Families deciding between the two COVID-19 vaccine alternatives for young children soon will have a choice between faster protection or a more comprehensive immune response.

Both options should offer effective and safe protection against serious illness or death.

“That’s what you care about,” said Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia. “That’s what you’re trying to do.”

He was a member of the independent advisory panel for the Food and Drug Administration that unanimously recommended Wednesday approval of two options for children under 5 years of age — one from Moderna and the other from Pfizer-BioNTech. Infants, toddlers, and preschoolers could get access to a COVID vaccine as soon as the beginning of next week, more than a year and a half after the first adult vaccines became available.

The Moderna vaccine for young children is administered in two doses, each given four weeks apart. The Pfizer vaccine is a three-shot series. The first two Pfizer shots are administered over three weeks, but they are only minimally effective until an additional dose is given after another two months.

The difference has to do with the dose concentrations: Moderna’s shots each deliver 25 micrograms of vaccines. Pfizer’s much smaller dose, just three micrograms, resulted in the need for an additional shot.

So the Moderna shots can offer their full potency sooner. The benefit of the Pfizer series is that third shot makes it more effective at protecting against the omicron variant, versions of which are the most common COVID strains circulating right now, Offit said.

» READ MORE: Kids under 5 should soon have access to COVID vaccines, but many parents are likely to say, ‘I don’t feel comfortable’

Children who get the Moderna vaccine likely will need a booster shot in about four months, noted Offit. A fourth dose of the Pfizer vaccine may also be needed by children who receive that brand, according to discussions by the FDA advisory panel.

The advisory panel’s non-binding recommendation is an important step in the process of getting doses into the arms of kids younger than 5 years old. The FDA and Centers for Disease Control and Prevention are expected to finalize approval in the coming days.

Protecting young children from COVID

While children are far less likely to develop serious illness or die from COVID, the virus has proven more dangerous to them than common illnesses like the flu. More than 1,250 people 18 or younger have died of COVID since the beginning of the pandemic, the CDC has reported.

In its discussions, the advisory panel saw data that more children were hospitalized for COVID infections during this winter’s omicron wave than at any previous point in the pandemic. Nearly two-thirds of children four or younger hospitalized with COVID had no underlying conditions, according to data shared by Moderna.

“We have to be careful that we don’t become numb to the number of pediatric deaths because of the overwhelming number of older deaths,” said Peter Marks, the FDA’s director of the Center of Biologics Evaluation and Research, during the meeting. “Vaccine-preventable deaths are ones that we would like to try to do something about.”

Some parents can’t wait to get their children the shots.

“I feel excited, relieved, still honestly frustrated that it’s taken this long,” said Zachary Risler, an emergency room physician from Philadelphia with three children — two of them under 5.

His work as a doctor has made him constantly nervous about bringing COVID home to his unvaccinated children, he said.

DeMauri Mackie, of Elkins Park, is eager to get the shots for her 3-year-old, Talia Wilkowski. The higher concentration of each Moderna shot was appealing, Mackie said, after more than two years of limiting her daughter’s activities dues to COVID concerns.

“She hasn’t been inside a store in two years. We don’t take her on errands,” said Mackie, a health outcomes researcher. “She hasn’t really been inside buildings other than her school and our home in over two years.”

» READ MORE: A COVID-19 vaccine for kids under 5 is likely to be approved soon, but there may be a lag before they’re in your doctors’ office

Deciding between vaccine options

Each Pfizer and Moderna shot contains lower dosages than administered to adults and older children in an effort to balance effectiveness with potential side effects. If the doses are too small, the immune response is too weak. Larger doses, though, can cause more intense side effects, noted Offit, the CHOP expert advising the FDA.

The FDA advisory panel focused on the frequency of fevers, a particular concern in young children, and found about a quarter of children who received the Moderna vaccine reported fevers — particularly after the second dose. Rarely, the panel reported, those fevers reached 104 degrees Fahrenheit.

Each Pfizer dose was far less likely to cause side effects, with reactions like fever, fatigue, and diarrhea similar to placebo rates among children 2 to 4.

The Pfizer vaccine is about 80% effective at preventing any illness. The Moderna vaccine is about 51% effective at preventing mild illness for children 2 and younger, and 37% effective for children between ages 3 and 5.

These rates signal that the vaccines are highly effective at preventing serious illness, Offit said.

“To try and expect that you’re going to get protection against mild illness is fanciful,” he said. “We’re going to be living with mild illness with this vaccine for decades.”

Finding vaccines for little kids

Children younger than three won’t be able to get their shots at a pharmacy, so parents will likely need to rely on doctors offices and clinics for their doses. Not all pediatricians will be carrying the vaccine, though. About 70% of the 1,290 Pennsylvania providers participating in a federal children’s vaccination program, and 64% of the 925 New Jersey providers, are registered to carry COVID vaccines for children.

The Philadelphia Department of Public Health said earlier this week that some doctors’ offices were likely waiting until after Wednesday’s hearings before ordering deliveries of doses for children, meaning all providers may not have doses as soon as they are approved.

The delay may extend to doctors’ offices nationally, said Ada Stewart, board chair of the American Academy of Family Physicians. But it should last no more than a week.

Pediatricians are more worried about the number of parents who are reluctant to get their children vaccinated. A May survey from Kaiser Family Foundation found more than a third of parents planned to see how other children responded before getting doses for their kids.

“I’m going to tell my patients this is safe and effective,” said Stewart, a physician who practices medicine in Columbia, S.C. “This is a way to protect your child from dying.”