Children’s Hospital Colorado Leads Phase 1 COVID-19 Vaccine Study for Participants 6 months to 11 Years in Age

Children’s Hospital Colorado Leads Phase 1 COVID-19 Vaccine Study for Participants 6 months to 11 Years in Age

Studies continue onward, paving the way for COVID-19 vaccination of children under 12. As TrialSite has showcased, various trial sites on the frontlines of the war on COVID-19 are conducting initial Phase 1 safety and dosing studies, which lead to Phase 2 and ultimately pivotal Phase 3 trial. This leads to either acceptance under emergency use authorization or a full marketing authorization application to the U.S. Food and Drug Administration (FDA). The rationale for vaccinating young children centers on three arguments, including 1) disease transmission prevention, 2) safety measure to better ensure a child doesn’t become severely ill from the coronavirus, and 3) social integration as various governments have established policies that children must be masked in some locations, or remain in social distance mode, etc. In Colorado, the Pfizer-sponsored study is conducted at Children’s Hospital Colorado on the Anschutz Medical Campus where, this summer, physicians are evaluating the vaccine’s impact on children aged 5 to 11. As the study progresses, the study team will test the vaccine on babies and children from 6 months to 4 years of age. This is a closely monitored study for a number of reasons including the ultimate goal of society-wide vaccination to eradicate COVID-19. A pediatric infectious disease expert, Dr. Eric Simoes, serves as principal investigator for this closely watched clinical trial.

Full throttle mass vaccination, along with the development of therapies and appropriate social and public health measures are a centerpiece to America’s eradication of COVID-19, a pandemic that’s taken over 612,000 lives now in the U.S. alone, and over 3.7 million worldwide.

Rocky Mountain Demand for Study Participation

According to a recent entry from the University of Colorado Health (UC Health), vaccination for children here in the Mile High State is so much in demand that study sponsor Pfizer created a website allowing parents of the children to sign their children up as prospective volunteers. The website can be accessed here.

Nationwide, the study involves approximately 80 trial sites with a total of 4,600 volunteer children. At the Children’s Hospital of Colorado site, the study team is expected to enroll approximately 250 children.

As populations considered underserved or underrepresented center on primarily minorities in relation to the Pfizer child study, the study team continues to emphasize diversity and health equity, as well as equitable participation in the vaccination research.  

Research Equity

Denver metro area’s 3 million people is about 22% Latino representing over 610,000 Latinos while the Black population, notably lower than many cities back east, is higher than most other cities in the west except for the coasts.  The Denver area represents one of the larger Latino or Hispanic populations in America. Blacks make up about 10% of the city of Denver, and its Five Points district has been referred to as Harlem of the West in days past.  

The Denver metro area also includes a sizable Asian population, and Colorado is home to a considerable Native American population particularly in the southwest parts of the state, which abuts the massive Navajo Nation.

Children’s Hospital Colorado staff understand that Blacks, Latinos, and other ethnic or racial minorities typically do not participate in research as much as whites do. Dr. Simoes reminded all that “The groups that have been particularly affected throughout the pandemic have been minority populations,” Simoes said. “We’ve done a lot of outreach to different minority populations: Black Americans, Latin Americans, and Asians.”

Principal Investigators: Urgent Need for Vaccination

The principal investigators from here in Denver, including Dr. Simoes and Dr. Lalit Bajaj, a pediatric emergency specialist emphasize that they expect the vaccines to work well, just like in adults.  The study will commence soon and upon start-up the child participants will receive their first dose and second doses of vaccine, or placebo three weeks apart just as is the case with adults. 

The doctors went on the record that the coronavirus is afflicting younger people and they know from experience that children are at risk. Dr. Bajaj commented for UC Health, “We see kids sick with COVID-19” and emphasized that “Some of these children are very, very sick. There’s an impact on the patients themselves and on the community as a whole.”

Possibly the most compelling reason shared in the UCHealth article authored by Katie Kerwin McCrimmon centers on the fact that the recent variants of SARS-CoV-2 are “highly transmissible, meaning they spread very easily, especially in children.”

Simoes is confident that the clinical trials will prove that the vaccines are as safe for young children as they are for teens and adults.

“There is no reason to think that something unsafe is going to happen when children receive vaccines,” Simoes said. “These vaccines appear to be very safe.”

The Study

The Phase 1 and 2 study (NCT04816643) targets a total of 4,644 participants in three different age groups, including as low as 6 months to 2 years of age. The Phase 1 part is an open-label dose-finding study seeking to evaluate the safety, tolerability, and immunogenicity of the investigational vaccine under FDA emergency use authorization known as BNT162b2 or “Comirnaty.”  The study involves two doses scheduled again in three age groups.

Dose finding, that is, experimenting to find the optimal dose for safety and immunogenicity, is initiated first in the study participants from 5 to 12 years of age based on the acceptable blinded safety assessment of the 30 dose in 12 to 15 years old in a previous study, which led to the FDA giving the nod for emergency use authorization. So, in summary, the Phase 1 part of the study helps the study team and pharmaceutical company, in this case Pfizer, to help identify the optimal or “preferred dose level(s)” of the investigational product from up to 3 varying dose levels in each age group.

Thereafter, the Phase 2 and then 3 studies will serve to evaluate safety, tolerability, and immunogenicity in each age group at the selected dose level from Phase 1. The overall efficacy of the Pfizer vaccine is evaluated across all age groups, in which so-called “immunobridging” is successful, however, this is contingent on the accrual of enough COVID-19 cases across the age groups.

The Vaccine in Use under EUA & Not FDA Approved

The Pfizer vaccine (and all of those currently targeting COVID-19 in the United States) isn’t FDA approved but rather is in use under the emergency use authorization (EUA) use category. As the FDA shared on their website, this means that after a careful analysis of risks and benefits, the Gold Standard regulatory body determined that the benefits, considering the ongoing pandemic, outweigh any risks. That is, the agency makes the product available even though it’s still considered investigational (e.g. not approved) based on the best available evidence.

More information on the investigational product can be reviewed here. While a number of issues have been reported or written about (check TrialSite for COVID-19 vaccine safety), thus far, the overwhelming consensus among leading government agencies, research institutes, and the medical community is that the benefits of the vaccines currently under emergency use authorization far outweigh the risks.

About Children’s Hospital Colorado 

Based in the metropolitan Denver area, Children’s Hospital Colorado is an academic pediatric acute care children’s hospital located in the Anschutz Medical Campus in Aurora, Colorado. This hospital maintains 434 pediatric beds at the main Aurora campus. A teaching hospital, Children’s Hospital Colorado operates a number of residency programs. The hospital is affiliated with the University of Colorado Denver School of Medicine and provides comprehensive specialties and subspecialties to infants, children, teens and young adults aged 0-21 and at times till 25 throughout not only Colorado but also a large region covering both the Midwest, part of the western plains and the Rocky Mountain region.

Lead Research/Investigator

Eric Simoes, MD, Co-Director, Maternal and Child Health Initiative, Center for Global Health, Children’s Hospital Colorado

Lalit Bajaj, MD, MPH, MSPH, Associate Professor Pediatrics


  1. Colorado may be gripped by panic. Of all humanity, children this young are at orders of magnitude less risk. Very few of them even get this virus, almost none of them die from it, and a very small number of those who do get sick from it suffer long term complications. Let them catch it if they do, and give them treatment. Let them acquire natural immunity. Vaccinating them is foolish and carries some risk. Donating your child to be experimented on in a trial is heartless sadistic child abuse.