The drugmaker Moderna announced highly encouraging results on Monday, saying that complete data from a large study show its coronavirus vaccine to be 94.1 percent effective, a finding that confirms earlier estimates.
The company said that it applied on Monday to the Food and Drug Administration to authorize the vaccine for emergency use, and that if approved, injections for Americans could begin as early as Dec. 21.
The hopeful news arrives at a particularly grim moment in the U.S. health crisis. Coronavirus cases have surged and overwhelmed hospitals in some regions, and health officials have warned that the numbers may grow even worse in the coming weeks because of travel and gatherings for Thanksgiving.
The new data from Moderna show that its study of 30,000 people has met the scientific criteria needed to determine whether the vaccine works. The findings from the full set of data match an analysis of interim data released on Nov. 16 that found the vaccine to be 94.5 percent effective.
The study also showed that the vaccine was 100 percent effective at preventing severe disease from the coronavirus. The product was developed in collaboration with government researchers from the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases.
Stéphane Bancel, the chief executive of Moderna, said in an interview that the company was “on track” to produce 20 million doses by the end of December, and from 500 million to a billion in 2021. Each person requires two doses, administered a month apart, so 20 million doses will be enough for 10 million people.
Moderna is the second vaccine maker to apply for emergency use authorization; Pfizer submitted its application on Nov. 20. Pfizer has said it can produce up to 50 million doses this year, with about half going to the United States. Its vaccine also requires two doses per person.
“Be thinking people in nursing homes, the most vulnerable, be thinking health care workers who are on the front lines,” Alex M. Azar II, the secretary for health and human services, said on the CBS program “This Morning” on Monday.
He said the C.D.C. advisers would base their recommendations on the latest data on virus cases across the country. Asked about the role of states in the distribution process, he said that doses would be shipped out through normal vaccine distribution systems, and governors would be “like air traffic controllers,” determining which hospitals or pharmacies receive shipments.
Although governors will determine which groups are prioritized, he said he hoped that they will follow the federal recommendations. He added that he would speak to governors on Monday afternoon with Vice President Mike Pence. In response to a question about how officials could guard against people using money or connections to jump the proverbial line, Mr. Azar vowed to “call out any inequities or injustices that we see.”
The White House moved quickly to take credit for the progress on vaccines. “President Trump’s Operation Warp Speed is rapidly advancing on a trajectory of success to save millions of American lives — five times faster than any other vaccine in history,” Michael Bars, a spokesman for Mr. Trump, said in a statement.
Over all, about 13.3 million Americans have contracted the virus, and more than 265,900 have died. In November alone, there were more than four million new cases and 25,500 deaths in the United States. Worldwide, there have been nearly 62 million cases and almost 1.5 million deaths.
One of those is made by AstraZeneca, which announced positive but puzzling preliminary results on Nov. 23: Its vaccine was 90 percent effective in people who received a half dose and then a full one, but 62 percent effective in those who received two full doses. Researchers are waiting for more data.
Moderna’s application for emergency use authorization included data from its Phase 3 study of 30,000 people. The application, several hundred pages long, also included several thousand pages of additional data.
F.D.A. scientists will examine the information, and the application is likely to undergo a final review on Dec. 17 by a panel of expert advisers to the agency, Mr. Bancel said, adding that he expected the advisers to make a decision within 24 to 72 hours. The F.D.A. usually follows the recommendations of its advisory panels.
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Officials at Operation Warp Speed, the government’s program to accelerate vaccine development, have said vaccinations could begin within 24 hours after the F.D.A. grants authorization.
Mr. Bancel said that Moderna had not yet begun shipping vaccines across the country, and that it would not do so until the emergency authorization was granted.
The Road to a Coronavirus Vaccine
Words to Know About Vaccines
Confused by the all technical terms used to describe how vaccines work and are investigated? Let us help:
Adverse event: A health problem that crops up in volunteers in a clinical trial of a vaccine or a drug. An adverse event isn’t always caused by the treatment tested in the trial.
Antibody: A protein produced by the immune system that can attach to a pathogen such as the coronavirus and stop it from infecting cells.
Approval, licensure and emergency use authorization: Drugs, vaccines and medical devices cannot be sold in the United States without gaining approval from the Food and Drug Administration, also known as licensure. After a company submits the results of clinical trials to the F.D.A. for consideration, the agency decides whether the product is safe and effective, a process that generally takes many months. If the country is facing an emergency — like a pandemic — a company may apply instead for an emergency use authorization, which can be granted considerably faster.
Background rate: How often a health problem, known as an adverse event, arises in the general population. To determine if a vaccine or a drug is safe, researchers compare the rate of adverse events in a trial to the background rate.
Efficacy: A measurement of how effective a treatment was in a clinical trial. To test a coronavirus vaccine, for instance, researchers compare how many people in the vaccinated and placebo groups get Covid-19. The real-world effectiveness of a vaccine may turn out to be different from its efficacy in a trial.
Phase 1, 2, and 3 trials: Clinical trials typically take place in three stages. Phase 1 trials usually involve a few dozen people and are designed to observe whether a vaccine or drug is safe. Phase 2 trials, involving hundreds of people, allow researchers to try out different doses and gather more measurements about the vaccine’s effects on the immune system. Phase 3 trials, involving thousands or tens of thousands of volunteers, determine the safety and efficacy of the vaccine or drug by waiting to see how many people are protected from the disease it’s designed to fight.
Placebo: A substance that has no therapeutic effect, often used in a clinical trial. To see if a vaccine can prevent Covid-19, for example, researchers may inject the vaccine into half of their volunteers, while the other half get a placebo of salt water. They can then compare how many people in each group get infected.
Post-market surveillance: The monitoring that takes place after a vaccine or drug has been approved and is regularly prescribed by doctors. This surveillance typically confirms that the treatment is safe. On rare occasions, it detects side effects in certain groups of people that were missed during clinical trials.
Preclinical research: Studies that take place before the start of a clinical trial, typically involving experiments where a treatment is tested on cells or in animals.
Viral vector vaccines: A type of vaccine that uses a harmless virus to chauffeur immune-system-stimulating ingredients into the human body. Viral vectors are used in several experimental Covid-19 vaccines, including those developed by AstraZeneca and Johnson & Johnson. Both of these companies are using a common cold virus called an adenovirus as their vector. The adenovirus carries coronavirus genes.
Trial protocol: A series of procedures to be carried out during a clinical trial.
The government has arranged to buy vaccines from both Moderna and Pfizer and to provide it to the public free of charge. Moderna has received a commitment of $955 million from the U.S. government’s Biomedical Advanced Research and Development Authority for research and development of its vaccine, and the United States has committed up to $1.525 billion to buy 100 million doses.
Shares of Moderna’s stock surged on Monday from the news, by 20 percent, to nearly $153 a share.
Both Moderna’s and Pfizer’s vaccines use a synthetic form of genetic material from the coronavirus called messenger RNA, or mRNA, to program a person’s cells to make many copies of a part of the virus. That viral fragment sets off alarms in the immune system and trains it to recognize and attack the real virus if it tries to invade.
No mRNA vaccine has reached the market before, and the candidates from Pfizer and Moderna have faced considerable skepticism from scientists and a wary public.
But the strong results from both vaccines have begun to quash the doubts.
So far, neither vaccine has had serious side effects, but many recipients have had headaches, mild fevers, fatigue, joint and muscle aches, and sore arms for a day or two.
Of the 30,000 people in the Moderna study, half were vaccinated and half received placebo shots of salt water; neither the participants nor their doctors knew who got what. Then, researchers monitored the participants to see who contracted the coronavirus and watched for side effects.
To determine statistically whether the vaccine was effective, a total of 151 cases of Covid-19 were needed.
Because the coronavirus has been surging in the United States, Moderna wound up with 196 cases — 185 in the placebo group, and 11 in the vaccinated group, meaning that the vaccine was 94.1 percent effective at preventing Covid-19.
The 196 people who got sick with Covid-19 reflected the diversity of Moderna’s volunteers: Thirty-three were 65 or older. The group also included 29 Hispanic volunteers, six Black participants, four Asian Americans and three multiracial people. The efficacy and safety appeared the same in all of the subgroups and by gender, Moderna said in its announcement.
Thirty participants had severe cases, all in the placebo group. One died.
Mr. Bancel said he considered the statistics about prevention of severe disease the most important data from the study.
“This is why I think this vaccine is going to be a game-changer,” he said. The vaccine will reduce hospitalizations and deaths, he added, “and I hope get this country back to its pre-pandemic state.”
Moderna said it was also seeking authorization to market its vaccine in Europe, Canada, Britain, Israel and Singapore.