The ongoing U.S. Phase 1/2 randomized, placebo-controlled, observer-blinded study is evaluating the safety, tolerability, and immunogenicity of escalating dose levels of BNT162b1. The initial part of the study included 45 healthy adults 18 to 55 years of age. Preliminary data for BNT162b1 was evaluated for 24 subjects who received two injections of 10 µg and 30 µg, 12 subjects who received a single injection of 100 µg, and 9 subjects who received 2 doses of placebo control.
The participants received two doses, 21 days apart, of placebo, 10 µg or 30 µg of BNT162b1, or received a single dose of 100 µg of the vaccine candidate. Because of a strong vaccine booster effect, the highest neutralizing titers were observed seven days after the second dose of 10 µg or 30 µg on day 28 after vaccination. The neutralizing GMTs were 168 and 267 for the 10 µg and 30 µg dose levels, respectively, corresponding to 1.8- and 2.8-times the neutralizing GMT of 94 observed in a panel of 38 sera from subjects who had contracted *redacted*.
At the 10 µg or 30 µg dose levels, adverse reactions, including low grade fever, were more common after the second dose than the first dose. Following dose 2, 8.3% of participants who received 10 µg and 75.0% of participants who received 30 µg BNT162b1 reported fever ≥ 38.0 °C. Local reactions and systemic events after injection with 10 µg and 30 µg of BNT162b1 were dose-dependent, generally mild to moderate, and transient. The most commonly reported local reaction was injection site pain, which was mild to moderate, except in one of 12 subjects who received a 100 µg dose, which was severe. No serious adverse events were reported. Given higher numbers of subjects experiencing local reactions and systemic events after a single 100 µg dose with no significant increases in immunogenicity compared to the 30 µg dose level, the 12 participants in the 100 µg group were not administered a second dose.
In all 24 subjects who received 2 vaccinations at 10 µg and 30 µg dose levels of BNT162b1, elevation of RBD-binding IgG concentrations was observed after the second injection with respective GMCs of 4,813 units/ml and 27,872 units/ml at day 28, seven days after immunization. These concentrations are 8- and 46.3-times the GMC of 602 units/ml in a panel of 38 sera from subjects who had contracted *redacted*.
The BNT162b1 candidate remains under clinical study and is not currently approved for distribution anywhere in the world. If the ongoing studies are successful and the vaccine candidate receives regulatory approval, the companies expect to manufacture up to 100 million doses by the end of 2020 and potentially more than 1.2 billion doses by the end of 2021.