mRNA Vaccine Produces Immune and T-cell Response

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Preliminary data from a German Phase I/II trial shows Pfizer/BioNTech COVID-19 vaccine candidate produces immune response.

Pfizer and BioNTech SE announced that initial data from an ongoing German Phase I/II clinical trial that showed that the mRNA-based vaccine candidate against SARS-CoV-2 elicited high SARS-CoV-2 neutralizing titers and demonstrated a concurrent induction of high level CD4+ and CD8+ T cell responses against the SARS-CoV-2 receptor binding domain (RBD) antigen compared to baseline.

The results suggested that BNT162b1 could potentially be administered safely, with a manageable tolerability profile, the companies reported in a July 20, 2020 press statement.

Local reactions and systemic events after immunization were dose-dependent and were generally mild to moderate and transient; occasional severe adverse events such as flu-like symptoms and injection site reactions resolved spontaneously or could be managed with simple measures. No serious adverse events were reported, according to the statement.

The vaccine candidate is a lipid nanoparticle formulated, nucleoside-modified messenger RNA that encodes an optimized SARS-CoV-2 RBD antigen.

The trial involved 60 healthy adults 18–55 years of age receiving one of five different dose levels. The vaccine produced high, dose level-dependent SARS-CoV-2-neutralizing titers and RBD-binding IgG concentrations after the second dose, the companies reported.


The data were released on an online preprint server and are undergoing scientific peer-review for potential publication.

Preliminary data from the German and US Phase 1/2 studies, along with preclinical and other data, will be used to establish a dose level for a global Phase 2b/3 safety and efficacy trial of up to 30,000 healthy participants. This trial is anticipated to begin in late July 2020, pending regulatory approval.

Source: Pfizer