From disease to vaccines: all you need to know about COVID-19 in children

After 20 months from the declaration of the pandemic in March 2020, science advanced at a faster pace than ever to keep up with the ever-changing demands of the COVID-19 emergency. In December 2020, the Food and Drug Administration (FDA) for the United States authorized the first two COVID-19 vaccines for adults after several rounds of clinical studies. Shortly after FDA’s approval, many countries around the world started benefitting from the effects of vaccination, and the number of severe cases of COVID began to decline. Although vaccines have proven to be excellent tools to prevent severe illness and death in adults, the debate today revolves around children and if they should be vaccinated as well. This is especially important to discuss since schools and public places have reopened worldwide, and children are becoming more exposed to the virus than ever before. To analyze the situation, let’s review some of the main differences of COVID-19 infection in children and adults and how vaccines are engineered to be used in different age groups.

How does COVID manifest differently in children and adults?

Although SARS-CoV-2 can infect anyone regardless of age, the manifestations of the disease can vary in each individual. It is true that children generally seem to have a milder disease presentation when compared to adults, but this does not mean that the disease cannot cause any complications and long-term consequences for kids. Scientists think children have milder manifestations of COVID-19 because they have fewer angiotensin-converting enzyme 2 (ACE2) receptors in their nose and lung cells. ACE2 is a cell protein that, in addition to its normal physiological functions in our body, happens to be key for viral entry and the development of infection by SARS-CoV-2. Another theory is that because children have less experienced immune systems than adults, they do not produce exaggerated immune responses, which are often the reason why adults end up in the hospital with severe disease. COVID-19 in terms of severity seems to be different from most respiratory viruses, including influenza (the flu), where younger children and older adults usually present more severe symptoms than the rest of the population.

Children have milder COVID-19 manifestations, which does not mean they cannot be infected. Only in the United States, over 6.6 million children have tested positive for SARS-CoV2 since the declaration of the pandemic. Although the mortality rate in children is low, many medical sequels of COVID have been reported in children and teenagers following asymptomatic or mild disease. These include dehydration, chronic cough, persistent fatigue, inflammatory conditions, headaches, insomnia, difficulty concentrating, and many others that can last anywhere from a few days to months depending on the case. Some parents have observed that some of these (like insomnia, headaches, and difficulty concentrating) persist for more than 6 months after their kids got sick.

How are the vaccines different?

The FDA has provided emergency use authorization for the Pfizer-BioNTech COVID-19 vaccine in children aged 5 and older, while the clinical trials for vaccines for younger children are still ongoing. This vaccine was tested in more than 4,600 kids aged 5-11 and the results showed that it is 91% effective in preventing serious illness, while in the 12-15 age group the effectiveness was 100%. This means that all children who participated in the trial developed an appropriate level of antibodies after receiving the vaccine. Also, children 12-15 have reported the highest antibody buildup of all groups.

The clinical trial also included a 2-month follow-up for adverse effects with no safety concerns. This means that the safety of this vaccine has been validated during a reasonable period of time as it is important to consider that for vaccines serious adverse events would present themselves immediately or in hours after their administration. While the mechanism of action and ingredients of the vaccines are equal for children and adults, there are some key differences between the vaccination scheme for these two age groups. First, people over 12 years old receive 30 micrograms of the vaccine, while children under 12 only receive 10 micrograms of each dose separated by a period of approximately six weeks. This is because children’s immune systems are better than adults’ at creating immune responses; therefore, they achieve sufficient antibody concentrations to fight the infection with a smaller dose. This is also beneficial because a lower dose can also further reduce the risk of rare complications, making the vaccine safer.

Another difference between a child’s and an adult’s vaccine is the liquid used to keep the vaccine stable in a fridge after being prepared for injection. This liquid allows keeping the vaccines stable in refrigerators for up to 10 weeks. Lastly, the vaccines for kids have fewer salts, which are also used to stabilize the vaccine.

The most frequently reported mild adverse effects in children include fever, pain at the injection site, headaches, and fatigue that can last 1 to 3 days after vaccination. Given the positive results for safety and efficacy, the vaccine manufactured by Pfizer has been authorized in the United States, the European Union, and Canada. Moderna has also submitted its results for authorization of its use in children and will also have a smaller dose compared to the adult vaccine.

How will vaccinating children impact us all?

Vaccines not only protect children from serious complications, but vaccinated children protect the adults around them who may be at high risk of developing the severe presentation of COVID-19. Vaccinated children contribute less to the spread of the virus, especially among the family members who live with them. This ultimately helps to reduce the burden on families and healthcare services caused by COVID-19. One of the biggest problems for children has been the death of their (grand)parents or caregivers due to COVID-19. Given that children are going back to school and participating in more activities, the risk of them bringing the infection home is higher. Thus, the chance of their family members becoming infected is higher too.

Furthermore, children have been overlooked during the pandemic because there is a false belief that given that they show milder or no symptoms, they do not contribute to the spread of the disease in general. Every person who gets infected can transmit the virus to others, and the more transmission, the more virus variants are likely to appear. Regardless of the person's age, each infection gives the virus a chance to mutate, producing new variants that could spread more easily or cause more dangerous symptoms. Vaccinating everyone, regardless of their age, is important to prevent this.

Vaccines for children: Yay or nay?

The only reason a child should not receive a COVID-19 vaccine is if they have a history of anaphylaxis or non-severe immediate allergic reactions to any of its ingredients, an allergy to polyethylene glycol, or if they had an allergic reaction to the first dose (which is very rare). Vaccines are excellent tools to prevent serious illness and complications from COVID-19 in both children and adults. They are also less likely to develop long-term symptoms of the disease, like chronic cough and fatigue and trouble concentrating and sleeping. Vaccinating children makes it safer for them to go back to school, participate in group activities, sports, and other related gatherings. Moreover, it reduces the burden on the health system by preventing the generation of new variants of the virus and reducing the rate of transmission among the general population.

Although vaccines can reduce the risk of infection with the virus to a certain degree, we still need to continue ventilating spaces, wearing a facemask, and practicing social distancing as much as possible since these measures reduce our risk of infection even further. Vaccines give our immune system a heads up before having to fight the real deal. They are safe and useful and will reduce our chances of getting severely ill no matter our age group. It's your turn to make our world a safer place, one vaccine at a time.

Contributed by: Text: Claudia Minutti


COVID-19 in children

COVID-19 vaccines for children

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