Moderna says their COVID-19 vaccine remains 93 percent effective through six months, but a third dose will be needed before winter.

Thursday, the company said the vaccinated will need the booster shot, which is currently being tested, in part as a response to the rise in breakthrough infections from the Delta variant.

The Moderna announcement this week comes after pharmaceutical giant Pfizer said their own COVID-19 remained effective for months after the second dose.

Moderna also said Thursday that they are working on a single shot that would provide an annual booster against COVID-19, as well as the flu and the respiratory condition RSV.