Pfizer and BioNTech have initiated a Phase II/III clinical trial of their second Covid-19 vaccine candidate, BNT162b2, at a 30µg dose level in a two-dose regimen.

The trial is being conducted globally but will not include China.

BNT162b2 is a single nucleoside-modified messenger RNA (modRNA) candidate that encodes an optimised SARS-CoV-2 full length spike glycoprotein (S).

The companies decided to advance the vaccine candidate into the trial based on a review of preclinical and clinical data from Phase I/II studies and consultation with the US Food and Drug Administration (FDA) and other global regulators.

Pfizer Vaccine Research & Development senior vice-president and head Kathrin Jansen said: “Our selection of the BNT162b2 vaccine candidate and its advancement into a Phase II/III study are the culmination of an extensive, collaborative, and unprecedented R&D program involving Pfizer, BioNTech, clinical investigators, and study participants with a singular focus of developing a safe and effective Covid-19 RNA vaccine.

“The Phase II/III study protocol follows all the FDA guidance on clinical trial design for Covid-19 vaccine studies.”

The event-driven, randomised, observer-blinded Phase II/III trial is designed to enrol up to 30,000 participants aged 18 to 85. It will compare the safety, immune response, and efficacy of BNT162b2 to that of placebo.

The trial’s primary endpoints will be the prevention of Covid-19 in people not infected by SARS-CoV-2 before immunisation, and prevention of the disease irrespective of previous infection status.

Secondary endpoints involve prevention of severe Covid-19 in those groups. The study will further assess prevention of infection by SARS-CoV-2.

The trial’s primary efficacy analysis will be based on the number of subjects with symptomatic Covid-19.

By the time of completion, the Phase II/III trial is expected to be active at around 120 sites worldwide, including 39 states in the US.

The companies’ first Covid-19 vaccine candidate is already undergoing clinical trials.

This Phase II/III trial follows the Phase III study of Moderna’s Covid-19 vaccine candidate, mRNA-1273.