Several companies in the race for a coronavirus vaccine have stumbled upon a new and unexpected hurdle: activists protesting the use of a substance that comes from sharks in their products. The oily compound, called squalene, is churned out by shark livers and has immunity-boosting powers, which has led several companies to use it as an ingredient in vaccines. A group called Shark Allies has mounted a campaign calling on the Food and Drug Administration and other regulatory bodies to halt the sourcing of the compound from sharks, warning that mass distribution of a coronavirus vaccine could require harvesting tissue...