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COVID-19 vaccine FAQ: Answers to your most common questions

All U.S. adults eligible for COVID vaccine
All U.S. adults eligible for COVID vaccine 08:08

A year into the coronavirus pandemic, Americans are anxious, depressed and frustrated — but also hopeful, as vaccines are rolling out to millions of people across the country.

But as the vaccine has arrived, so have the questions: Who should and shouldn't get it? What's safe to do once you're vaccinated? Can the side effects be stopped? 

Here are the answers to your most frequently asked questions about the vaccine, including its effectiveness, its risks, and what to expect when it comes to side effects.

When will I get the COVID vaccine?

Vaccine distribution got off to a patchy and confusing start, with some states rolling out faster than others, but availability is steadily increasing and eligibility has expanded to include everyone in the U.S. age 16 and up. By mid-March, more than 100 million doses had been administered, with the pace picking up to over 3 million shots per day.

Frontline health care workers started off at the top of the list for shots, followed by older adults, essential workers, and people with certain health conditions, such as diabetes, that would make them more likely to get severely ill if they contracted COVID-19. States then started expanding access to larger groups of people as the supply increased.

As of April 19, all U.S. adults and teens age 16 and over are eligible for the shots. 

To find a location near you, the CDC points people to the website

When can children get the vaccine?

Estimates vary, but some ages may be able to get vaccinated against COVID-19 by the fall of 2021. "I think it's possible that this vaccine gets moved into the high school-age population in the fall," former FDA commissioner Dr. Scott Gottlieb said on CBS News' "Face the Nation" in February.

Vaccine makers have begun including children in clinical trials, with results expected in the coming months. "We anticipate data on high school age individuals, 12 to 17 years old, by the beginning of the fall," Dr. Anthony Fauci said at a briefing. "I would say more than likely, we will not have data on elementary school children until at least the first quarter of 2022."

Moderna begins vaccine trials in children und... 02:24

For now, Pfizer's vaccine is authorized by the FDA for recipients ages 16 and up. The Moderna and Johnson & Johnson vaccines are for ages 18 and up.

What are the differences between the COVID vaccines?

In December 2020, the FDA authorized emergency use of the first two coronavirus vaccines in the U.S., one made by Pfizer and BioNTech, and the other by Moderna. Both require two doses. A third vaccine, from Johnson & Johnson's Janssen Biotech division, got FDA authorization in late February and only requires one shot.

All three proved highly effective at preventing severe illness, hospitalizations and deaths from COVID-19.

The Pfizer and Moderna vaccines are both made using messenger RNA, or mRNA, technology.

Traditionally, vaccines have been made from a weakened or inactivated germ that trains the immune system to fight off infection if it encounters the virus in the future. But mRNA vaccines do something different: They teach human body cells how to make a harmless piece of a protein — a "spike protein" — that's also found on the surface of the coronavirus. After that protein piece emerges on the surface of a cell, the human immune system recognizes it and begins making antibodies for it — which offer protection if the person is exposed to the actual virus in the future.

One difference between the Pfizer and Moderna vaccines is the wait time between the two required doses: Pfizer's are given 21 days apart, while the Moderna shots are given 28 days apart. 

Johnson & Johnson took a different approach, developing what's called a viral vector vaccine — a type that has been used for years against other diseases. It uses an altered, harmless, non-replicating version of a common cold virus, called adenovirus type 26, to introduce genetic instructions for the "spike protein." The immune system responds by making antibodies which will protect the person if they're infected by SARS-CoV-2, the virus that causes COVID-19, in the future.

Johnson & Johnson's single-dose vaccine has the advantage of being stored in regular refrigerators, while the two others must be stored and transported at below-freezing temperatures. 

A two-dose vaccine from Oxford and AstraZeneca is approved in the U.K. and European Union but not yet in the U.S. Its clinical trial data is still being scrutinized by U.S. health officials. 

Why was use of the Johnson & Johnson vaccine "paused"?  

On April 13, U.S. health officials recommended a temporary "pause" in use of the Johnson & Johnson vaccine after several instances of rare blood clots were reported. The initial reports involved six women between the ages of 18 and 48 whose symptoms developed six to 13 days after vaccination. More than 6.8 million people have received doses of the Johnson & Johnson vaccine.

The CDC and FDA said the blood clots, called cerebral venous sinus thrombosis, were seen alongside low levels of blood platelets — an unusual combination that requires specialized treatment.

"Treatment of this specific type of blood clot is different from the treatment that might typically be administered. Usually, an anticoagulant drug called heparin is used to treat blood clots. In this setting, administration of heparin may be dangerous, and alternative treatments need to be given," the agencies said.

Dr. Fauci on COVID-19 vaccine hesitancy 05:40

The agencies said the "adverse events" seem to be extremely rare, but that the pause is important so that health care providers can be made aware of the reactions and properly recognize and manage the cases, given the unique treatment required.

Dr. Anthony Fauci said the pause is a sign that medical safeguards are working properly.

"One of the things you can take away from all of this is that when the surveillance system, the CDC and the FDA, say that something is safe, you can be sure that it's safe," Fauci said.

What are the known side effects of the COVID vaccines? 

In general, side effects are not uncommon with vaccines, and the COVID-19 shot is no exception. Your body's immune reaction could include the same kinds of side effects often seen with other vaccines, including a sore arm, fatigue, fever, chills or headaches.

"This is expected," Dr. Neeta Ogden, an internal medicine specialist and immunologist, said in an interview on CBSN.

"People should maybe think about vaccinating on weekends, for example," she said. "You probably might need to take a day off from work. … This is predictable and I don't think that it is alarming."

Not everyone experiences side effects, but doctors stress that their occurrence is normal and should not discourage people from getting the shots. 

Doctor on COVID variants and vaccines 09:14

Can the side effects be minimized?

The CDC offers some advice on ways to combat vaccine side effects: After vaccination, use or lightly exercise the arm that got the shot. Take Tylenol or Motrin for any pain you may have, but only after you've gotten the shot, not before. The CDC also recommends drinking plenty of liquids after you get either the first or second dose. If redness or tenderness increases at the vaccination site in the days following the shot, the CDC recommends that you call your doctor.

Do the COVID vaccines protect against new variants? 

Health officials are tracking the spread of a number of variants of the coronavirus across the U.S., including a much more contagious version first identified in South Africa, another that's rampant in the U.K., and one linked to travelers from Brazil. 

Citing preliminary studies, the CDC said the Pfizer and Moderna vaccines show signs of recognizing and protecting against those variants. 

"I do think that the existing vaccines are going to offer reasonable protection against these new variants," Dr. Scott Gottlieb, former head of the FDA, told CBS' "Face the Nation" in early February, though he added that they are likely to be about 20% less effective against the new strains from Brazil and South Africa. Vaccine researchers are working on developing possible booster shots to combat variants if needed in the future.

South Africa suspended the start of its Oxford-AstraZeneca inoculation program in early February over concerns the shot doesn't work as well against the variant there.

Who shouldn't get a COVID vaccine?

Like most vaccines, this one may not be for everyone. The CDC says people allergic to the ingredient polyethylene glycol (PEG) or polysorbate, which is similar, should not get an mRNA COVID vaccine, and anyone who has an immediate allergic reaction to the first dose should not get the second one.

A handful of people suffered adverse reactions, including anaphylaxis, after getting the vaccine, but all recovered.

People with a history of allergic reaction to a vaccine or injectable therapy for another disease should talk to their doctors, the CDC advises. It says people with food allergies do not need to avoid the vaccine.

Should you get a COVID vaccine during pregnancy?

The CDC, the World Health Organization and the American College of Obstetricians and Gynecologists all advise pregnant patients to talk with a doctor about whether to get a vaccine. Pregnant people were not included in the clinical trials, so data is lacking, and the official guidance has left some confused. Many doctors, however, believe the shots are a good idea because of the known risk of severe illness from COVID-19 during pregnancy.

"I recommend highly that all pregnant women be immunized, from initial discovery of the pregnancy right up to term," Dr. Bob Lahita, professor of medicine New York Medical College and chairman of medicine St. Joseph University Hospital, said on CBSN. He said there is "no evidence" that the vaccine "has any effect on the placenta, on the fetus, on the mother. Except if one gets the infection, the COVID, and you are pregnant, you run the risk of becoming very, very sick."

COVID vaccine trial for pregnant women 08:15

How long will COVID vaccine protection last? 

Researchers and health experts say they don't know for sure. On its official web FAQ, the CDC says, "We won't know how long immunity lasts after vaccination until we have more data on how well COVID-19 vaccines work in real-world conditions."

That said, Moderna CEO Stephane Bancel has offered a rough window: "We believe there will be protection potentially for a couple of years." 

Can you still spread COVID after getting the vaccine?

People who receive a vaccine dramatically lower their chance of getting sick from the virus, but the vaccine trials did not determine whether a person could still be infectious after getting immunized. 

"We just do not know yet the answer to (that) question," said Dr. Jaime Sepulveda, executive director of the Institute for Global Health Sciences at the University of California, San Francisco. "The clinical trials were not designed to have that as an endpoint."

Research on the subject is continuing.

Do I still need to wear a mask after receiving a COVID vaccine? 

Once you've gotten vaccinated it takes about two weeks for the body to develop immunity, so you'll need to continue taking precautions like social distancing and wearing masks to reduce your risk of infection during that time.

After that, the CDC says it is safe for fully vaccinated people to get together indoors, without masks, with others who are also fully vaccinated. But health officials say everyone should continue to wear masks in public places, even after getting the shot. 

COVID-19 vaccine dos and don'ts 05:11

Over time, as more people get vaccinated and infection rates decline, it may become safe to ease up in more situations.

"Eventually I think we won't [need masks], but I think until we know that this vaccine is working, we are going to have to wear a mask," pediatrician Dr. Dyan Hes told CBSN.

What can I safely do after I am fully vaccinated?

Once people are fully vaccinated — meaning two weeks have passed after their final dose — the CDC is assuring Americans that they can can gather, indoors or outdoors, with other fully-vaccinated people without the need to wear a mask or stay 6 feet apart. Vaccinated people can also gather indoors with unvaccinated people from a single household without masks. (That goes for kids, too.)

Vaccinated people no longer need to self-quarantine after travel, though wearing a mask on planes and in other indoor public places is still recommended. The CDC has a more detailed list of do's and don'ts here

Can employers force you to get vaccinated?

The federal government doesn't require vaccinations for anyone. But state and local governments might for their employees. And individual businesses can, in general, impose similar requirements.

"Generally speaking, employers are free to require safety measures like vaccination with exceptions for certain employees," said Aaron Goldstein, a labor and employment partner at the international law firm Dorsey & Whitney. "So the answer is likely to be yes, with an asterisk." Many hospitals, for example,  require staff to get vaccines, with exemptions allowed for medical or religious reasons.

American workers largely back employers making that call. Nearly half of employees — 46% — support their employers requiring COVID-19 shots, according to a survey of LinkedIn users. The survey showed 40% of employees do not support the move and 14% said they were unsure.

COVID vaccine: Concerns between employers & e... 04:36

Do I need to get vaccinated if I've already had COVID?

Even after you've gotten sick from COVID-19 and recovered, you could still get it again; experts do not know how, for sure, long someone might carry antibodies after a bout with coronavirus. So-called natural immunity varies from person to person. The vaccines, on the other hand, provide a reliably high level of protection.

That said: If you were treated with monoclonal antibodies or convalescent plasma during your illness, you should wait 90 days before getting a COVID-19 vaccine. The CDC also recommends you should talk to your doctor before proceeding.

What are the ingredients in COVID vaccines?

The FDA has posted detailed information on its website, including a full list of ingredients for the Moderna, Pfizer and Johnson & Johnson vaccines.

Why are the Pfizer and Moderna vaccines two doses?

For these vaccines to reach maximum effectiveness, two doses are needed. The first injection starts building protection in the immune system. A second shot increases the amount of that protection to more than 90% against the virus.

In reporting on this issue, CBS MoneyWatch senior reporter Stephen Gandel uncovered concerns that getting only one of the two shots might actually make the pandemic worse over time.

"The concern is that if people get one shot, and not two shots, and those people get exposed to the coronavirus, the virus won't get killed off [from] them… and the virus will figure out a way to adapt itself, and then it could spread again. Then we could have a vaccine-resistant strain of the coronavirus out there," he explained.

CDC data from early February showed 96% of people returning for their second shot on or close to schedule, but by late February the number who hadn't returned on time had grown to nearly 3 million people.

How many people need to be vaccinated before we reach herd immunity?

Experts haven't reached a consensus on exactly what it will take for the world to achieve herd immunity — a level of widespread protection that leaves the virus few remaining targets, so outbreaks can no longer flourish. 

The bulk of the U.S. population will need to be vaccinated before it can happen; 50% won't be enough, Dr. Anthony Fauci, the nation's top infectious diseases expert, has said

Millions more doses will be rolling out to vaccination sites and pharmacies across the country in the months ahead, moving us closer to that goal. "By the time we get to April, that would be what I call for lack of better wording, open season. Namely, virtually everybody and anybody in any category can start to get vaccinated," Fauci said.

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