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Phase 1/2 Study to Describe the Safety and Immunogenicity of a COVID-19 RNA Vaccine Candidate (BNT162b1) in Adults 18 to 55 Years of Age: Interim Report

Our take —

This report of a Phase 1 vaccine study was available as a preprint and was thus not yet peer reviewed. This was a randomized, placebo-controlled study that provided encouraging preliminary evidence that the COVID-19 RNA vaccine candidate (BNT162b1) is well tolerated and elicits an immune response at least comparable to antibody levels observed in a panel of convalescent plasma. This study suggests that a 10ug – 30ug dose of this vaccine candidate could be effective. Participant numbers were limited. Larger Phase 2 and Phase 3 trials are still required to fully evaluate the efficacy of this vaccine candidate. Additionally, continued monitoring of participants will be done to evaluate safety and immune response over time.

Updated Review Available

This expert summary is for the non peer-reviewed preprint. We also summarized this paper after it underwent peer-review and was published in Nature on August 11, 2020. You can find our updated review of the published article here.

Study design

Randomized Controlled Trial

Study population and setting

Phase 1/2 placebo-controlled, observer-blind study to determine the best dose of vaccine candidate BNT162b1 based on safety, tolerability, immunogenicity and potential efficacy. Among 45 participants enrolled and randomized, most were white (82.2.%) or non-Hispanic/non-Latino (93.3%), healthy males (51.1%) or non-pregnant females (48.9%) aged 18-55 years. Twelve participants received either a 10ug or 30ug vaccine dose on days 1 and 21. An additional twelve participants received a single dose of 100ug of vaccine, and 9 received the placebo.

Summary of Main Findings

The safety and tolerability profile of this vaccines is similar to that seen with other RNA-based vaccines, including pain at the injection site, mild to moderate fatigue, headache, and fever. Based on the reactogenicity of the first dose of 100ug, a second dose was not administered. Adverse events were reported by 50% of people in the 10ug and 30ug dose group, and by 58.3% of participants in the 100ug group. No severe adverse advents were reported. Serum antibody titers in all groups were significantly higher than those seen in a panel of COVID-19 convalescent human sera by 21 days post vaccination. Neutralizing antibody titers in all groups were 1.8-2.8-fold higher than those in a panel of COVID-19 convalescent human sera. This study suggests that a 10ug – 30ug dose of this vaccine candidate could be effective.

Study Strengths

This study was placebo controlled, participants were randomized to the different treatment arms and monitored for appropriate markers for safety and tolerability. Comparison of antibody titers is helpful for understanding the magnitude of the immune response elicited by the vaccine candidate.

Limitations

There is no known correlate of protection for SARS-CoV-2 infection. While comparisons to convalescent plasma are informative, it is still unknown what types and magnitude of immune responses are required for protection against SARS-CoV-2 infection or disease. Continued monitoring of participants will be necessary and is ongoing to understand the safety and durability of the immune response beyond 2 weeks post-vaccination. This trial only included participants less than 55 years of age. As older populations are at higher risk, the results from safety and immunogenicity studies in populations 55 and older will be required and are on-going. Additionally, this is part of a larger Phase 1 trial including a total of four different vaccine candidates, but results from only one candidate trial are reported here.

Value added

This study provides encouraging preliminary evidence that the COVID-19 RNA vaccine candidate (BNT162b1) is well tolerated and elicits an immune response at least comparable to antibody levels observed in a panel of convalescent plasma.

This review was posted on: 10 July 2020