Moderna, Pfizer Covid Trial Placebo Recipients Want Vaccine (2)

Two extremely promising Covid-19 vaccines open the door to inoculating those who received placebos during the trials even as scientists will still need volunteers to test the long-term effects of the shots.

Moderna Inc. announced Monday its experimental Covid-19 vaccine demonstrated 94.5% effectiveness in preliminary results of its late-stage clinical trials. Those findings come a week after Pfizer Inc. announced the vaccine it is developing with BioNTech SE was also effective more than 90% of the time.

The extraordinary effectiveness rates in these interim findings prompted discussions between the National Institutes of Health and pharmaceutical companies about the best approach ...