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Results from a Phase 1/2 study of COVID-19 RNA vaccine candidate, BNT162b1, support its safety and immunogenicity. The observer-blinded study involved 45 healthy adults aged 18 to 55 years, randomized to receive either 10 μg, 30 μg, 100 μg of vaccine, or placebo. BNT162b1 involves nucleoside-modified messenger RNA that encodes the receptor-binding domain (RBD) of the SARS-Cov-2 spike protein as the target antigen. The vaccine is formulated in lipid nanoparticles for efficient delivery into cells.
Participants who received 10 μg or 30 μg of the vaccine on Day 1 received a second dose on Day 21; those who received 100 μg did not receive a second dose. The most common symptoms following vaccination were transient pain, fatigue, and headache, which increased with dose level and were reported by more participants after a second dose. RBD-binding Immunoglobulin G (IgG) concentrations were detected at Day 21 for all doses and increased by Day 28 for those who received a second dose. Neutralization titers were measurable at Day 21 for all doses, and increased to substantial levels by Day 28 relative to a panel of COVID-19 convalescent human sera.
The researchers hope to continue testing BNT162b1 with a more diverse sample of participants.