Two doses of Pfizer and Moderna's Covid-19 vaccine are necessary, officials say, but questions still linger
Two doses of Pfizer and Moderna's Covid-19 vaccine are necessary, officials say, but questions still linger
US needs to hold on for another 2 or 3 months without easing up on Covid-19 measures, expert says. Here's what's at stake
'A big, big deal.' Experts say the green light for Johnson & Johnson's vaccine helps bring US a step closer to normalcy
