Pfizer/BioNTech COVID-19 vaccine effectiveness drops after 6 months -study

The analysis showed that the vaccine's effectiveness in preventing hospitalization and death remained high at 90% for at least six months, even against the highly contagious Delta variant of the coronavirus. The data suggests that the drop is due to waning efficacy, rather than more contagious variants, researchers said.

The effectiveness of the Pfizer Inc/BioNTech SE vaccine in preventing infection by the coronavirus dropped to 47% from 88% six months after the second dose, according to data published on Monday that U.S. health agencies considered when deciding on the need for booster shots.

The data, which was published in the Lancet published medical journal, had been previously released in August ahead of peer review.