Massachusetts company’s virus vaccine shows promising early results.

Moderna, the Massachusetts biotechnology company behind a leading effort to create a coronavirus vaccine, announced promising early results from its first human safety tests Monday.

The eagerly awaited data provide a preliminary look at one of the eight vaccines worldwide that have begun human testing. The data have not been published in a scientific journal and are only a first step toward showing the experimental vaccine is safe and effective.

The company’s stock soared on the report that eight participants who received low and medium doses of Moderna’s vaccine had blood levels of virus-fighting antibodies that were similar or greater than those in patients who recovered. That would suggest, but doesn’t prove, that it triggers some level of immunity.

Moderna’s announcement comes days after one of its directors, Moncef Slaoui, stepped down from the board to become chief scientist for Operation Warp Speed, a White House initiative to speed up vaccine development. Watchdogs called out Slaoui’s apparent conflict of interest. Filings with the Securities and Exchange Commission show Slaoui’s stock options in Moderna are worth more than $10 million with the company’s share price at $66.69. In regular trading Monday, Moderna’s stock soared about 25% to more than $83.

Slaoui will divest his Moderna stock holdings, effective this morning, according to a spokeswoman for the Department of Health and Human Services. He will donate the value the Moderna stock gained since Thursday, before the announcement of his position leading Operation Warp Speed, to cancer research.

Moderna also received $483 million from the Biomedical Advanced Research and Development Authority, a federal agency. Moderna has also partnered with a contract development and manufacturing firm, Lonza, and Slaoui stepped down from that company’s board on Monday.

“Slaoui’s blatant financial conflicts of interest disqualify him for the role of vaccine czar, unless he commits immediately to global vaccine access conditions over the obvious profit interests of the corporations he serves,” said Peter Maybarduk, director of the Access to Medicines Program at Public Citizen, a consumer advocacy group.

Sen. Elizabeth Warren, D-Mass., called for Slaoui to divest his stock options, tweeting it is “a huge conflict of interest for the White House’s new vaccine czar to own $10 million of stock in a company receiving government funding to develop a COVID-19 vaccine.”