Moderna on Wednesday said it has begun submitting data to the Food and Drug Administration (FDA) about a booster dose of its COVID-19 vaccine.

The data submitted is for the use of a booster dose of its authorized two-shot vaccine at the 50 microgram dose, the company said.

The company said neutralizing antibodies had waned “significantly” prior to boosting approximately six months after the second dose.

The Biden administration announced last month that boosters would be available the week of Sept. 20 to most people fully vaccinated eight months earlier.

Context: The announcement comes after the U.S. authorized third doses of both Moderna and Pfizer’s COVID-19 vaccines for immunocompromised people last month, but boosters for the general public are not yet authorized.

More than 1 million people have since received a third dose according to the Centers for Disease Control and Prevention, though the agency does not distinguish if the people were immunocompromised.

What’s next: Shortly after the announcement from Moderna, FDA scheduled a key meeting of its outside advisory committee on vaccines. The group will meet Sept. 17 to discuss data from the Pfizer-BioNTech booster application — just three days before the Biden administration’s self-declared start date. It’s not clear if the scientists will follow the administration’s plan, though their recommendations are non-binding.