US biotech firm Moderna on Monday announced its experimental vaccine against Covid-19 was almost 95 percent effective, marking a major breakthrough in the quest to end the pandemic.
Moderna released early results from a clinical trial with more than 30,000 participants, after American pharmaceutical company Pfizer and its German partner BioNTech last week said their vaccine was 90 percent effective.
The news came as virus infections surged across Europe and the United States.
Both vaccines are based on new technology that uses synthetic versions of molecules called "messenger RNA" to hack into human cells, and effectively turn them into vaccine-making factories.
"This positive interim analysis from our Phase 3 study has given us the first clinical validation that our vaccine can prevent COVID-19 disease, including severe disease," said Moderna CEO Stephane Bancel.
"Today's news of a second vaccine is further reason to feel hopeful," tweeted President-elect Joe Biden, but he cautioned that its widespread distribution was months away.
"Until then, Americans need to continue to practice social-distancing and mask-wearing to get the virus under control," he said.
Moderna plans to submit applications for emergency approval around the world within weeks, and says it expects to have approximately 20 million doses ready to ship in the US by the end of the year.
The company, which has received $2 billion from the US government under "Operation Warp Speed," added it is on track to manufacture between 500 million to a billion doses globally in 2021.
Global infections from Covid-19 have soared past 54 million with more than 1.3 million deaths since the virus emerged in China late last year.
China and Russia also say that they have manufactured effective Covid-19 vaccines.
China is developing several vaccines, of which five are undergoing large-scale global trials
Questions remain
The promising results of both vaccines are seen as a validation for mRNA technology, which has never before been brought to regulatory approval.
It works by providing human cells with the genetic instructions to make a surface protein of the coronavirus, which trains the immune system to recognize the real virus.
Making a traditional vaccine is a longer process that normally involves developing a weakened form of a pathogen.
It is not yet clear how long lasting the protection will be from either the Moderna or Pfizer vaccines, nor how well they work for the elderly, the age-group at highest risk from Covid-19.
Another open question is whether they stop people who are exposed to the virus from transmitting it on to the other people, even though they may be themselves protected from the disease.
