The U.S. plans to buy 100 million additional doses of Johnson & Johnson’s Covid-19 vaccine, two administration sources told NBC News. President Joe Biden will announce the plans Wednesday during a White House meeting with executives from J&J and Merck. J&J currently has a deal with the U.S. government to provide 100 million doses by the end of June. The federal government shipped out nearly 3.9 million doses of the single-shot vaccine last week and says it plans to distribute 16 million more by the end of this month. The announcement comes as the administration works to ramp up the production of J&J’s vaccine after it ... (full story)