A head-to-head comparison of all three COVID-19 vaccines found Moderna is holding up better than Pfizer and the Johnson & Johnson vaccine provides the weakest protection.
But the researchers stressed that all three vaccines are still providing strong protection against people getting so sick that they end up in the hospital.
Researchers studied more than 3,000 people hospitalized between March and August. And found the Moderna vaccine was 93% effective at keeping people out the hospital and that protection appears to be holding steady.
The Pfizer vaccine's protection fell from 91% effective to 77%. The Johnson and Johnson vaccine was 71% effective.
The researchers speculated the Moderna vaccine may be the best because it uses a strong dose and spaced out the two shots a week longer.
The FDA is weighing whether to approve a booster for the Pfizer vaccine.