The obvious candidate in the Pfizer and Moderna vaccines is the dose of mRNA. From “mRNA-lipid nanoparticle COVID-19 vaccines: Structure and stability” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8032477/ we determine that each Pfizer shot contains 30 micrograms of mRNA, each Moderna shot contains 100 micrograms. Then from VAERS jan 1, 2021-sept 13, 2021 we determine the number of reports of fatalities within 30 days for Pfizer dose 1 (379), Pfizer dose 2 (774), Moderna dose 1 (627), Moderna dose 2 (774). We then need to normalize by the number of people vaccinated for each vaccine (113m Pfizer, 75.74m Moderna). If we divide the fatalities reported in VAERS by the total number of doses of each vaccine we obtain a relative fatality rate that is comparable across vaccines.
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