AstraZeneca's announcement that its adenovirus-vector vaccine is roughly 70% effective (which followed an announcement claiming the vaccine is safe and effective in the elderly) failed to impress investors, as Astrazeneca shares tumbled on the news in premarket.

But AZ shares took a second leg lower on Monday when a health-care analyst dropped some damning commentary that has caught the market's attention.

SVB Leerink analyst George Porges said Monday that the company is likely to be roundly criticized for publishing its results without enough data on safety and other factors. The vaccine's (known formally as ChAdOx1) safety disclosure simply stated that "no serious safety events related to the vaccine have been confirmed", as well as for its results, which the company "tried to embellish" by highlighting a reported 90% efficacy in the relatively small sub-set of subjects in the study who received the modified initial vaccination followed by the "full dose" four weeks later.