Stating that its Covid-19 vaccine is effective in children aged six and younger, American pharmaceutical firm Moderna has said that it will soon seek regulatory authorisation for it in the US and Europe.
Moderna said it would ask regulators to approve two small-dose shots, as the vaccine generated a similar immune response to adults in its clinical trial.
If authorised, Moderna's vaccine could be the first authorized shot for children under the age of 5 in the United States, and many parents of young children have been waiting on a vaccine.
The nation’s 18 million children under 5 are the only age group not yet eligible for vaccination. Competitor Pfizer currently offers kid-sized doses for school-age children and full-strength shots for those 12 and older.
How effective is the Moderna vaccine?
The Omicron variant of Covid-19 was predominant during Moderna's pediatric trial, and the drugmaker said two doses were around 38% effective in preventing infections in 2 to 5-year-olds and 44% effective for children 6 months to under 2 years old.
It said these figures were consistent with the lower effectiveness against Omicron seen in adults who had received two doses of its vaccine.
There were no severe cases in Moderna's pediatric trial for either vaccine or placebo participants.
Moderna said the shots, spaced four weeks apart, were generally well-tolerated in the age group and the majority of side effects experienced were mild or moderate.
The company enrolled about 6,900 tots and the dose size tested was 25 micrograms - a quarter of the dose that adults receive for each of their first two shots.
There have been some concerns about the size of the dose. By comparison, the dosage of Pfizer and BioNTech's vaccine - which uses similar messenger RNA technology - was 10 micrograms for 5 to 11-year-olds. They are testing 3 microgram doses for children younger than 5.
Authorisation for vaccine
Once Moderna submits the data to the FDA, regulators will debate whether to authorize emergency use of the small doses for tots. If so, the Centers for Disease Control and Prevention then will decide whether to recommend them.
The company is also seeking to have larger-dose shots cleared for older children and teens in the US. Moderna says its original adult dose – two 100-microgram shots – is safe and effective in 12- to 17-year-olds.
But the FDA never ruled on Moderna’s application for teen shots because of concern about a very rare side effect. Heart inflammation sometimes occurs in teens and young adults, mostly males, after receiving either the Pfizer or Moderna vaccines. Moderna is getting extra scrutiny because its shots are a far higher dose.
The risk also seems linked to puberty, and regulators in Canada, Europe and elsewhere recently expanded Moderna vaccinations to kids as young as 6.
“That concern has not been seen in the younger children," said Dr Bill Muller of Northwestern University, an investigator in Moderna’s pediatric studies.
