Dr. Peter Marks, the Food and Drug Administration's vaccine chief, said he is well aware that COVID-19 booster uptake might be low for the latest shot, authorized by the government on Thursday morning for young children over 6 months old, but he told ABC News that he's hopeful increased access may also lead to some kids getting greater protection against the virus ahead of the winter, when infections can be more likely.
The updated bivalent booster that targets multiple newer strains of the virus, will likely be available early next week for the youngest children, Marks said in an interview. That age group is the last to become eligible for the new booster.
So far, according to the Centers for Disease Control and Prevention, less than 10% of kids under 5 have gotten their initial COVID-19 vaccines -- which means there's a very small pool of children who are even eligible for boosters. But Marks hopes that those vaccinated children will soon get their boosters, and unvaccinated children will be encouraged to get their first series.
"The whole point of today's action was to ensure that those parents who have decided to take advantage of the fact that we do have a vaccine that can help prevent the worst outcomes from COVID-19, such as hospitalization and death ... could have the benefit of having the most up-to-date version of the vaccine, which is the bivalent vaccine," Marks said.
"Hopefully this is also an opportunity that the 90% of parents who have not vaccinated their children in this age range will consider doing so. Because not being vaccinated at all puts one at risk for the worst outcomes from COVID-19," he added.
Under the new authorization, children under 6 who received the Moderna vaccine can get a bivalent booster at least two months after their first series of shots.
For children under 5 who received the Pfizer vaccine, it's slightly different: Kids can get the newly authorized bivalent booster in place of the third shot in the Pfizer series for young kids. And going forward, any young child who gets the three-shot Pfizer series will get two primary shots and then the bivalent booster.
On a larger scale, vaccine uptake for the youngest age group has traditionally been far lower than other groups throughout the pandemic.
And even for older age groups, booster uptake has been very low over the three months that bivalent shots have been on the market.
According to the CDC, just under 13% of people over 5 years old have gotten a bivalent booster. The rate is highest for people over 65, for whom around one-third have been boosted.
Everyone over age 12 became eligible for bivalent boosters in September, so long as it had been three months since their last vaccine. Then in October, the eligibility expanded to everyone over age 5.
And now, in December, babies as young as 6 months old are eligible as well.
Public health officials have long hoped that the arrival of cold weather and flu season would give people a natural push to get up-to-date on both their flu vaccines and their COVID-19 boosters.
But that bump in COVID-19 shots hasn't quite materialized, Marks acknowledged, and he's not sure that uptake will budge all that much over this winter season -- despite his avid recommendations.
"I don't quite fully understand why there's significant hesitancy to get the bivalent boosters. I think I'm the first to acknowledge that these vaccines are not perfect. They're not going to give you 100% protection against COVID-19. And perhaps because people have heard, 'Well, I got the booster but I got COVID,' there's some skepticism there," Marks said.
But inoculation will still cut down on the chances of contracting the virus and keep people out of the hospital, he said.
"Even if it's not perfect -- it's the best you can do," Marks said. "I will repeat something that has done me well to date, which is perfection is the enemy of good."
Marks particularly encouraged getting vaccinated and boosted ahead of the winter season, when he predicted that cases were likely to go up and hospitals could be strained from the combination of heavy RSV and flu cases.
Already, wastewater surveillance systems across the country have begun to pick up upticks in COVID-19 cases, and Marks called the increasing slope of cases "disturbing."
"From what I can see happening over the recent past, I think the good news is, we're not likely to see the number of deaths that we've seen in previous winters. The part that is concerning is that we could see a large number of cases," he said.
"We're also seeing hospitalizations rise significantly and deaths, which had been declining, are starting to increase again. Once people see that, my guess is that will drive them to potentially consider this," Marks said. "Though I wouldn't wait for that."