Also read: Moderna asking US, European regulators to OK its virus shots

The meeting of the European Medicines Agency's human medicines committee (CHMP) comes amid high rates of infections in many EU countries and strong criticism of the slow pace of vaccinations across the region of some 450 million people.

The EMA has already approved a coronavirus vaccine made by American drugmaker Pfizer and Germany's BioNTech. Both vaccines require giving people two shots.

Ahead of the meeting on the Moderna vaccine, the agency said in a tweet that its experts were “working hard to clarify all outstanding issues with the company.” It did not elaborate on what those issues were. Moderna also declined to comment.

Early results of large, still unfinished studies show both the Moderna and the Pfizer-BioNTech vaccines appear safe and strongly protective, although Moderna’s is easier to handle since it doesn’t need to be stored at ultra-frozen temperatures.

Also read: Pfizer: COVID-19 shot 95% effective, seeking clearance soon

The United States, Canada and Israel have already approved use of the Moderna vaccine. The U.S. gave it the green light for emergency use in people over 18 years on Dec. 18, followed by Canada five days later with an interim authorization also for people over 18. Israel authorized the vaccine on Monday.

If the EU agency joins the list, its decision will have to be confirmed by the bloc's executive commission in Brussels before vaccinations with the Moderna shot can begin.

Also read: US clears Moderna vaccine for COVID-19, 2nd shot in arsenal

Moderna said Monday that it is increasing its estimate for global vaccine production in 2021 from 500 to 600 million doses. The company said it is “continuing to invest and add staff to build up to potentially 1 billion doses for 2021.”

Both Moderna’s and Pfizer-BioNTech’s shots are mRNA vaccines, made with a groundbreaking new technology. They don’t contain any coronavirus – meaning they cannot cause infection. Instead, they use a piece of genetic code that trains the immune system to recognize the spike protein on the surface of the virus, ready to attack if the real thing comes along.

Also read: UN health agency clears Pfizer and BioNTech vaccines

The EU officially began giving out Pfizer-BioNTech vaccination shots on Dec. 27, but the speed of each nation's inoculation program has varied widely. France vaccinated around 500 people in the first week, while Germany vaccinated 200,000. The Dutch were only beginning to give out vaccine shots Wednesday, the last EU nation to start doing so.

Also read: EU regulator gives conditional approval to BioNTech-Pfizer COVID vaccine