Don't Expect Covid-19 Research to Deliver Certainty
What we know about the disease is still fraught with error and contradictions, but that shouldn’t prevent us from acting.
Looking for answers about Covid-19
Photographer: Arnold Jerocki/Getty Images
To assess the safety and effectiveness of their Covid-19 vaccines, BioNTech SE, Pfizer Inc. and Moderna Inc. sponsored clinical trials overseen by independent boards that recruited tens of thousands of participants, randomly assigned them to receive vaccines or placebos and waited to see if there was a discernible difference in outcomes between the two groups.
With the rapid spread of the new coronavirus in the U.S. this fall, they didn’t have to wait long — and the results were stunning. In both trials, about 95% of those who developed Covid symptoms were in the placebo group, meaning that the vaccines appeared to be 95% effective.