Low Dose Regimens of BNT162b2 mRNA Vaccine Exceed SARS-Cov-2 Correlate of Protection Estimates for Symptomatic Infection, in those 19-55 Years of Age

BackgroundAn exact correlate of protection (CoP) is not yet known for symptomatic COVID-19. However, it is still possible to show a new vaccine regimen exceeds an unknown CoP, provided the regimen shows an equivalent or greater immunological response in all measured indicators relative to the immunological response elicited by a clinically proven vaccine regimen. The principle of comparing immunogenicity between regimens is what the FDA, EMA, and Access Consortium use to authorize modifications to the vaccines for VOC, without requiring clinical efficacy studies before implementation. It is logical to apply the same principle to modifying vaccine doses if the data is available to do so. A two dose 30ug regimen of BNT162b2 has strong clinical evidence of efficacy, as does a single dose 30 ug regimen. The immunological markers for these regimens have been profiled in detail in Phase 1 and 2 trial data. MethodsThe immunological profile (including binding antibodies, viral neutralization, cytokine profiles, and CD4 and 8 expansion) of the 2 dose 30ug BNT162b2 vaccine is examined, referred to as a highly conservative CoP estimate. The single dose 30 ug BNT162b2 immunological profile is also examined, a tenable CoP estimate. Data from the phase 1 and 2 trials are examined to see if alternate regimens meet or exceed the level of each immune marker measured, relative to the regimens listed above that have proven clinical efficacy. ResultsFor adults aged 19-55, a 2 dose 10ug BNT162b2 regimen elicits a comparable response to the standard 30 ug dose for each immune indicator, with viral neutralization nearly an order of magnitude greater than the tenable CoP estimate. Similarly, a single dose 10ug BNT 162b2 regimen or a two dose 1ug BNT 162b2 regimen equals or exceeds the immunogenicity of a single 30 ug dose. ConclusionIf it is reasonable for the FDA, EMA, and Access Consortium to approve vaccine modifications without a clinical trial based on immunogenicity data, three alternate low dose regimens were identified that meet the requirements of having comparable immunogenicity relative to a protocol that has proven clinical efficacy. Immediate implementation of these lower dose regimens should be considered as they have major implications in alleviating vaccine supply, as well as improving vaccine side effect profile, and lowering total cost of vaccination.