The fight against Covid-19 received a major shot in the arm on Friday as the US Food and Drug Administration (FDA) granted emergency use authorisation (EUA) to a second vaccine against the deadly coronavirus disease.

Jointly developed by Moderna, a Massachusetts-based pharma company, and the National Institute of Allergy and Infectious Diseases (NIAID), the Covid-19 vaccine has been authorised for use on people aged 18 years and older, and has joined Pfizer-BioNTech’s vaccine, already being administered since Monday, on the frontlines of the battle against the virus.

Moderna’s vaccine is similar to the one created jointly by Pfizer and BioNTech in many ways. They were both developed using the same cutting-edge mRNA technology and need to be administered in two doses, primary and booster.

But they are also different: the Moderna vaccine is more convenient to store and transport; common refrigerators would serve the purpose instead of the super-coolers needed for the Pfizer-BioNTech vials. Also, the interval between the two doses is longer by a week.

“There is much we still do not know about Sars-CoV-2 and Covid-19,” said Dr. Anthony Fauci, the most respected voice in the US on the pandemic and the head of the NIAID. “However, we do know that this vaccine is safe and can prevent symptomatic Covid-19 and severe disease.”

Moderna expects to supply between 100 million and 125 million doses globally in the first quarter of 2021, with 85-100 million of those doses available in the US.

The US food and drug regulator granted EUA to Moderna’s Covid-19 vaccine a day after an advisory board of outside experts had cleared it overwhelmingly. Its distribution, however, will depend on one more clearance, from the US Centers of Disease Control and Prevention (CDC), which is expected to follow shortly.

The United States is witnessing a continuing spike in Covid-19 cases. More than 233,000 new infections were reported in the last 24 hours and 3,270 fatalities. Dr. Fauci and other experts have warned of a grim winter with far more cases likely. More than 17 million Covid-19 cases have been reported in the US so far with at least 313,246 deaths.