A sense of dread is growing in some of the very poorest countries in the world as virus cases surge and more contagious variants take hold amid a crippling shortage of vaccine. ... With intensive care units filling up in cities overwhelmed by the pandemic, severe disease can be a death sentence. Africa is especially vulnerable. Its 1.3 billion people account for 18% of the world’s population, but the continent has received only 2% of all vaccine doses administered globally.