Updated 19/12/2020: This article has been updated to include the latest information

The Moderna coronavirus vaccine has been approved by the US Food and Drug Administration (FDA) for emergency use in the United States.This makes the Moderna jab the second Covid-19 vaccine to get approval for emergency use in the US after the FDA gave the green light to the Pfizer/BioNTech vaccine last week.

On Thursday, December 17, an independent advisory panel voted 20 to 0 with one abstention that the Moderna vaccine should be approved for emergency use for people aged 18 and over.

"We thank the committee for their review and for their positive recommendation in support of Emergency Use Authorization,” Stéphane Bancel, Chief Executive Officer of Moderna, said in a statement. “We look forward to getting our vaccine to people in the US to help address this ongoing public health emergency.”

Clinical trials of the Moderna vaccine have proved to be very positive. The phase 3 trial, involving 30,000 people, showed that the jab has an efficacy of around 94.5 percent and was 100 percent effective against severe Covid-19. Research published earlier this month also found that the vaccine produces potent antibodies that last for at least three months and it looks likely it will confer longer-term immunity too.

The vaccine was well tolerated with the main side-effect being localized pain at the injection site for 80 percent of the participants. A fifth of people did not experience any pain at all and 1 percent experienced severe pain. Other common reactions included fatigue and headaches. The majority of adverse reactions were classified as mild or moderate but only remained for an average of one to two days. 

Like Pfizer’s vaccine, the Moderna vaccine is an mRNA vaccine. This is a new type of vaccine that works by injecting a small synthetic fragment of the virus's genetic code, the mRNA, into the human body. This genetic code gives instructions to our cells to make a harmless piece of the virus’s spike protein. The body’s cells read these instructions and produce that harmless fragment. Once this piece of protein enters the bloodstream, our immune system learns to produce antibodies for it. 

The Moderna vaccine remains stable at standard refrigerated conditions of 2-8°C (36-46°F) and can be kept at room temperature conditions for up to 12 hours. On the other hand, the Pfizer vaccine requires ultra-cold storage, around -75°C (-103°F). This means it will potentially be easier to transport, store, and distribute the Moderna vaccine.

The approval of a second vaccine can't come soon enough. As of December 18, the US has endured over 17.2 million cases of Covid-19 and suffered over 310,000 deaths, according to the Johns Hopkins University Covid Dashboard. Worldwide, there have now been over 75 million cases and at least 1.66 million deaths. 

For more information about Covid-19, check out the IFLScience Covid-19 hub where you can follow the current state of the pandemic, the progress of vaccine development, and further insights into the disease.