Moderna is set to ask the FDA to authorize its coronavirus vaccine, a key step before it can be given to more people

Moderna is set to ask US regulators to allow the emergency use of its experimental coronavirus vaccine, starting a process that could allow the shot to be given more widely within weeks.

The biotech company plans to file today for emergency use authorization with the US Food and Drug Administration, Moderna said in a statement, about a week after Pfizer and BioNTech asked the FDA to green light their vaccine. The company is also seeking approval from regulators in other countries.

Moderna said its vaccine was 94.1% effective at preventing COVID-19, the disease caused by the new coronavirus, in an analysis of 196 COVID-19 cases from a 30,000-person trial. The company said on November 16 that the vaccine was 94.5% effective, in an earlier analysis from that trial.

"We believe that our vaccine will provide a new and powerful tool that may change the course of this pandemic and help prevent severe disease, hospitalizations and death," Moderna CEO Stéphane Bancel said in the statement.

Vaccines developed by Moderna and by Pfizer are likely to be the first immunizations that can help the US stop the COVID-19 pandemic. Pfizer has said its shot was 95% effective at preventing COVID-19. The US surpassed record positive case counts and hospitalizations in November. More than a quarter of a million Americans have died from COVID-19 so far.

AstraZeneca and Oxford shared preliminary data on their coronavirus vaccine last week, saying it's 70% effective on average. Outside experts have raised questions about some of the data, and US authorization of the vaccine likely won't happen until a trial of the vaccine finishes in that country.

Read more: Coronavirus-vaccine frontrunner Moderna is planning to start testing its shot in kids — a crucial step to halting the pandemic

Moderna CEO Bancel previously told Business Insider it was too soon to compare the Pfizer and Moderna vaccines, but said they are both "excellent vaccines that are going to help a lot of Americans and help a lot of people around the world."

He said he anticipates every American having access to vaccines by late May 2021. In the meantime, he said wearing masks and social distancing are the "best weapon" to stop COVID-19 from spreading.

"Even if no other vaccines were going to make it, as a worst-case scenario, I think by Memorial Day, end of June, any Americans who want a vaccine will have their hands on a vaccine," Bancel told Business Insider's Andrew Dunn.

Independent experts will carefully review trial data to determine whether the vaccine is ready for the public.

The company said side effects from the vaccine were typically mild or moderate. Some volunteers developed severe side effects from Moderna's vaccine, but they were not life-threatening. Common severe side effects included fatigue, injection site pain, and headaches.

Moderna also said the vaccine was highly effective at preventing severe cases of COVID-19. The company said there were 30 cases of severe disease in the trial, all in people who got the placebo.

Getting a vaccine may not prevent people from spreading the virus to others. Volunteers were not tested for coronavirus unless they developed symptoms, meaning asymptomatic trial participants could still have gotten the disease and infected others.

Read more: Moderna salaries revealed: From $60,000 to $250,000, here's how much you could make at the biotech firm that recently announced a successful COVID-19 vaccine

Now that Moderna has filed for emergency use authorization, the FDA will conduct a rigorous review of the trial data to ensure the vaccine is safe for the public.

Peter Marks, an FDA director leading the vaccine vetting process, said career scientists and independent experts will analyze the data in a publicly broadcasted meeting, which is scheduled for December 17.

That group, known as an advisory committee, will then vote on whether or not to recommend that FDA authorize the vaccine. The FDA could decide whether to allow emergency use of the vaccine shortly after that.

Marks said said he hopes letting the public see the authorization process unfold will build trust in the approved vaccine

The US needs to address challenges transporting and properly administering the vaccine once it becomes available.

Once the FDA authorizes a vaccine, the US intends to move quickly with getting vulnerable people access to the shot.

The US has already bought 100 million doses of Moderna's vaccine, and has the option of buying 400 million additional ones. 

Health and Human Services Secretary Alex Azar said he expects to start giving vaccines to the most vulnerable populations, like healthcare workers, by the end of the year. Azar said he expects the general to have access to a vaccine by April.

But ensuring the vaccines get properly transported and administered isn't easy.

The process to transport Moderna's vaccine has some advantages over Pfizer. Moderna's shots can be stored in a fridge for up to a month, while Pfizer's vaccine only lasts 5 days in a vaccine fridge. Pfizer's shot additionally needs to be shipped out on dry ice in special GPS-tracked briefcases.    

Moderna and Pfizer's vaccines require two shots given weeks apart, and some experts say getting 100% of vaccine recipients to return for a follow-up could be difficult. Vaccinating a vast majority of Americans is crucial to achieving herd immunity protection. Anthony Fauci recently said roughly 80% of the population must get vaccinated before the country returns to "some degree of normalcy."

"What I would like to see is the overwhelming majority of people get vaccinated so we can, essentially, really crush this outbreak," Fauci said in an interview with the New York Times. "This is going to be a difficult task."