Pfizer and BioNTech have announced that their COVID-19 vaccine is effective against the Delta variant after two doses and that a third dose will boost the protection even more.

The companies are also working on a new version of the vaccine that they hope will provide stronger protection against the Delta variant, which recently became the leading variant in the U.S. They plan to submit data to the FDA for Emergency Use Authorization later this year.

Pfizer and BioNTech said they hope to start clinical trials of the new version of the vaccine, which “targets the full spike protein of the Delta variant,” in August, and that the first batch of the messenger RNA needed for the trial has already been manufactured at BioNTech’s facility in Mainz, Germany.