The approval of Pfizer COVID-19 vaccines for children under five years old hits another delay as the Food and Drug Administration (FDA) needed more data.

On Friday, the FDA said it had been reviewing new trial information that arrived after Pfizer and BioNTech requested emergency authorization in this age group, Reuters reported.

The agency noted that more data is needed before weighing in on the authorization and may take at least two months before it releases its decision on the vaccine, which has a lower dose than the usual jab, for this age group.

The FDA said it needed to wait for data on how well a third shot will work for children under five years old, Associated Press reported. In a statement, Pfizer said it expected the data by early April.

Pfizer and BioNTech have already submitted data on their first two doses of what was planned as a three-dose jab for the said age group. The companies made their move upon the request of the FDA.

"If something does not meet the standard, we can't proceed forward," FDA's Center for Biologics Evaluation and Research director, Dr. Peter Marks, said, adding that he hoped parents would understand the agency's decision.

Marks added that they take their responsibility for reviewing these vaccines "very seriously," noting that they are "parents as well."

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Pfizer COVID-19 Vaccine for Children Under 5 Postponed

Despite the FDA's calls on parents to be patient and understand their decision, some of them were not pleased with the vaccine's postponements for this age group.

Rachel Perera, a mother of an eight-month-old baby from Los Angeles, was one of the parents who hoped that the COVID vaccines for children under five would be administered this winter. However, her hopes will not come true due to the delays.

"I'm just tired, and it feels like 'when is this going to end?... It feels like people around us are moving on with their lives, and we're being left behind," Perera said.

Reuters reported that initially, the FDA planned to make a decision on the vaccine based on early trial data as soon as next week, with the government preparing to roll it out on February 21.

The agency has asked Pfizer to speed up its application as the Omicron variant caused a surge of infections, including among kids.

Although parents were not pleased with the FDA's decision on Friday, vaccine experts were delighted with the agency's move.

Dr. Paul Offit from the Children's Hospital in Philadelphia said the agency's decision on waiting for the safety and efficacy data of all three doses to be available only "makes sense."

"I think they made the right decision to be careful and wait for the third-dose data," former FDA Vaccine Chief Dr. Jesse Goodman said.

CDC Says COVID Booster Shots' Efficacy Wanes

A Centers for Disease Control and Prevention (CDC) study revealed on Friday that the efficacy of the Pfizer and Moderna booster vaccines wanes after four months, New York Post reported.

According to the CDC study, protection against hospitalizations dropped from 91 percent during the first two months following the third dose to 78 percent four months after the shot, U.S. News Reported. However, the research also noted that the protection from the booster shots would only have 37 percent after about five months.

The said study was conducted by CDC with cases across 10 states from August 26 last year to January 22 this year. The CDC then recommended that eligible individuals "remain up to date with recommended COVID-19 vaccinations" to protect themselves from the coronavirus.

READ MORE: CDC Recommends Pfizer COVID Vaccine Boosters for Children as Young as 12

This article is owned by Latin Post.

Written by: Joshua Summers

WATCH: FDA Delays Approval of Pfizer's COVID-19 Vaccine for Children Under 5 - From PBS NewsHour