The levels of “neutralising antibodies” were similar to the levels found in patients who had recovered after contracting the virus in the community.
The Massachussetts-based company is now enrolling two more cohorts with participants who are aged 55 to 70 and 71 and older to test the vaccine.
The vaccine would have to pass through several more rounds of studies in order to be proven safe and effective for the general public.
Health experts expressed cautious optimism but warned it is common for vaccines to stumble in later trail stages.
“These are significant findings but it is a Phase 1 clinical trial that only included eight people,” Amesh Adalja, an infectious disease expert at Johns Hopkins University, told Reuters. “It was designed for safety, not for efficacy.”
Moderna stocks jumped by almost 20 per cent after the results were released.
Less promisingly, early results for an experimental Oxford University vaccine found it did not stop the virus in monkeys and may only be partially effective.
“All of the vaccinated monkeys treated with the Oxford vaccine became infected when challenged as judged by recovery of virus genomic RNA from nasal secretions,” William Haseltine, a former Harvard Medical School professor who helped develop early HIV/Aids treatments, wrote in Forbes.
“There was no difference in the amount of viral RNA detected from this site in the vaccinated monkeys as compared to the un-vaccinated animals. Which is to say, all vaccinated animals were infected.”
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 Tuesday morning American Eastern Standard Time, 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.
Democrat Senator Elizabeth Warren 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”.
with Washington Post
Matthew Knott is North America correspondent for The Sydney Morning Herald and The Age.