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.

At the very least, more testing will likely be needed on subjects who receive the half-dose first.

Porges believes that this product will never be licensed in the US due to the design of the company’s trials, which don’t appear to match the FDA’s minimum criteria, and the occurrence of severe safety events that resulted in the extended clinical hold on enrollment in the US (remember when the US put the AZ-Oxford trial recruitment on hold for a month).

The findings, according to Porges, confound his original thesis that “all spike protein vaccines are created equal”, which is manifestly not the case now. This raises questions about other adenovirus-vector vaccines, including the Johnson & Johnson’s vaccine.

On the other hand, Porges said “we remain optimistic about the outlook for adjuvanted protein sub unit vaccines such as those in development at Novavax and GSK/SNY, and these engineered synthetic virus vaccines may have a role long term in boosting, but it appears that the occurrence of pre-existing or post-vaccination immunity to the vector has a significant dampening effect on the efficacy of the vaccines (and may confer risk as well) and for this reason we believe these products are likely to be regarded as relatively marginal suppliers in the COVID vaccine market of the future.”

AZ announced earlier that after two doses, its modified chimpanzee adenovirus COVID vaccine (known as ChAdOx1) had achieved an average 70% efficacy after 132 infection events in its ongoing pivotal trial.

Even CNBC’s Meg Tirrell acknowledged that the AZ results were “a little bit more mixed” than the Pfizer and Moderna vaccines, adding in a tweet that the data were “confusing”.

A few weeks ago, Porges offered some positive commentary about the Pfizer vaccine and the Moderna vaccine. Regarding the latter, he said, the successful mRNA vaccine could help burnish Moderna’s reputation and transform it into a major player in the biotech space.