Covid Vaccine: How long will it take for the F.D.A. to approve a vaccine?

Once the results are available, the Food and Drug Administration will review the data and either issue an emergency authorization — most likely for specific, high-risk groups of people like health care workers — or a broader approval for commercial licensure. Either way, the agency has said that it will consult with an advisory board of experts before making a decision.

Companies have been in contact with F.D.A. officials all along the way, and many experts predict that the agency will be able to approve an emergency authorization within days, if the results are clear enough.
When will a vaccine be available to any American who wants it?

The best-guess range from scientists, investors and federal health officials is the first half of next year.
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.

Even if one of the front-runners gets an answer about its vaccine this year, too few vaccines will have been produced to distribute them widely to the public. The head of Operation Warp Speed, Dr. Moncef Slaoui, told NPR that he estimated about 20 to 30 million doses of a vaccine would be ready by the end of the year, far short of the 100 million doses that Mr. Trump said Wednesday. (The front-runner vaccines all require two doses, given several weeks apart, further complicating the process.)

Dr. Slaoui also recently said that Americans would most likely not be widely vaccinated until the middle of 2021, and that the chance of having a vaccine by October or November was “extremely unlikely.”

The first few months of a vaccine’s availability will limit access to high-risk groups like older people or health care workers and police officers.

Peter Lurie, president of the Center for Science in the Public Interest and a former F.D.A. official, said he thought it was not unreasonable to expect that the first batches for high priority groups could be ready by February — “if everything lines up. And the lesson of drug development is that everything hardly ever all lines up.”

Earlier this month, the C.D.C. told public health agencies that two million doses of a vaccine might be available by the end of October, with 10 to 20 million doses possibly available by November, and 20 to 30 million by the end of December.

In a briefing for reporters Wednesday, officials with Operation Warp Speed described the first few months of a vaccine’s availability as a “constrained” phase when it would be available only to high-priority groups.

Those groups alone include millions of people. At a recent meeting of the Advisory Committee on Immunization Practices of the C.D.C., an agency official presented a slide showing that in the United States, there are as many as 20 million health care workers, up to 80 million essential workers and about 53 million people older than 65. Each of those people would need two doses of the vaccine for it to be effective.

For everyone else, the timing depends on the speed of manufacturing and distribution, and a willingness by the public to actually get vaccinated.

In the best-case scenario, additional vaccines could become available to the public early next year. Johnson & Johnson has said it expected to begin late-stage trials of its vaccine this month, and another company, Novavax, could begin its trial soon.

Stéphane Bancel, the chief executive of Moderna, said in an interview Wednesday that he expected a global shortage of vaccines well into next year. “In the first half of next year, at least maybe until Labor Day next year, I anticipate that the world is going to be massively supply-constrained, meaning not enough vaccine to vaccinate everybody,” Mr. Bancel said.

And that’s assuming that everyone wants to take a vaccine. Recent polls have shown that is not necessarily the case, especially if the vaccine is seen to have been rushed to market for political reasons.

Carl Zimmer contributed reporting.
Me: Mid to late 2021 is the earliest a vaccine “might” be available in any quantity and meantime Covid continues to evolve and more people die.