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What to Know About the Coronavirus Vaccines

Questions continue as millions of Americans get immunized

image of a vial labeled coronavirus vaccine

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Researchers around the world have been working at record speed to develop vaccines to combat COVID-19. Less than a year after the start of the pandemic, that goal became a reality.

One vaccine (from Pfizer-BioNTech) has received full approval from the U.S. Food and Drug Administration (FDA) and two others (one from Moderna and another from Johnson & Johnson) are being administered under emergency use authorization (EUA). This FDA designation allows access to treatments and other medical tools during a public health emergency when no other options exist.

The EUA process is faster than standard FDA approval, which can take six to 10 months. However, data proving safety and effectiveness is still required for authorization, and the FDA and an advisory committee of experts use this data to weigh the risks and benefits of the product in question.

What, exactly, is a vaccine?

A vaccine is something that helps a person build up immunity to an infectious disease. It works by intentionally introducing the body to an inactive form of a disease-causing germ, or something similar to it. This then stimulates the immune system’s production of antibodies, the proteins that help to protect the person from a future infection.

Think of it like a workout for your immune system: You’re “sending it to the gym and preparing it to be able to do something," in case it meets up with the germ in the future, explains Tony Moody, associate professor of pediatrics and immunology at the Duke University School of Medicine and a principal investigator at the Duke Human Vaccine Institute. “Essentially, what a vaccine is doing is teaching the immune system how to handle something before you actually encounter the real thing — so that, hopefully, when you do encounter the real thing, you’re able to deal with it quickly and get rid of it,” he says.

In the case of the new coronavirus, a vaccine makes a person resistant to an infection from the virus and the illness it causes — COVID-19 — or, at least, enables a person who becomes infected to have “a shorter course [of disease] or not as many complications,” Moody adds.

What coronavirus vaccines are available now?

The vaccines from Pfizer-BioNTech, Moderna and Johnson & Johnson (J&J) are so far the only products available to Americans. The Centers for Disease Control and Prevention recommends the Pfizer and Moderna vaccines over the J&J vaccine single-shot version because a rare but serious blood clotting disorder has been linked to it. But J&J’s vaccine is still available for people who are “unable or unwilling to receive an mRNA vaccine,” the CDC said in a statement issued Dec. 16. 

Pfizer’s vaccine is approved for people 16 and older and is available for people ages 5-15 under emergency use authorization; Moderna and J&J's vaccines have been authorized for people 18 and older.

The three vaccines lower your risk of getting infected with the virus and have been found to be effective at preventing severe illness from an infection. Unvaccinated individuals are nearly 6 times more likely to test positive for COVID-19 than vaccinated people, and they're 14 times more likely to die from the disease, the latest federal data show.

Are the vaccines safe?

Participants in the Pfizer-BioNTech, Moderna and Johnson & Johnson trials experienced side effects after vaccination, including injection-site pain, fever, chills, headaches, muscle aches and joint pain. These symptoms are usually mild to moderate in severity and are temporary. They are also in line with side effects that some people experience from other vaccines, including the flu shot and the vaccine to prevent shingles.

More serious reactions have occurred but are rare. Anaphylaxis, a severe allergic reaction, has happened in a small number of people after COVID vaccination, the CDC says. This is why you may be asked to wait about 15 minutes after your shot or booster to monitor for symptoms. Vaccines providers are equipped with medicines to quickly treat the reaction. 

Health officials are also monitoring rare reports of myocarditis and pericarditis in some adolescents and younger adults who have received the Pfizer and Moderna vaccines. Most of these patients who received care responded well to medicine and felt better quickly, the CDC says.

Another uncommon event that has been linked to J&J’s vaccine is a rare but serious clotting disorder, called thrombosis with thrombocytopenia syndrome. Fifty-four cases of the condition were confirmed as of August out of about 14 million doses administered; nine people have died from it. Young women in their 30s and 40s are most at risk. After reviewing evidence of the adverse event, the CDC decided on Dec. 16 to recommend Pfizer's and Moderna’s vaccines over J&J’s version. J&J’s, however, is still available to those who are “unable or unwilling” to get the Pfizer or Moderna vaccine.

How much does the vaccine cost?

The federal government pre-purchased hundreds of millions of vaccine doses with taxpayer money, so Americans do not have to pay to receive them, including the booster shots.

Vaccine providers are able to charge an administration fee for giving the shot, but this fee should be covered by public or private insurance or by a government relief fund for the uninsured.

Can I still get COVID-19 after getting the vaccine?

​Because no vaccine is 100 percent effective, breakthrough infections may occur, and more are being reported as omicron rips through the country. But experts stress that the vaccines and booster remain highly protective against hospitalization and death if you do catch COVID. 

Breakthrough infections, however, can contribute to the spread of COVID-19. Data show that fully vaccinated people who become infected with the highly transmissible delta variant can pass the virus on to others, which is why health officials recommend that vaccinated individuals in areas of high community transmission wear a face mask in indoor public settings.


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Do I need the vaccine if I have already had COVID-19?

Even if you had COVID-19, the CDC still recommends getting vaccinated and boosted, since research has not yet shown how long protection from a previous coronavirus infection lasts.  Plus, the vaccine may afford better protection against COVID-19 than a previous infection. Unvaccinated people who already had COVID-19 had greater odds of getting COVID-19 again, compared to fully vaccinated people, a CDC study found

Have questions? Talk to your doctor.

Is it good to have more than one vaccine available?

Absolutely. “In fact, it’s highly desirable,” says William Schaffner, an infectious disease expert and professor at Vanderbilt University School of Medicine, because that would mean “there would be more vaccine manufacturers working to actually produce the vaccine, and so we could more expeditiously try to vaccinate the population in the United States and beyond.”

Kathleen Neuzil, M.D., professor in vaccinology and director of the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine, echoes Schaffner’s sentiment and points to the flu vaccine for comparison: There are multiple formulations on the market, including the injectable high-dose vaccine and the nasal spray vaccine, for example, which are recommended for different populations.

“We really need every person on Earth, theoretically, to be able to receive this vaccine. So, to me, [having more than one option] is a positive, because we need so much,” she adds.

Editor’s note: This article, originally published May 1, 2020, has been updated to reflect new information.