The vaccine, developed with a new technology known as messenger RNA (mRNA), would be a powerful tool to fight a pandemic that has infected over 55 million people worldwide and killed 1.3 million.
The following is a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for Covid-19, the illness caused by the virus.
Moderna sees success in pivotal vaccine trial
Moderna Inc's experimental vaccine was 94.5 percent effective in preventing Covid-19 based on interim data from a late-stage trial, the company said on Monday.
That followed last week's news that Pfizer Inc's vaccine was also more than 90 percent effective based on initial data.
Pending more safety data and regulatory review, the United States could have two vaccines authorized for emergency use in December.
Both vaccines employ synthetic messenger RNA (mRNA), which coaxes cells to make certain virus proteins that the immune system sees as a threat and mounts a response against.
Moderna's trial involved 30,000 racially diverse US adults, including people at high risk for severe Covid-19.
Only five of the 95 cases in the initial analysis occurred in participants who received the vaccine, while the rest had received a placebo.
The vaccine, administered in two shots 28 days apart, also appeared to prevent cases of severe Covid-19.
Side effects, largely occurring after the second shot, included muscle aches, fever, headache and redness at the injection site.
Moderna's vaccine does not need ultra-cold storage like Pfizer's, making it easier to distribute.
Mutated virus 'more vulnerable' to new vaccines
The mutated form of the new coronavirus that is now the most common strain worldwide is more infectious but may also be more vulnerable to vaccines under development, new research suggests.
In experiments reported on Thursday in Science magazine, researchers saw that the newer strain, which originated in Europe, is more efficient at infecting airway cells and at making copies of itself, although it does not appear to produce more severe illness.
The D614G mutation causes a "flap" to open on the tip of a spike on the surface of the virus, improving its ability to break into cells, but also creating a pathway for antibodies in vaccines to enter the virus and disable it, the researchers explained in a statement.
New SARS-CoV-2 mutations are continually emerging, "like the recently discovered mink SARS-CoV-2 cluster 5 variant in Denmark that also encodes D614G," coauthor Ralph Baric of the University of North Carolina School of Medicine said in the statement.
"We must continue to track and understand the consequences of these new mutations on disease severity, transmission, host range and vulnerability to vaccine-induced immunity," he added.
Paper forms pose coronavirus risk for lab staff
When laboratory personnel are processing Covid-19 tests, there is a small risk that the paper forms accompanying the specimens can be contaminated with the new coronavirus, a new report cautions.
Researchers at the Birmingham Public Health Laboratory in the UK analysed randomly selected paper forms and specimen packaging during a period when the team was processing about 700 Covid-19 tests daily.
Of the 37 items they tested, one piece of paperwork carried genetic material from the coronavirus.
The form had come from a low-risk hospital ward, and the specimen from the patient was negative for the virus, "indicating contamination may be occurring as a result of environmental or healthcare worker contamination," the researchers wrote on Thursday in the Journal of Hospital Infection.
They call for "stringent laboratory practices" — hand hygiene, appropriate personal protective equipment — and "use of electronic test requesting where possible."