The drug maker Pfizer said on Friday that it had submitted an application to the Food and Drug Administration to authorize its coronavirus vaccine for emergency use, setting in motion an accelerated regulatory process that could allow the first Americans to get a vaccine by the middle of December.
Pfizer and its German partner, BioNTech, announced Wednesday that the vaccine was safe and 95 percent effective, and that it also worked well in older people and in preventing severe Covid-19.
Another front-runner, Moderna, said on Monday that its vaccine, which uses similar technology, was 94.5 percent effective and that the company also expected to apply soon for emergency authorization.
The two vaccines use a synthetic version of coronavirus genetic material, called mRNA, to program a person’s cells to churn out many copies of a fragment of the virus.
An emergency authorization would allow limited groups of Americans to get the vaccines before the F.D.A. has completed the typical monthslong approval process, but agency officials have made clear through new guidelines that their bar for emergency authorization will be high.
In a video message Friday, Pfizer’s chief executive, Dr. Albert Bourla, called it a “historic day,” and said: “It is with great pride and joy — and even a little relief — that I can say that our request for emergency use authorization for our Covid-19 vaccine is now in the F.D.A.’s hands.”
Both of the companies’ vaccine candidates began large human trials on the same day, July 27, leading the pack of six vaccines the federal government has invested in through its crash vaccine development program, Operation Warp Speed.
If the two vaccines are authorized for emergency use, federal and company officials have said there could be enough doses to immunize about 20 million Americans before the end of the year, a group that would most likely include health care workers and nursing home residents. There are an estimated 17 million to 20 million health care workers in the United States, and about a million people living in nursing homes.
After lowering expectations for how many millions of vaccines they can produce this year, the companies expect to ramp up their manufacturing early next year. Like with other kinds of vaccines, mass producing them for the coronavirus has proved to be a complex and delicate process requiring sterile conditions and precise control of temperature and humidity. The mRNA technology has also never been commercially manufactured. If other vaccines are also authorized, hundreds of millions of doses could be available by the spring, according to federal officials.
Both Pfizer and Moderna have arranged deals with the government so that the vaccines will be free to Americans and distributed according to plans worked out between the federal government and the states. CVS and Walgreens also have federal deals to begin immunizing nursing home residents. On Tuesday, Alex M. Azar II, the secretary of the Department of Health and Human Services, said that 99 percent of the country’s nursing homes had signed up to be part of the program.
Regulators at the F.D.A. plan to take about three weeks to review Pfizer’s vaccine before an outside panel of experts meets to review the application the second week of December. That meeting has been scheduled for Dec. 10.
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 agency typically, though not always, follows the advice of its advisory committees. If committee members reach a consensus about the effectiveness of Pfizer’s vaccine, the company could receive emergency clearance by mid-December.
Because Moderna is also on the verge of submitting its vaccine for review, the outside panel could review the company’s vaccine soon after Pfizer’s.
Pfizer said on Friday that the company has begun regulatory submissions in Australia, Canada, Europe, Japan and Britain, and that it plans to apply in other countries “in the immediate future.”
Inside the F.D.A., Pfizer’s application will be reviewed by the agency’s Center for Biologics Evaluation and Research, which has organized large teams of medical and compliance officers, epidemiologists and statisticians to dig into thousands of pages of data about the safety and effectiveness for each vaccine, as well as information on how companies plan to safely and consistently manufacture large batches of the product.
The process could take longer if the reviewers come across errors, or if they need to ask for additional data. Regulators expect the manufacturing data to spur intense deliberation, as companies have scrambled to turn over that information in time.