Your questions about coronavirus vaccines, answered

By Carolyn Y. JohnsonAaron SteckelbergLena H. Sun and Laurie McGinleyDec. 21, 2020HomeShare69

The first coronavirus vaccine was administered to U.S. health-care workers Dec. 14. Now that a second vaccine is being used, public health officials are hoping that at least 70 percent of the population will be inoculated so that the nation can achieve herd immunity and stop the virus’s spread. Here are answers to some frequent questions.

What you need to know about the vaccines

How do the Pfizer-BioNTech and Moderna vaccines work?

The first vaccine authorized in the United States was developed by pharmaceutical giant Pfizer and the German firm BioNTech. It consists of two shots, given three weeks apart. Moderna’s vaccine, developed by a Massachusetts biotechnology company in partnership with the National Institute of Allergy and Infectious Diseases, was the second vaccine cleared. It consists of two shots, given 28 days apart.

The Pfizer-BioNTech and Moderna shots are the first vaccines using messenger RNA technology approved for human use by the Food and Drug Administration. The approach is different from that of more traditional vaccines, which often use a weakened or dead version of a virus, or a laboratory-generated protein. It uses a synthesized scrap of genetic information that is wrapped in a protective fat layer to keep it from disintegrating. When it goes into cells in the muscle of the upper arm, it contains molecular instructions that tell your cells to create a protein that triggers an immune response to the spike protein on the surface of the coronavirus. This means your immune system will be prepared to eliminate the pathogen if it tries to invade.

Are they safe?

Both vaccines passed rigorous safety reviews by the FDA.

The agency authorized the Pfizer-BioNTech vaccine for people age 16 and over after reviewing data from 44,000 participants in a randomized clinical trial. A 53-page analysis by the agency found that some people who received injections had unpleasant but tolerable side effects, including fatigue, headaches, muscle pain, joint pain, chills and fever. Reviewers said the two months of follow-up on 38,000 of those participants provide evidence of “a favorable safety profile, with no specific safety concerns identified that would preclude issuance of an [emergency authorization].”

The FDA cleared the Moderna vaccine for people age 18 and over, based on data from a clinical trial with 30,000 participants. The agency found side effects were similar to those with the Pfizer-BioNTech shot.

Some experts have expressed qualms about using emergency use authorizations for coronavirus vaccines 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 use an emergency standard roughly equivalent to what’s needed for a full licensure. Even so, the available safety data — two months of 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.

Will the vaccine protect me from getting the coronavirus?

The two-shot Pfizer-BioNTech vaccine has been shown to be 95 percent effective in randomized trials. The FDA’s independent review found that of more than 20,000 people who received both vaccine doses, only eight contracted the coronavirus, and just one person fell seriously ill. By contrast, 162 people in the placebo group contracted the coronavirus, and nine of those people developed serious illness. There was even some evidence that the first shot of the vaccine protected against illness, but the FDA said there was insufficient data to draw firm conclusions.

Pfizer enrolled approximately 44,000 people in its late-stage clinical study in the United States, Germany, Turkey, South Africa, Brazil and Argentina. Researchers divided the participants into two groups:

One group received two doses of the vaccine. Another group was given two doses of a placebo. To eliminate any unintentional bias toward the results, neither group knew whether they received the vaccine or the placebo. Participants were exposed to the coronavirus as they went about their normal routines. 8 sick with covid-19 from the vaccine group, 1 severely ill. 162 sick with covid-19 from the placebo group, 9 severely ill. Moderna’s vaccine was found to be 94 percent effective at preventing disease in the trial, and particularly effective against severe disease.

Scientists don’t yet know how long the protection from the vaccines last. And they don’t know whether the shots prevent people from becoming infected without knowing it and inadvertently spreading the 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 such as the Pfizer-BioNTech 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.

Should I still get vaccinated if …

I already had the coronavirus?

The Centers for Disease Control and Prevention says vaccination should be offered to people regardless of whether they had a prior infection. 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.

I have covid-19 now?

It’s best to wait to be inoculated until you’ve recovered from your illness and have met all the criteria to end self-isolation to avoid spreading the infection to others. There is no recommended minimum interval to get vaccinated after you’ve recovered.

I’m pregnant, plan to get pregnant soon or I’m breastfeeding?

Pregnant or breastfeeding people who are part of a group recommended to get the shots — for instance, health-care workers — might want to consider talking with their medical providers beforehand. Pregnant people have been excluded from coronavirus vaccine trials, so there is no data on the safety of the vaccines for them, or its effects on the breastfed infant.

The American College of Obstetricians and Gynecologists says a conversation with a clinician may be helpful but should not be required. Pregnant people who get infected with the coronavirus are at greater risk of death and severe illness than those who are not pregnant, even as the overall risk remains small.

The Pfizer-BioNTech and Moderna vaccines do not contain live virus, or any enhancers to boost an immune response, and are not thought to be a risk to the breastfeeding infant. They do not alter human DNA in the people who get it and cannot cause any genetic changes. Also, this type of vaccine breaks down quickly and doesn’t enter the nucleus of the cell.

Pfizer said it is planning to report to the FDA by the end of the year on a developmental and reproductive toxicity study in animals that could help clarify any risks.

I have allergies?

People who have mild allergies to food, pets, environment or latex can get the Pfizer-BioNTech and Moderna vaccines.

Concerns about rare but severe allergic reactions were sparked by recent reports that two health-care workers in Britain had such reactions after being vaccinated. The CDC said Dec. 19 that it was reviewing six cases of anaphylaxis in people given the Pfizer-BioNTech vaccine.

Government officials and medical experts say these rare reactions should not deter the general public from taking the vaccine, although the standard guidance is that people who get the shot should linger at the clinic or doctor’s office for 15 minutes, and 30 minutes if they have a history of severe allergic reactions. Anaphylaxis can be quickly reversed with epinephrine and other medicines.

The FDA and the CDC say people with a history of severe allergic reactions to any component of the vaccines should not get the shots.

Researchers do not know which component in the Pfizer-BioNTech vaccine might have triggered the severe allergic responses. Many, but not all, of the chemicals in that shot and the Moderna one are the same. They both use polyethylene glycol, a chemical widely used in medicines, cosmetics and other household products, which the FDA has said it is looking at as a possible culprit. Officials at the National Institutes of Health are devising a study to find out why a small number of people have had severe allergic reactions to the Pfizer-BioNTech vaccine.

If you have a history of severe allergic reaction to another vaccine or injectable therapy, that should not necessarily preclude you from getting the shots. But the CDC advises that you consult your doctor beforehand.

What about people with HIV infections or who have other immunocompromising conditions, or who take immunosuppressive medications?

The vaccines haven’t been studied in immunocompromised people, but those individuals are not anticipated to be at increased risk of adverse reactions. However, they should talk to their providers beforehand because their immune systems may not respond optimally.

I want to get the vaccine …

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 Washington Post’s vaccine distribution tracker.

A CDC advisory committee has said the first group to receive the vaccines should be health-care workers and residents of long-term care facilities. States, however, have the final say. Government officials have said they anticipate having enough doses of the two vaccines to inoculate 20 million people with their first shots by year’s end.

The next priority group for the vaccines should be essential workers — grocery store employees, teachers, emergency workers and others who are on the front lines of the nation’s labor force — and adults 75 years old and older, the CDC advisory panel said. Those groups could get shots beginning early next year.

A third group that should get priority includes other essential workers, adults 65 to 74 and people 16 to 64 with high-risk medical conditions, the committee advised.

Who exactly is an “essential worker” already is setting off debate around the country. Complicating the situation: There will not be enough vaccine to meet demand any time soon.

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.

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.

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 vaccines are deployed, 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 have only one vaccine on hand, at least to start with.

But Kelly Moore of the Immunization Action Coalition believes that once plenty of products are 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.

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