University of California, Santa Cruz

Pfizer and BionTech are producing two vaccine candidates being studied in adults ranging from 18-55 and 65-85 in a placebo-controlled, observer-blinded dose-escalation study with 2 doses over 21-day intervals.
- BNT162b1: encodes a secreted trimerized SARS-CoV-2 receptor-binding domain
- BNT162b2: encodes perfusion stabilized membrane-anchored SARS-CoV-2 spike

The process is to select a single vaccine candidate and dose level for use.

BNT162b1/BNT162b2 from Pfrizer and BionTech

- Safety and immunogenicity of varying dose levels of BNT162b1 and Bnt162b2. The process was followed by testing the vaccine's safety through the proportion of participants exhibiting adverse events, 
- Immunogenicity assessment through a serum neutralization assay before the 7 and 21-day mark after Dose 1, and 21 days and 35 days after dose 2. 


Methods for testing BNT162b2

Discussion for BNT162b2

• Advance B2 at 30ug into Phase 2/3 with 18-85YO

• Milder systemic reactogenicity profile of B2, primarily 65-85

• Comparable immune response elicited 

• Lower reactogenicity (B2) may be due to the smaller size of the RNA constructs

• Note that immunogenicity decreased with age, yet still exceeded the base-line (GMT) of the convalescent serum panel

• Higer reactogenicity (B1) may be associated with an innate immune shut down of the host 

• B2 (full length spike) present greater diversity. 

• Limitations include: immunogenicity or safety beyond 7 days post dose-2 not available; uncertain importance of humoral and cellular immunity in protection from COVID-19; degree of protection against COVID also unknown. 

• Plan to address limitation with a bigger sample size, and diverse backgrounds

Discussions and Takeaways

The Phase 1/2 evaluation of BNT162b1 and BNT162b2 reports results in four domains: participant disposition and demographics, reactogenicity, adverse events and laboratory-value shifts, and immunogenicity.

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