Is the COVID Vaccine Safe for Children? A Pediatrician and Immunologist Weigh in

How traditional vaccines work, and how the COVID-19 vaccine is different

Vaccines work by training the immune system to recognize foreign pathogens that invade the body, such as viruses and bacteria. Like distributing a mug shot, vaccines give the immune system an advance notice to find and fight a foreign invader. Without vaccination, the first time the immune system sees a particular pathogen, it can take up to two weeks to develop a highly trained, specific immune response. Thus, vaccination gives the immune system a head start and limits the damage caused by the intruder.

Traditional vaccines generally consist of dead pathogens or small parts of them. The pediatric COVID-19 vaccine produced by Pfizer / BioNTech uses a newer, mRNA vaccine technology. COVID-19 mRNA vaccines work by telling cells in the body to produce pieces of the SARS-CoV-2 virus, specifically the spike protein. The spike protein is what SARS-CoV-2 uses to enter and infect cells. When trained to identify and block the spike protein, the immune system can prevent the virus from getting into our cells and help remove the virus from our bodies.

Traditional vaccines consist of manufactured and purified virus parts. In contrast, mRNA vaccines use the pathway described above to direct cells in the body to make a component of the virus, like the spike protein for the COVID-19 vaccine. The mRNA from the vaccine mainly enters muscle cells at the injection site, and some travels to the lymph nodes. Display of vaccine components within lymph nodes is an important feature of vaccines, allowing the immune system to mount the most effective response. Importantly, the mRNA does not permanently alter cells in your body and cannot change your DNA. The spike proteins are displayed by a few cells for a short period of time (days to weeks), before being degraded themselves. In our cooking analogy, an mRNA vaccine would be like receiving a recipe from your neighbor and discarding it after you finished cooking your meal. The mRNA vaccine recipe cannot become part of the published master cookbook. Having seen the “mug shot” of the virus (via exposure to only the spike protein), the immune system develops a “memory” of it, so will be more prepared to rapidly respond to an actual SARS-CoV-2 virus infection.

The technology required to generate mRNA vaccines has been in development for decades. This mRNA technology opened up a fast path to new vaccine generation for novel infectious agents. Traditional vaccine development requires overcoming multiple challenges, including growing the virus in the lab, purifying virus parts, and formulating them into an optimal delivery vehicle. These are all complicated, time-consuming steps that are not required for mRNA vaccine development.

Decades of research into related viruses, such as SARS and MERS, also allowed effective COVID-19 vaccine design. Immediately after sequencing of the spike protein, mRNA was quickly tested for efficacy: first in animals, then in clinical trials. No short-cuts were taken in the clinical trials. Vaccine approval followed all standard safety protocols and the trials were full size. To speed vaccine distribution, the government paid in advance to scale up manufacturing before knowing if the clinical trials would actually be successful. Trial results also came in quickly, because the virus exposure in the community was so high.

Like distributing a mug shot, vaccines give the immune system an advance notice to find and fight a foreign invader…(they work by giving) the immune system a head start (which) limits the damage caused by the intruder.

Common Questions about COVID-19 Vaccination

COVID-19 vaccines are currently approved for children as young as five years old. Parents now have questions about the best decision to keep their children safe during this pandemic. Here, we address some of the most common questions. For a very brief primer on immunology and a discussion of other concerns about general pediatric vaccines, please view our previous article.

Since kids are less susceptible to severe effects of SARS-CoV-2 infection than adults, why should children receive the COVID-19 vaccine?

While most children recover from infection without major issues, COVID-19 can be a serious illness even for children. Many parents regularly get their kids flu shots to keep them healthy and in school. Flu shots are highly recommended, because children are at risk of serious effects from flu infection. There are about 30-200 pediatric deaths due to the flu per year. The risks from COVID-19 infection in children are actually greater than that for the flu. In the past two years, thousands of children in the United States have been hospitalized with COVID-19, and over 700 children between the ages of 5-18 have died, including during the most recent wave of the omicron variant.

Typical COVID-19 symptoms are fever, cough, nausea, and diarrhea. In children, COVID-19 infection can also cause cardiovascular and neurological symptoms. As discussed further below, COVID-19 infection is associated with heart inflammation (myocarditis). Children can suffer from long COVID: many months of fatigue and neurologic symptoms such as brain fog. And COVID-19 infection has been associated with about a two-fold increased risk of developing childhood diabetes.

Another serious complication of COVID-19 infection is Multisystem Inflammatory Syndrome in Children (MIS-C). MIS-C is an exaggerated immune response triggered by viruses, such as SARS-CoV-2. This inflammation can occur in multiple organs, including the heart, lungs, brain, kidney, skin, eyes, and gastrointestinal tract. MIS-C can present 2-6 weeks after infection with SARS-CoV-2 and can even affect children who had few symptoms from the virus. It has been reported that about one in three to four thousand children who have been infected with SARS-CoV-2 develop MIS-C.

People at an elevated risk of disease include grandparents, adults and children with asthma, obesity, diabetes, heart or lung disease, and sickle cell anemia. Pregnancy also increases the risk of severe outcomes from SARS-CoV-2 infection. Some diseases and medications reduce the strength of the immune system, increasing the risk of infection. Unfortunately, vaccines are less effective for people under such conditions, including cancer patients, transplant recipients, and people with autoimmunity. Ultimately, vaccines protect both our kids and our community.

How concerning is the risk of myocarditis?

There are some indications that COVID-19 vaccines could increase the rate of myocarditis, particularly for adolescents and young men. However, these events are rare, making the cases difficult to study. To put this risk in perspective, let’s look at some of the numbers. The overall incidence of myocarditis in the general population is about 10-20 per 100,000. That amounts to about a 0.01% risk of myocarditis without COVID-19 infection or vaccination. The cases of myocarditis after COVID-19 vaccination appear to be highest in young males (16-30 years old). Two studies found rates of myocarditis after COVID-19 vaccination to be elevated, but similarly rare as the estimated incidence in the general population.

However, COVID-19 infection is also associated with myocarditis. One study found COVID-19 infection to increase the risk of myocarditis by about 16-fold. An analysis in the United States found that vaccination reduced the incidence of myocarditis following COVID-19 infection in the highest-risk group (12-17 year old males) by 6-fold. The bottom line is that the incidence of myocarditis after vaccination is very rare, and vaccination could reduce the rate of myocarditis caused by COVID-19 infection itself.

How do we weigh the benefits against the risks?

To assess our vaccine decisions, we should weigh the benefits against the risks. While there is a very rare risk of adverse effects from vaccination, there are more chances of negative outcomes from COVID-19 infection than from vaccination. During the last two years of the pandemic, over 700 children between the ages of 5-18 have died from COVID-19, including during this recent wave driven by the omicron variant. To help think about that level of risk, let’s consider how we reduce risks in other areas of our children’s lives. Very few children drown, but parents take action to teach their kids to swim to reduce the risk of drowning. (An average of 357 children aged 5-17 drowned per year from 2010-2019.) Swimming with lessons has reduced risk compared to swimming without lessons. Likewise, exposure to SARS-CoV-2 after vaccination has reduced risk compared to COVID-19 infection without vaccination.

From the numbers discussed above, we can conclude that our kids are more likely to suffer harm from COVID-19 infection than vaccination. Although not entirely without risk, the chance of vaccine injury is very rare, while providing multiple great benefits. We should not only consider the risk of death from COVID-19 infection, which is fortunately very low, but also other negative outcomes.

As discussed in the previous sections, COVID-19 infection can cause multiple health challenges such as MIS-C, neurological events, myocarditis, diabetes and long-COVID. Vaccination can reduce the rate of such outcomes. And for the fortunate majority of children who will only have mild disease, vaccination reduces the duration of infection, keeping children in school and engaged in their normal daily activities. Vaccination can also help protect vulnerable people in our community, especially the immunocompromised.

…Vaccination reduces the duration of infection, keeping children in school and engaged in their normal daily activities. Vaccination can also help protect vulnerable people in our community, especially the immunocompromised.

Were the trials large and long enough to assess safety in children?

The trials were able to be conducted quickly, in part because infection rates within the community have remained so high. Such high chances of virus exposure for study participants increased the ability to do robust statistical analysis of the study results. The vaccines ran through full clinical trials and completed normal protocols to prove safety and efficacy. The trials for children were also delayed to start after the adult studies provided initial safety and efficacy data.

How is vaccine dosage determined?

Pediatric vaccine doses are determined based on what is not just a safe and effective dose but what is going to be a safe, effective, and “friendly” dose. Unlike medications, vaccine doses are not based on weight, but are instead based on the age of the child. This is due to the immune responses in different age groups. In general, children have higher immune responses than adults. It is believed that children’s immune systems are generally the best around age 15. This is thought to be the reason that 12-15 year olds had the highest level of antibodies after receiving the adult dose. In the initial pediatric trials, Pfizer tested 4 different vaccine doses, including the adult dose. The pediatric trial monitored children in all four groups for side effects and antibody levels. Subsequently, the two lower doses were chosen for the full clinical trial. In the end, the 10-microgram dose was chosen as it had comparable levels of antibodies as young adults and had a good side effect profile.

In the trial for children under 5, the first low dose selected by Pfizer did not give as good of an immune response as expected after 2 doses, so a third dose is being studied. More information and data on this vaccine should be available soon.

Could vaccines cause long term side effects?

Some people wonder if vaccines could cause unknown side effects in the distant future. Unfortunately, this idea is promoted by groups who spread mis-information about vaccines. Examples of long-term future side effects of vaccines are virtually unheard of. Because vaccine side effects result from the activity of the immune system, they mostly occur within about a month of vaccination.

We should be reassured that potential side effects of vaccination are not hidden, but are closely evaluated. All vaccine side effects occur more often and are more severe during infection than after vaccination. For example, while very rare, Guillain-Barre syndrome occurs about 17 times more often after flu infection than flu vaccination. If the benefits of vaccination do not exceed the risks, then the vaccines are not approved. Regulators also pull vaccines from the market if they find rare events after approval. For example, use of a Dengue virus vaccine was limited in 2017 (for reasons that are particular to Dengue infection, unlike COVID-19 or other infectious diseases).

Is natural immunity better than vaccination?

The immune system is an incredible part of God’s creation. Our immune system fights off infections all the time, and our lives depend on this protection. Fortunately, vaccinations can also help to teach our immune system what is coming. This is like the difference between going into battle with or without intelligence. The body’s immune response to an actual infection is less predictable than the immune response to vaccination. Infection can result in severe illness, which can be avoided by vaccination. While natural immunity can at times provide a broad immunological memory against a wide range of pathogens, it comes at the cost of increased illness and risk.

Will children need booster shots?

Boosters are currently only recommended for children ages 5-11 with compromised immune systems. The pediatric initial trials are just now passing the 6 month point, so data on boosters for the general pediatric population should be coming soon. For children over 12, boosters are currently recommended at least 5 months after the second shot. In adults, the booster shots increase antibody levels to block viral infection. There is also some evidence that the booster shots increase the diversity of the immune response. Such increased diversity can create immunity to different variants of the virus, as well as to other SARS family member viruses.

Why do I need to be vaccinated if God is in control and I trust Him with the health of my family?

God is sovereign over all creation, including over science and technology. All truth is God’s truth: including the truth revealed by God’s word in the scriptures and the truth we find as scientists studying God’s creation. God made people with incredible minds, with the ability to learn complicated concepts in science so that we could understand how the world works and worship him for his wonderful creation. God’s creation mandate to subdue the earth in Genesis 1 includes technology. From Colossians 4:14 we learn that the apostle Luke was a physician. Clearly, God gave humanity the ability to create new technologies to improve our world, enhance human life, and improve human health.

As Christians we need to be discerning about which new technologies to use and their ethical implications, but we do not need to fear them…Based on the growing evidence of their safety and effectiveness, we can be grateful to the Lord for his provision of COVID-19 vaccines to help reduce suffering during this pandemic.