Findings of a recent study, Comparison of two highly-effective mRNA vaccines for COVID-19 during periods of Alpha and Delta variant prevalence, show that Moderna’s COVID-19 vaccine appears to have a higher effectiveness rate compared with the Pfizer vaccine. This observational study was conducted from a Minnesota patient cohort in July 2021. Both vaccines appeared to be highly protective (Moderna 86%, Pfizer 76%) from January to July 2021, which was the period of time when the Delta variant first became predominant. However, the researchers observed the rates of protection for both vaccines dropped during the month of July 2021, and that the Moderna vaccine maintained higher protection than Pfizer (Moderna 76%, Pfizer 42%).
Investigators of this observational study conclude that further evaluation of the mechanisms of the two vaccines are warranted to understand the difference in protectiveness.
Read the Medpage news article here
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Read the full text MedRxiv observational study article here
Note: This article is a preprint and has not been peer-reviewed [what does this mean?]. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.