- Both Moderna and Pfizer have provided data to the FDA showing that their shots are safe and effective at preventing COVID-19 infections.
- But, the shots do have some subtle differences.
- Moderna’s might better protect against severe cases, while Pfizer’s seems to have milder side effects.
- Here’s everything you need to know.
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With US regulators releasing their most detailed look yet at Moderna’s coronavirus vaccine, it’s becoming increasingly likely that the US will soon have not just one, but two working, authorized COVID-19 shots.
The Food and Drug Administration granted emergency use authorization for Pfizer’s two-shot vaccine last week, and agency regulators are expected to greenlight Moderna’s very similar two-dose mRNA shot course later this week. An FDA expert panel will meet Thursday to discuss and vote on Moderna’s shot, teeing up an agency decision that could come as soon as Friday.
Late-stage clinical trials for both vaccines are ongoing, meaning more results could still come in, and change what we’ve learned about how well these shots work.
But so far, the two vaccines appear quite similar, and they both seem to be safe and highly effective, based on trials that have been conducted on tens of thousands of people around the world. The trials compare people who got two doses of the Pfizer-BioNTech vaccine or of Moderna’s vaccine to people who got fake shots known as placebos.
Here’s what we know so far.
Both shots are overwhelmingly effective at preventing symptomatic cases of COVID-19
The primary goal of both vaccine studies was to see if the shots can prevent the symptomatic kind of COVID-19, where people exhibit outward symptoms of illness, such as coughing, fevers, and shortness of breath. Both vaccines did well at that task.
Pfizer: Pfizer’s vaccine was 95% effective at preventing symptomatic disease, with the trial recording 162 COVID-19 cases in the placebo group and 8 in people who got the real vaccine. Pfizer’s study began counting cases sooner than Moderna’s, with researchers starting to count cases one week after people got the second (booster) dose.
Moderna: Moderna’s shot was 94.1% effective at preventing symptomatic disease. The study tallied 196 COVID-19 cases among volunteers, with 185 in the placebo group and just 11 among those getting the experimental vaccine. This study started counting cases 14 days after people got their second shot.
The vaccines work really well at preventing the most severe COVID-19 infections, and deaths
People with severe cases of COVID-19 can end up hospitalized, paralyzed, or dead. Fortunately, both Pfizer and Moderna’s shots seem to protect people very well from some of the most severe instances of disease, and no one who was vaccinated died from COVID-19 during these studies.
Pfizer: 8 fully vaccinated people (out of more than 18,100) in Pfizer’s study got sick with COVID-19. One of those infections was severe, but none required hospitalization. Three placebo recipients also became severely ill, according to the study’s final analysis. Two of those people were hospitalized, with one requiring intensive…