Johnson & Johnson announced that its one-dose vaccine provided strong protection against Covid-19. It was less effective against a new variant. |
| The Johnson & Johnson results came with a significant cautionary note: The vaccine’s efficacy rate dropped from 72 percent in the United States to 57 percent in South Africa, where a highly contagious variant is driving most cases. Studies suggest that this variant also blunts the effectiveness of Covid-19 vaccines made by Pfizer-BioNTech, Moderna and Novavax. |
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