WASHINGTON — According to published reports, the Food and Drug Administration will soon allow Americans to receive a booster shot of COVID-19 vaccine different from their original dose.

The federal drug regulator is expected to announce the so-called “mix and match” strategy on Wednesday when it officially authorizes boosters of the two-dose Moderna and single-shot Johnson & Johnson vaccines.

The U.S. Centers for Disease Control and Prevention has already approved booster doses of the two-dose Pfizer vaccine for certain people starting at six months after their last shot, among them people 65 years old and older, nursing home residents, frontline workers such as teachers and health care workers, and people between the ages of 50 and 64 with underlying conditions.

The decision to authorize boosters of the Moderna and Johnson & Johnson vaccines comes on the heels of a study released last week by the U.S. National Institutes of Health that revealed people who received the Johnson & Johnson vaccine had a more than 76-fold rise in their antibody levels after receiving a Moderna booster, compared with a 35-fold rise in their antibody levels after receiving a Pfizer booster shot. People who received a second Johnson & Johnson shot saw only a fourfold rise in their antibody levels.