That’s a big deal, folks.According to Centers for Disease Control and Prevention (CDC) data, vaccinating half of the adult Americans has marked significant progress since the vaccines were first authorized in December."This is a major milestone in our country's vaccination efforts," White House senior COVID-19 adviser Andy Slavitt said at a press briefing on Tuesday (local time), nothing that 1% of adults were fully vaccinated when the Biden administration came into office, reported The Hill.It further reported that the achievement symbolizes a step closer to President Biden's next goal of getting 70 per cent of adults to have at least one vaccine dose by the fourth of July.