. (Immune System — Overview, University of Rochester Medical Center)

Actually, your child has three types of immunity: innate, adaptive, and passive:

  • Innate immunity: All kids are born with a basic level of immune protection. That innate immunity includes skin (a protective barrier against germs), mucous, the coughing reflex, and stomach acid.
  • Adaptive immunity: This type of learned or active immunity develops when our bodies “adapt” a response to exposure to pathogens, like viruses and bacteria. We develop adaptive immunity throughout our lives through each accidental exposure and through vaccinations.
  • Passive immunity: This immunity is "borrowed,” and the protection is temporary. For example, antibodies from the placenta and breast milk pass on protection from the mother to the infant. 

Are children’s immune systems weaker?

In early childhood, we know that kids get sick a lot! But why is that? What’s going on with their immune systems during these early years?

Children's immune systems are still developing, which makes them more susceptible to infections. In the early years, their bodies encounter many germs for the first time, and their immune systems learn to recognize and respond to these invaders. 

The reality is that most kids get sick a lot, especially young children who are new to group care or school environments. It’s a normal part of childhood, and in fact, data shows that young kids are typically sick up to 50% of the time.

Some children may have a weakened immune system. This is called an immune system disorder or “immunodeficiency” and can be temporary (because of a recent illness) or long-term (because of a genetic disorder or disease). Extra precautions are often necessary to protect these children from infections. 

Most children, however, will pass through the round of childhood illnesses unscathed and stronger for the experiences. This learning process is crucial for building long-term immunity… But it also means they might get sick more often than adults!

So, let’s talk about those illnesses that challenge kids’ immunity.

Childhood challenges to the immune system

Challenges are learning opportunities for kids’ immunity.

Just as your kids are learning and practicing a wide range of cognitive and physical skills, their adaptive immune system is also learning how to recognize and defend against invaders. This is called immunological memory, and it’s key to developing a stronger immune system over time. 

The list of common childhood illnesses and infections is long. Among the most familiar are…

  • Viral infections: including the common cold, COVID, influenza, respiratory syncytial virus (RSV), chickenpox, measles, and mumps
  • Bacterial infections: including strep throat, ear infections, and meningitis 
  • Multi-cause illnesses: including tonsillitis and gastroenteritis (commonly known as the stomach flu), which can be caused by viruses or bacteria

Parents and caregivers can feel helpless and overwhelmed going through so many childhood illnesses. You can take some comfort from knowing that after most mild or moderate illnesses, kids bounce back with a stronger immune system. It’s practice!

Practice doesn’t make perfect with the common cold, however. Kids and adults simply don’t develop total immunity against rhinovirus, which causes the cold. That’s because there are hundreds of these viruses, and they’re all just a little different — enough to keep our immunity guessing!

If you want to prevent the common cold from keeping your kid home from school and sabotaging your family plans, your best strategies are to avoid exposure and keep their bodies strong and healthy to recover faster.

Stages of child immune development 

How long does the process of typical immune development take, and what can you expect? This is the question every new parent wants answered! The fact is, it’s a process that takes all of childhood, and the development of immunity is fascinating.

Your child’s immune system develops and adapts from in the womb to adolescence. Genetics, environment, nutrition, and overall health influence your child’s ability to fight off infections. 

Let’s find out how it works.

In utero immune development:

As mentioned, children develop some innate immunity early and borrow passive immunity from mom

In utero, fetuses are immunized through antibodies that are transferred from the placenta and amniotic fluid. The amount and type of protection depends on the mother’s exposure to viruses and bacteria.

This transfer of immunity from mother to fetus happens largely in the last few months, which means that babies born prematurely miss out on some of that passive immunity.

A mother’s health and nutrition also influence fetal immune development. Vitamins, minerals, and essential fatty acids are crucial for proper immune development from the earliest phases of development.

Immune development in newborns and infants:

When a baby is born, virtually every germ is completely new to their immune systems. That’s why infants are so vulnerable to infections and why so much care and protection is needed while they develop adaptive immunity.

In the first few weeks or months, passive immunity still provides protection, but it starts to decline.

Just as passive immunity declines, adaptive immunity ramps up! Over the first months of infancy, children start producing more of their own antibodies, especially when exposed to various germs.

This exposure helps their immune system mature, though it often leads to frequent minor illnesses like colds. (Which can be scary when you’re caring for a tiny human!)

During this time, breastmilk is naturally protective because it contains antibodies and immune factors. However, if breastfeeding wasn’t an option for you or your child, know that your infant has plenty of opportunities to build immunity through other means.

Infant vaccines also protect children against some of the most dangerous infections, including certain bacterial infections.

Developing immunity in toddlers and preschoolers

By ages three to four, children are able to produce their own antibodies to fight off infections fully. Toddlers and preschool children have a more developed immune system compared to infants. 

These kids are also busy swapping toys and often swapping drool with other kids! All of this exposure helps in building immunity.

Elementary school kids’ immunity:

By ages seven to eight, most children’s immune systems are fully developed.

They’ve spent quite a few years developing adaptive immunity through exposure to various pathogens.

While they still get sick, at this age, you might notice that your kids don’t seem to get  as sick as before. So, you can relax a bit each time they get the sniffles!

You’ll also notice you go for longer stretches without taking a sick day because they’ll get sick less often.

Teenage immunity (the final stretch!):

Ever wondered, “At what age is your immune system the strongest?” For many people, immunity in the teen years is as strong as it will ever get.

Children's immune systems peaks at around puberty. By this point, they’re relying on their immune memory of the dangers they’ve encountered throughout childhood. 

However, this stage can also be affected by hormonal changes, stress, sleep patterns, and lifestyle choices (like diet and exercise), which can influence immune function. 

How to help kids develop healthy immunity 

Many factors influence the healthy development of a child’s immunity. These include nutrition, sleep, hygiene, genetics, exposure, and more.

We can’t change our genetics, and we can’t control every factor of immunity (like exposure to germs!) However, we can help them build a robust immune system that’s ready to battle the big baddies that come their way. 

Specifically, we can help kids build immunity through:

  • Nutrition and diet
  • Limiting sugar intake
  • Establishing healthy sleep routines
  • Practicing good (but not excessive) hygiene
  • Working with your healthcare provider to use antibiotics sensibly
  • Supporting mental health

There's a lot you can do to help your kids develop their immune systems! It is never too early or too late to start.

Learn more about how to strengthen immunity in kids here.

Nurturing resilient immunity in children

Now you know! Each sniffle and cough is part of a crucial developmental process for your child.

Children's immune systems evolve from the womb to the teenage years, encountering and overcoming numerous challenges. Of course, we worry at every step of this journey, but take a moment to recognize these challenges as steps toward long-term immunity. 

As you guide and care for your child through the tough times and in between, remember that you're not just managing the occasional illness; you're helping build the foundation of your child's health for years to come.

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