People who received the one-dose Johnson & Johnson Covid-19 vaccine may need a booster shot to fend off some of the worrisome coronavirus variants now spreading worldwide, a study suggests.

U.S. President Joe Biden said the Centers for Disease Control is likely to advise that kids who have not been vaccinated against Covid-19 should wear masks when they return from summer holidays to school in the fall.

Kids in the United States will likely be able to get Covid-19 vaccinations by the end of 2021 or the first quarter of 2022, Dr. Anthony Fauci, the nation’s top infectious disease expert, said at an event on May 19.