A vaccine was (and still is to some degree), in fact, unpredictable. When will one be developed? How effective will it be? Will it have any negative side eff

A vaccine was (and still is to some degree), in fact, unpredictable. When will one be developed? How effective will it be? Will it have any negative side effects? How hard will it be to manufacture and distribute? All of these are important questions that were hard to predict. Today's announcement sheds some light on possible answers to these questions, so this new information is being priced into the market.