On June 18, the Centers for Disease Control and Prevention (CDC) endorsed COVID-19  vaccines for young children who are at least 6 months old to age five, says Stanford Medicine. This means roughly 20 million children under the age of six are newly eligible for vaccination.

Since the beginning of the pandemic, there have been over 2 million cases, 20,000 hospitalizations and 200 deaths due to COVID-19 in children under 5 years of age.  Now, parents have a choice of giving their children in that age group either the Pfizer/BioNTech or the Moderna vaccine and they may be wondering which option is preferrable.

According to CNN, both vaccines use an mRNA platform and are well tolerated and safe.

“I think they are both highly efficacious with great side effect profiles and I would not hesitate to give my kids either,” said Dr. Nina Alfieri, a pediatrician at Ann & Robert H. Lurie Children’s Hospital of Chicago. “I think both are really good options.”

Experts say there are subtle differences between the two vaccines. Moderna’s shot is authorized for children who are 6 months through 5 years of age. Pfizer’s is for kids 6 months through 4 years old. Pfizer’s vaccine was previously authorized for children 5 years and older, making it the only choice for that age group until the Food and Drug Administration (FDA) recently approved the Moderna shot for those 6 through 17 years of age. The CDC then also recommend it last week.

Children under the age of 5 are now eligible for either the Pfizer three-dose vaccine at a 3-microgram dose or the two-dose Moderna vaccine which is a 25-microgram dose, says Dr. Grace Lee, an expert in pediatric infectious disease at Stanford Children’s Health.

Because of the smaller dosage in the Pfizer vaccine, three shots were needed to offer protection, says STAT News. The first two doses are given 21 days apart and the third dose is given at least eight weeks after the second dose, so the interval to complete the series of vaccines will be 11 weeks.

Moderna, on the other hand has a stronger dose and shots are given four weeks apart after which a child would be termed fully vaccinated or up to date on the COVID-19 vaccines.

“Children who are moderately or severely immunocompromised may need additional doses,” says Lee.

So, the differences between the two vaccines is that there will be fewer trips to the doctor, pharmacy or clinic to complete the primary vaccine series and the child will have quicker protection with Moderna. However, the side effects from Moderna may be harsher. Children will also be slightly more prone to develop a fever, say experts, who assure parents that the fever doesn’t cause any permanent damage or long-term problems and can be managed by over-the-counter medicine like Tylenol or Motrin.

The big drawback with the Pfizer vaccine is that it takes three visits and will take nearly three months to get a child fully vaccinated.

Both the FDA and the CDC found that potential side effects from both vaccines were mild and short-lived. They included pain and swelling at the injection site, fatigue and sleeplessness, fussiness, and loss of appetite.

As far as effectiveness of the vaccine, studies found that the omicron variant was successful in partially evading the protection offered by either company’s vaccine. Moderna was estimated to be 36.8% effective against symptomatic disease for kids 2-to-5 years of age and 50.6% protective against symptomatic disease for those 6-to-23 months old, says CNN. Data from Pfizer was inconclusive as only 10 COVID-19 cases developed during clinical trials in the vaccinated and placebo groups — too small a number to estimate efficacy ─ but the company issued a press release saying preliminary findings were “encouraging.”

The bottom line is to get vaccinated, say experts.

“I do not think it’s clear that one is any better than the other. They are different,” says Paulsen. “It is very much what the parents prefer. Balancing those differences as well as, honestly, what’s available and what their pediatrician has, or what the local hospital has.”

Some clinics may not offer vaccines for small children. CVS stores that have MinuteClinics will vaccinate this new age group but only if the child is 18 months and older. Check Vaccines.gov for help in finding suitable clinics near you.