What you need to know about the Pfizer, Moderna and AstraZeneca vaccines

Three leading coronavirus vaccine candidates have dazzled the world with strong evidence they can prevent illness. The vaccines are made by different companies: One was developed by the giant pharmaceutical Pfizer and its German partner BioNTech and was given emergency use authorization to the nation’s first coronavirus vaccine; another by the biotechnology firm Moderna, in partnership with the National Institute of Allergy and Infectious Diseases, is seeking regulatory clearance in the U.S. and the third is from the University of Oxford and its partner AstraZeneca.

What will happen next?

Companies report results from late-stage clinical trials.

NOV. 9

Pfizer and BioNTech

More than 90 percent effective

NOV. 16

Moderna

95 percent effective

NOV. 23

AstraZeneca

Vaccine efficacy ranged from 62 to 90 percent

Companies seek emergency authorization to provide the vaccines more broadly.

FDA regulators will review the effectiveness, safety and manufacturing of each vaccine.

An FDA advisory committee will vote on whether to recommend that the agency greenlight each vaccine.

Mid- to late December:

The FDA may authorize one or more vaccines.

One or two days later:

A Centers for Disease Control and Prevention advisory committee will discuss prioritizing vaccines for high-risk groups.

End of 2020:

The government projects that Pfizer and Moderna will provide 40 million doses, enough for 20 million people, by the end of the year.

Companies report results from late-stage clinical trials.

NOV. 9

Pfizer and BioNTech

More than 90 percent effective

NOV. 16

Moderna

95 percent effective

NOV. 23

AstraZeneca

AstraZeneca

Vaccine efficacy ranged from 62 to 90 percent

Companies seek emergency authorization to provide the vaccines more broadly.

FDA regulators will review the effectiveness, safety and manufacturing of each vaccine.

An FDA advisory committee will vote on whether to recommend that the agency greenlight each vaccine.

The FDA may authorize one or more vaccines.

One or two days later:

A Centers for Disease Control and Prevention advisory committee will discuss prioritizing vaccines for high-risk groups.

End of 2020:

The government projects that Pfizer and Moderna will provide 40 million doses, enough for 20 million people, by the end of the year.

Companies report results from late-stage clinical trials.

NOV. 16

Moderna

95 percent effective

NOV. 23

AstraZeneca

Vaccine efficacy ranged from 62 to 90 percent

NOV. 9

Pfizer and BioNTech

Over 90 percent effective

Companies seek emergency authorization to provide the vaccines more broadly.

FDA regulators review the effectiveness, safety and manufacturing of each vaccine.

An FDA advisory committee will vote on whether to recommend that the agency greenlight each vaccine.

The FDA may authorize one or more vaccines.

One or two days later:

A Centers for Disease Control and Prevention advisory committee will discuss prioritizing vaccines for high-risk groups.

End of 2020:

The government projects that Pfizer and Moderna will provide 40 million doses, enough for 20 million people, by the end of the year.

Why is the FDA using emergency powers to approve a vaccine?

The FDA has emergency authority to issue temporary approvals of medical products to get them to the public more quickly during public health emergencies. Such authorizations require less data and can be done more rapidly than full approvals. Since February, the FDA has used this power to authorize hundreds of coronavirus tests and a few treatments. But it has authorized a vaccine that way only once in its history — in 2005, against anthrax — and that was under sharply different circumstances.

Some experts have expressed qualms about using that process for a coronavirus vaccine that would be given to hundreds of millions of people, but those criticisms have become muted as the pandemic has raged, killing thousands of Americans a week.

Peter Marks, director of the FDA center that oversees vaccines, has vowed to insist on an emergency standard for a vaccine that is roughly equivalent to what’s needed for a full licensure. Even so, the available safety data — two months follow-up on half the trials’ participants after their second shots — is shorter than in traditional trials. And some questions, such as the duration of protection, can’t be answered now — that data will be collected as the trials continue.

When will I be able to get vaccinated?

That depends on your job, your age and your health. For the most up-to-date information see The Post’s vaccine distribution tracker.

The vaccines could begin to be distributed as soon as mid-December to those in high-risk groups — an estimated 200 million people — who will receive priority, according to a framework devised by an advisory committee to the Centers for Disease Control and Prevention. Government officials said that if both the Pfizer and Moderna vaccines are authorized, they anticipate having enough doses for 20 million people by year’s end.

The exact criteria for who will be first in line will be defined immediately after a vaccine is authorized, but the general principles have been discussed for months. You may qualify for earlier access because of your job: Health-care workers and first responders are likely to be among those prioritized. People who have essential jobs, such as teachers and food workers; those who are at higher risk because of their age; and those who have underlying conditions that increase their risk for severe disease are also likely to receive earlier access.

Healthy younger adults who don’t have medical conditions or high-risk jobs are likely to begin to get vaccinated starting in April, but not everyone will be able to get the shots immediately. And children aren’t even included in most coronavirus vaccine trials — Pfizer is the first company to expand its trial to people 12 and older — so they probably will be among the last to get access.

“I would say starting in April, May, June, July — as we get into the late spring and early summer — that people in the so-called general population, who do not have underlying conditions or other designations that would make them priority, could get” shots, said Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases.

How will the vaccines be shipped?

The vaccine from Pfizer and BioNTech must be kept at an ultracold, minus-70 degrees Celsius, a requirement that will add a wrinkle to an unprecedented vaccination campaign. The company has created its own GPS-tracked coolers filled with dry ice to distribute it.

How Pfizer will ship its vaccine at ultra-low temperatures

The frozen vaccine is packaged into 2-milliliter glass vials — each holding five doses.

One tray holds 195 vials. Up to five trays fit into a box.

The vaccine cartons are surrounded by 50 pounds of dry-ice pellets.

A GPS temperature monitor is placed in each shipment. The vaccine must be kept below minus- 70 degrees Celsius.

How Pfizer will ship its vaccine at ultra-low temperatures

The frozen vaccine is packaged into 2-milliliter glass vials — each holding five doses.

One tray holds 195 vials.

Up to five trays fit into a box.

The vaccine cartons are surrounded by 50 pounds of dry-ice pellets.

A GPS temperature monitor is placed in each shipment. The vaccine must be kept below minus-70 degrees Celsius.

How Pfizer will

ship its vaccine

at ultra-low temperatures

The frozen vaccine is packaged into 2-milliliter glass vials — each holding five doses.

One tray holds 195 vials. Up to five trays fit into a box.

The vaccine cartons are surrounded by 50 pounds of dry-ice pellets.

A GPS temperature monitor is placed in each shipment. The vaccine must be kept below minus-70 degrees Celsius.

How Pfizer will ship

its vaccine at ultra-

low temperatures

The frozen vaccine is packaged into 2-milliliter glass vials — each holding five doses.

One tray holds 195 vials. Up to five trays fit into a box.

The vaccine cartons are surrounded by 50 pounds of dry-ice pellets.

A GPS temperature monitor is placed in each shipment. The vaccine must be kept below minus-70 degrees Celsius.

Each vial of the Pfizer vaccine holds five doses when diluted. Once thawed, the undiluted vial can be kept in a refrigerator for only five days. A diluted vial can be kept for only six hours before it must be discarded.

The Moderna vaccine is stored frozen at minus-20 degrees Celsius, but it keeps for a month at refrigerator temperatures. This could make it easier to distribute to pharmacies and rural areas that don’t have specialized freezers.

The AstraZeneca-Oxford vaccine can be stored at refrigeration temperatures for up to 6 months, which will make it far easier to distribute and administer in much of the world.

How many doses will I need?

Both the Moderna and Pfizer vaccines require two doses. Pfizer’s booster shot will be given three weeks after the first one; Moderna’s is spaced four weeks later.

The AstraZeneca-Oxford vaccine also requires two doses, but the trial found that it was far more effective when the first dose was half the typical dose, with the second given a month later. It remains to be seen which dose the company will submit to regulators for clearance.

How do the vaccines work?

The Pfizer vaccine is the first vaccine using messenger RNA technology ever approved for human use by the Food and Drug Administration. It is different from more traditional vaccines, which often use a weakened or dead version of a virus, or a laboratory-generated protein. Both vaccines use a snippet of the virus’s genetic code to instruct cells to build the spike protein on the surface of the coronavirus, teaching the immune system to recognize the real thing.

RNA vaccines contain a strip of genetic material within a lipid bubble.

Inside the cell, ribosomes read the mRNA instructions

for the spike protein.

The cell then begins to generate copies of the spike protein.

Antigen-presenting cells (APCs) consume the viral proteins and pass viral peptides to T-helper cells.

The immune system, presented with the peptide, learns to recognize the virus and releases cytotoxic

T cells and B cells.

Cytotoxic T cells detect and eliminate virus-infected cells.

Antibodies from B-cells block the virus from infecting healthy cells.

RNA vaccines contain a strip of genetic material within a lipid bubble.

Inside the cell, ribosomes read the mRNA instructions

for the spike protein.

The cell then begins to generate copies of the spike protein.

Antigen-presenting cells (APCs) consume the viral proteins and pass viral peptides to T-helper cells.

The immune system, presented with the peptide, learns to recognize the virus and releases cytotoxic

T cells and B cells.

Cytotoxic T cells detect and eliminate virus-infected cells.

Antibodies from B-cells block the virus from infecting healthy cells.

RNA vaccines contain a strip of genetic material within a lipid bubble.

Inside the cell, ribosomes read the mRNA instructions for the spike protein.

The cell then begins to generate copies of the spike protein.

Antigen-presenting cells (APCs) consume the viral proteins and pass viral peptides to T-helper cells.

The immune system, presented with the peptide, learns to recognize the virus and releases cytotoxic T cells and B cells.

Cytotoxic T cells detect and eliminate virus-infected cells.

Antibodies from B-cells block the virus from infecting healthy cells.

RNA vaccines contain a strip of genetic material within a lipid bubble.

Inside the cell, ribosomes read the mRNA instructions for the spike protein.

The cell then begins to generate copies of the spike protein.

Antigen-presenting cells (APCs) consume the viral proteins and pass viral peptides to T-helper cells.

The immune system, presented with the peptide, learns to recognize the virus and releases cytotoxic T cells and B cells.

Cytotoxic T cells detect and eliminate virus-infected cells.

Antibodies from B-cells block the virus from infecting healthy cells.

The AstraZeneca-Oxford vaccine uses a harmless cold-causing virus that typically infects chimpanzees to deliver to the body’s cells the genetic code for the spike protein. The cells then make a replica of the spike protein and the immune system learns to recognize the real virus.

How were the vaccines made so fast?

Historically, vaccines have taken years to develop. Before these, the mumps vaccine — which took four years to develop — was the fastest to be approved for use in humans. Developing messenger RNA vaccines like the Pfizer and Moderna candidates has been fast because scientists were able to start their work before there was a known case of the novel coronavirus in this country, using the viral genome shared online as a template. Making messenger RNA vaccines does not require time-consuming steps, such as growing ingredients in chicken eggs.

Are the vaccines safe?

The full safety data haven’t been made available yet, but no serious safety concerns have been reported in either trial. Intensive safety monitoring will continue after the vaccines begin to be used. The side-effects profile of the Pfizer vaccine includes pain at the injection site, as well as fatigue, chills and fever. The side effects noted in Moderna’s news release include pain at the injection site, muscle aches and headaches.

Should I still get vaccinated if I already had the coronavirus?

We are still learning how long immunity to the coronavirus lasts, after an infection or a vaccination. Typically, an infection causes better immunity than a vaccine, but not always — the vaccines for tetanus and human papillomavirus, for example, offer better protection than recovering from a natural infection.

The coronavirus vaccine trials did not exclude people who already had been infected, and the full data from those trials may help reveal how the vaccine performed in those people. Until the CDC committee evaluates the full data on any authorized vaccine, the agency won’t make recommendations about whether people who already were infected should receive it.

How much will the vaccines cost?

The federal government has pre-purchased hundreds of millions of vaccine doses with taxpayer money, and vowed to make them available free.

Will I still need to socially distance?

Yes. Even after a vaccine is approved, experts say people will need to wear masks and socially distance — in part because the vaccine doses will be limited, and it will take time to immunize enough of the population to stop the virus from spreading. Experts say the return to normalcy could take many months or longer.

Will I have a choice on which vaccine to take assuming more than one is approved?

Supply will be far short of demand initially, so you are unlikely to be offered options in the near term. Also, the vaccines have different storage and handling requirements making it likely that each administration site will only have one vaccine on hand, at least to start with.

But Kelly Moore of the Immunization Action Coalition believes that once there are plenty of products available, that may change. Moore hopes supply may meet demand by the second half of next year, opening the potential for people to have options, particularly if one vaccine is preferable for certain age groups, for example.

How will I know which vaccine might be best for me?

Experts say they need more data about the vaccines before being able to answer that question, but here’s how the process works: The FDA will authorize each vaccine based on safety and efficacy results. A CDC advisory committee will subsequently make recommendations to health-care providers for how the vaccines may be used, including whether one vaccine may be preferable for certain demographic groups.Claire Hannan, executive director of the Association of Immunization Managers offered the reminder that, as with any other vaccine, it’s best to discuss those recommendations with your health-care provider.

What will happen if I don’t get vaccinated?

Two other vaccines are in the final phase of testing in the United States, and those trials are also moving much faster than expected because of surging coronavirus cases. Two more are expected to begin soon. Later-generation vaccines are also still in development.

The goal is to immunize enough people to achieve herd immunity, when enough people are immune that a disease can no longer spread. The number of people who need to be immunized to reach that milestone will depend on how effective the vaccines are — a factor that won’t be clear until the trials have finished.

Could I be mandated to get the vaccine by my employer?

That’s not likely anytime soon. Vaccines authorized under the FDA’s emergency authority, as these will be at the start, cannot be mandated, said Beth Bell, a member of the federal advisory panel on immunizations that will recommend to the CDC who should get the first doses. There also won’t be enough vaccine for everyone for months. Many employers offer flu vaccines to their employees, but such programs are voluntary in most settings except hospitals.

Eventually, the vaccines probably will be approved under the FDA’s more lengthy licensure rules and will no longer be considered experimental. But even then, requiring a coronavirus vaccine as a condition for returning to the factory floor or office or retail showroom would create the potential for conflicts, said Jennifer B. Rubin, a labor lawyer at the law firm Mintz in San Diego.

“It’s going to create some really interesting political and legal issues about the haves and have-nots,” she said. “What about people working at fast-food restaurants, servers, people who staff gyms? There’s going to be a need for guidance under the circumstances for employers.”

Frances Stead Sellers, Lena H. Sun and Christopher Rowland contributed to this report.

This story was first published November 17.

Leave a Reply

Your email address will not be published. Required fields are marked *