On Nov. 24, 2021, Johnson & Johnson announced the U.S. Food and Drug Administration (FDA) had issued Emergency Use Authorization (EUA) for a booster dose of the Johnson & Johnson COVID-19 vaccine for adults aged 18 and older at least two months following primary vaccination with single-shot Johnson & Johnson COVID-19 vaccine; and for eligible individuals who received a different authorized or approved COVID-19 vaccine. The Johnson & Johnson booster shot was the same formulation and dosage as the primary shot.

This decision was based on scientific evidence, including initial data from the Phase 3 ENSEMBLE study that demonstrated the vaccine was 85 percent effective in preventing severe disease, and showed protection against COVID-19 related hospitalization and death, beginning 28 days after vaccination