AstraZeneca plc's AZN prospects at being the first mover in the competition to develop a coronavirus vaccine have dimmed, according to an analyst at SVB Leerink.

The AstraZeneca Analyst: Andrew Berens has an Outperform rating on AstraZeneca with a $65 price target.

The AstraZeneca Takeaways: The clinical trial hold on AstraZeneca's coronavirus vaccine candidate AZD1222, which remains in place other than in the U.K., and the relatively higher number of COVID-19 cases needed for an interim analysis suggest the British drugmaker may have ceded the lead, Berens said in a Monday note.

This means AstraZeneca's vaccine candidate may not be the first to receive emergency use authorization, the analyst said. 

The U.S. trial remains on hold after the company voluntarily stalled clinical trials across sites following a case of transverse myelitis, an adverse event, he said. 

An AstraZeneca clinical study protocol released over the weekend showed that an interim and primary efficacy endpoint estimate should be at least 50% and that the lower bound of the confidence interval should be greater than 30%, Berens said. 

The first interim analysis will occur after 75 COVID-19 cases are reported, and the criteria for success will be statistical significance with an observed vaccine efficacy point estimate of at least 50%, the analyst said. 

The primary analysis will then follow after a total of 150 cases, with the criteria for success for the primary analysis being statistical significance with an observed vaccine efficacy point estimate of at least 50%, according to SVB Leerink. 

AstraZeneca Price Action: AstraZeneca shares were down 2.32% at $55.16 at last check Monday.