On Jul. 20, 2020, Pfizer and BioNTech announced initial data from their ongoing German Phase 1/2, open-label, non-randomized, non-placebo-controlled, dose-escalation trial, that is part of the global mRNA-based vaccine program against SARS-CoV-2. The data are available on an online preprint server at medrxiv and are concurrently undergoing scientific peer-review for potential publication.

The preliminary clinical results are for the most advanced investigational vaccine candidate in Pfizer’s and BioNTech’s BNT162 mRNA-based vaccine program against SARS-CoV-2, BNT162b1. This vaccine candidate is a lipid nanoparticle formulated, nucleoside-modified messenger RNA that encodes an optimized SARS-CoV-2 receptor binding domain (RBD) antigen. Overall, the new preliminary data from this German study support and expand upon the recently disclosed early results from the corresponding U.S. trial with BNT162b1.

Preliminary data for BNT162b1 in the German Phase 1/2 trial were evaluated with a total of 60 healthy adults 18 to 55 years of age enrolled in the study. Of these 60 participants, 12 subjects per dose level (1 µg, 10 µg, 30 µg, and 50 µg; 48 participants in total) were vaccinated with BNT162b1 on day 1 and day 22 (n=12 per prime-boost cohort, except n=11 for the 10 µg and 50 µg cohorts from day 22 on). Furthermore, 12 participants received a single injection of 60 µg.

The vaccine elicited high, dose level-dependent SARS-CoV-2-neutralizing titers and RBD-binding IgG concentrations after the second dose. Day 43 SARS-CoV-2 neutralizing geometric mean titers were in the range of 0.7-fold (1 µg) to 3.2-fold (50 µg) compared to that of a panel of SARS-CoV-2 infection convalescent human sera. Furthermore, sera of vaccinated subjects displayed broadly neutralizing activity in pseudovirus neutralization assays across a panel of sixteen SARS-CoV-2 RBD variants represented in publicly available SARS-CoV-2 sequences and against the newly dominant D614G strain.

In addition, the initial German trial results demonstrate, for the first time for the BNT62b1 candidate, a concurrent induction of high level CD4⁺ and CD8⁺ T cell responses against the SARS-CoV-2 RBD.