The Cambridge, Massachusetts-based company said the vaccine candidate, mRNA-1273, appeared to produce an immune response in eight people who received it similar to that seen in people convalescing from the virus.
"These interim Phase 1 data, while early, demonstrate that vaccination with mRNA-1273 elicits an immune response of the magnitude caused by natural infection," Moderna's chief medical officer Tal Zaks said.
"These data substantiate our belief that mRNA-1273 has the potential to prevent COVID-19 disease and advance our ability to select a dose for pivotal trials," Dr Zaks said.
Wall Street stocks jumped in early trading on the news, with the Dow Jones Industrial Average gaining around 775 points, or 3.3 percent.
"It's incredible what they can do and I've seen results. And the results are staggeringly good. So I'm very happy and the market's up very big," President Donald Trump told reporters.
Moderna, which was founded nine years ago, said the vaccine "was generally safe and well tolerated" and that patients suffered no more than redness or soreness from the shots.
In a conference call, Moderna chief executive Stephane Bancel said the preliminary tests inspired confidence that mRNA-1273 has "a high probability to provide protection" against the virus.
"We could not be happier about these interim data," Mr Bancel said of the Phase 1 test, the first of three in the development of a vaccine.
A man receives a shot during the clinical trial (AAP) Source: AP
Separate tests performed on mice showed that the vaccine prevented the virus from replicating in their lungs, according to the company.
The US government has invested nearly half a billion dollars in the development of Moderna's vaccine candidate.
It is being developed in a partnership with the National Institute of Allergy and Infectious Disease headed by Dr Anthony Fauci and the clinical test was carried out by the National Institutes of Health.
Three groups of 15 patients aged 18 to 55 received three different doses of the vaccine in the Phase 1 test, the complete results of which are not yet known.
The Phase 2 trial, with 600 subjects, has already received the green light from the US Food and Drug Administration and Moderna said they should begin this quarter.
A Phase 3 trial, the largest and most important to validate the efficacy of a vaccine, should begin in July.
People in Australia must stay at least 1.5 metres away from others. Check your state’s restrictions on gathering limits.
Testing for coronavirus is now widely available across Australia. If you are experiencing cold or flu symptoms, arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.
The federal government's coronavirus tracing app COVIDSafe is available for download from your phone's app store.
SBS is committed to informing Australia’s diverse communities about the latest COVID-19 developments. News and information is available in 63 languages at
