Pfizer and BioNTech have commenced a Phase 1/2/3 trial to evaluate the safety, tolerability, and immunogenicity of their Covid-19 vaccine BNT162b2 in children, aged below 12 years.

Phase 1 of the trial will be an open-label dose-finding study, evaluating two-dose BNT162b2 vaccine, administered 21 days apart, in three age groups.

The three age groups include children aged five to 12 years, two to five years, and six months to two years, according to the US National Library of Medicine’s clinical trials website.

Also, the clinical trial will evaluate three dosing levels of the mRNA-based vaccine, including a 10mcg low-dose level, 20mcg mid-dose level, and a 30mcg high-dose level.

The Phase 1 study is designed to identify the preferred dose level of BNT162b2 from up to 3 different dose levels in each age group.

The preferred dose level selected from the Phase 1 trial will be evaluated in the Phase 2/3 trial, a placebo-controlled, observer-blinded study.

The Phase 2/3 study will evaluate the vaccine efficacy across all age groups in which immunobridging is successful, based on the accrual of cases across those age groups.

All the study participants will have blood drawn at baseline prior to Dose 1 and 6 months after Dose 2 vaccination.

The persistence of the immune response will be assessed based on immunogenicity data collected in participants at baseline and at 1, 6, 12, and 24 months after Dose 2.

Also, the clinical trial will assess the efficacy of the vaccine against confirmed Covid-19 and against asymptomatic infection.

According to the study protocol, all the study participants will be unblinded at the 6-month follow-up visit, and those who received a placebo will be offered to receive BNT162b2.

Furthermore, all the estimated 4,500 participants in the study will contribute to the VE analysis for conditional VE and asymptomatic infection.

Last month, Pfizer and BioNTech have started a global Phase 2/3 study to further evaluate their Covid-19 vaccine candidate in healthy pregnant women.