The Pfizer-BioNTech vaccine to protect against COVID-19 was made available for adults at the end of 2020.
Almost a year later, teens are able to be vaccinated, but children ages 5-11 still are waiting their turn.
"It's a pretty complex process," said David Matthews, a pharmacist at Shoreline Pharmacy.
Accurately figuring out vaccine dosages for children doesn't work the same way as adjusting a medication dosage, he said. With medicines, sometimes you can just adjust the adult dose.
"Vaccines are completely different than that," he said. "There are some vaccines that the dose is exactly the same, but for the COVID-19 dosing and the flu vaccine, they’re not the same. And the COVID-19 -- they’re still . . . doing studies and stuff for the pediatrics, because it is so different."
People tend to think of children as being short adults, said Driscoll Children's Hospital Infectious Diseases Specialist Dr. Jaime Fergie. They're not, physiologically. Their bodies process things differently.
"We have to study vaccines and medicines in children to find out. . . . if they have (an) adverse reaction in the young kids that we don't see in the rest of the populations. So we have to study them. We cannot just assume that everything is going to be the same."
Which is why the FDA authorization process for each age range is a fresh one; because the vaccine works differently with that age's level of physical development.
"So they have to prove efficacy first, which means 'Does it work?' ” Matthews said. "And then after they prove efficacy, they have to drill down further and try different doses to make sure that it will work at different amounts of drug given. The optimum dose."
The original vaccine is tested on adults, the version for 12-18 year olds was tested on that specific age group, and now clinical trials are being conducted on 5-11 year olds.
"So that’s why it’s taking longer to develop it -- because they also have longer study time," Matthews said. "It’s harder to get pediatrics enrolled. It takes them longer to enroll the number of patients that it takes to get a good, statistically significant sample size of the patients because not everybody’s gonna let their children be vaccinated."
When the first wave of the novel coronavirus made its way around the Coastal Bend, children were largely spared from infection. But Matthews and Fergie both said the Delta variant changed that.
"Still they do well," Fergie said. "Clearly, still, most of them recover well, but some -- some don't."
And whereas adults can be helped with monoclonal antibody infusion treatments, that option isn't available for children younger than 12.
And the recently discovered Mu variant could prove worse than Delta.
"We don't know, but we think it's going to be even more virulent in children, in others words, more able to cause disease in children," Matthews said. "But we're not 100 percent sure of that. Early studies suggest that that might be true."
Whether that proves to be true or not, Fergie, the pediatrict specialist, said not vaccinating eligible children is a mistake.
"Once it's available, of course, we need to encourage parents to vaccinate their children," he said.