Johnson & Johnson, the maker of a single-shot COVID-19 vaccine, reported Wednesday that a second dose drastically increased the antibody response to the delta variant, a finding that could sway federal authorities to sign off on booster shots.

“With these new data, we also see that a booster dose of the Johnson & Johnson COVID-19 vaccine further increases antibody responses among study participants who had previously received our vaccine,” said Mathai Mammen, the global head of Janssen research and development at Johnson & Johnson.