The ability to get a child vaccinated has created a rush by some parents to secure an appointment for their child but for other parents, questions remain. This caution is understandable, says Kelly Moore, MD, MPH, president and CEO of the nonprofit Immunization Action Coalition. “Even when parents had the vaccine themselves, they still want to know how it will benefit their child before they have them get it,” she says. In a poll of parents taken in late October by the Kaiser Family Foundation (KFF), just before shots were authorized for 5-  to 11-year-olds, 27 percent said they will immunize their child as soon as possible, while a third planned to wait and see how other kids fare. Thirty percent said they would not have their child vaccinated, similar to the percentage who said they wouldn’t immunize their 12- to 17-year-olds either. We asked experts to explain the science behind the authorized Pfizer vaccine and to provide insights into what parents need to know. RELATED: Coronavirus Alert: The Latest News, Data, and Expert Insight on the COVID-19 Pandemic This means that by the time clinical trials began for children under age 16, hundreds of millions of the shots had already been administered to American adults and older teens and were proved to be safe and effective. Clinical trials subsequently conducted on several thousand younger kids aimed to discover the right dose, to confirm a child’s immune system would react in the desired way to the vaccine, and to ensure vaccine safety in children of various ages. All data from these trials was reviewed by the FDA and CDC before the agencies authorized and recommended the vaccine for this age group. “We don’t just make assumptions that what worked for adults or even a 12-year-old will work in a 5-year-old. We demand extensive trials from the manufacturer, and they have done that,” says Robert M. Jacobson, MD, medical director of the primary care immunization program at the Mayo Clinic in Rochester, Minnesota. Millions of children ages 12 to 15 have already received doses of the Pfizer vaccine. And they are working: The CDC announced in September that the shots have been 93 percent effective in keeping kids this age from being hospitalized. RELATED: What You Need to Know About COVID-19 Vaccines

2. Common side effects are similar for kids and adults.

Side effects in children found during the clinical trials primarily include pain at the injection site and tiredness, headaches, and, occasionally, fever, similar to the impact on many adults. The clinical trials conducted in children found no serious adverse effects linked to the shots. Scientists are keeping the closest eye out for an extremely rare side effect called myocarditis, inflammation of the heart muscle. According to the CDC, young men and adolescent males have been the most affected by this complication. A recent Israeli study published in October in the New England Journal of Medicine looked at the incidence of myocarditis following mRNA vaccination and estimated that it occurs in roughly 1 in 26,000 males. Fortunately, with treatment, most returned to normal cardiac function before leaving the hospital. Long-term studies are underway, according to the CDC. It is unknown at this time whether children in the newest authorized group of 5 to 11 are at increased risk for myocarditis. Because the condition is so rare, doctors will know if it affects kids this young only after many thousands are vaccinated. Authorized vaccines for kids in this age group are one-third of the adult dose, 10 micrograms (mcg) instead of 30. The shots are packaged in different, smaller vials, and smaller needles are used. The schedule for shots for children 5 to 11, as well as for kids 12 and over, is two doses given three weeks apart.

4. COVID-19 sickens more children than many realize.

According to the CDC, nearly 2 million American children ages 5 to 11 have contracted COVID-19 since the pandemic began, while an additional 1.5 million 12- to 15-year-olds have been infected. While this is a tiny fraction of the tens of millions of cases in adults in the United States, it is still a disease that is more serious and widespread than most others that strike children. Children who are infected with the coronavirus tend to get a more mild case. But even then, being laid up with fever, chills, headache, stomachache, and other symptoms isn’t any kid’s idea of fun. For some children, their bout with COVID-19 is more severe. “Thousands of hospitalizations in this age group have been traumatic and costly,” Moore says. Younger kids are especially prone to a condition called multisystem inflammatory syndrome in children (MIS-C), which can cause heart dysfunction, kidney injury, and, in rare instances, death. The CDC reports more than 600 deaths in kids under 15 due to COVID-19, many from this condition. And an unknown number of children develop a longer-lasting condition that has come to be known as long COVID. One study in Rome published in April 2021 in Acta Paediatrica followed 129 kids (the median age was 11) who had been diagnosed with COVID-19 and found more than half had at least one lingering symptom after their recovery from acute disease. More than 10 percent were still experiencing three or more bothersome symptoms at least four months out. Vaccination can largely prevent this, Moore says. RELATED: What to Do When You and Your Family Fight About COVID-19 Vaccines Measures employed to protect kids from COVID-19 have also impacted their mental health and learning. The KFF survey found nearly one in four parents of a child attending in-person school has had to quarantine their child due to possible exposure during the recent school year, causing them to miss classes. Even more tragic, a study published in October in Pediatrics found 140,000 children have lost a caregiver to the disease. Protecting children and their families with the vaccine will enable them to participate in schooling and social activities without the fear they might get very sick, Dr. Jacobson says. RELATED: Pediatricians Declare Kids’ Mental Health a National Emergency

6. Many pediatricians’ offices will offer COVID-19 vaccines.

Kids get most of their vaccines from their pediatrician’s office, so the federal government has already sent supplies for children 5 to 11 to more than 25,000 pediatricians’ offices. This will enable parents to ask their child’s doctor any questions they have about the shot. In addition, shots for these younger children will be available at hundreds of schools and community-based clinics, hundreds of rural health clinics, more than 100 children’s hospitals, and numerous pharmacies, the federal government said. As with the shots for tweens and teens, they will also be available at many pharmacies. You can find a location offering the shots near you at the government’s website vaccines.gov. All shots are being made available at no cost and regardless of citizenship or insurance status.

7. Younger babies and toddlers could get the nod soon.

Pfizer, Moderna, and Johnson & Johnson are all testing their vaccines in children, including those younger than 5. Clinical trials currently under way by Pfizer, for example, involve preschoolers ages 2 to under 5 as well as babies from 6 months to under 2. Once they have data on the safety, effectiveness, and dosage for those ages, the manufacturers will present it to the FDA and the CDC. It’s unclear whether shots will ever be offered to infants under 6 months old, because their immune system works differently than older children’s. Flu shots, for example, are not given to babies under 6 months because the vaccine offers them no protection.

8. Immunizing children could provide a path out of the pandemic.

The CDC stresses that children should get their COVID-19 vaccine as soon as they are able to protect themselves from this disease and to be able to attend school and social events without the worry they might get seriously ill. Vaccinating children can also help protect parents or siblings who are immunosuppressed from a disease or medication. A Swedish study published in JAMA in October found that families where one member is immunized have up to 61 percent lower risk that others in the home will get the disease. When three or four are vaccinated, there is up to a 94 percent reduction. Some experts also believe that as long as kids are not vaccinated in sufficient numbers, the pandemic will continue as new and more harmful or infectious forms of the coronavirus develop even beyond the highly contagious delta variant. Because children can get the disease and pass it to others, vaccinating children can stop this important chain of transmission. “We’re in a pandemic, and a race against time to control the variant so more don’t have a chance to develop,” Jacobson says. To protect individual children and others in society, he advocates for young patients to get the COVID-19 vaccine, just as they do all shots recommended for children. “I will strongly recommend this vaccine to my patients,” he says.