MONEYWEB app instead? May further complicate efforts to vaccinate the world. By John Lauerman, Bloomberg 13 Apr 2021 13:41 Image: Bloomberg US health officials called for an immediate pause in use of Johnson & Johnsonâs single-dose Covid-19 vaccine after six women who received it developed a rare and severe form of blood clotting. The decision comes at a crucial juncture in the US vaccination effort, which has been gaining speed in recent weeks at the same time that a worsening outbreak driven by coronavirus variants is gripping the upper Midwest. And it is likely to heighten wor...