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What to Know About the Coronavirus Vaccines

Questions continue as millions of Americans get immunized and boosted

Photograph of a medical vial labeled coronavirus vaccine, injection only, 5 ml
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Latest updates


  • COVID-19 vaccine from Novavax gets FDA authorization and CDC sign-off. Roughly one week after the Food and Drug Administration (FDA) granted Novavax’s COVID-19 vaccine emergency use authorization, the Centers for Disease Control and Prevention (CDC) signed off on its use, making the vaccine the fourth one available to Americans in the fight against COVID-19. The two-shot series from Novavax, cleared for adults 18 and older, will be available in the coming weeks. It uses a different, more traditional, technology than the other COVID-19 vaccines on the market. Instead of prompting the body to make its own version of the spike protein (a key part of the virus), the protein is made in a lab and then delivered directly upon injection. “If you have been waiting for a COVID-19 vaccine built on a different technology than those previously available, now is the time to join the millions of Americans who have been vaccinated,” CDC Director Rochelle Walensky said. “With COVID-19 cases on the rise again across parts of the country, vaccination is critical to help protect against the complications of severe COVID-19 disease.”

  • Health officials urge older adults to stay up to date on vaccines with arrival of BA.5. Health officials on July 12 encouraged adults 50 and older to get their second booster shot if they haven’t already. Doing so will ramp up protection against the highly contagious BA.5 variant, which is now the dominant strain circulating in the U.S. Officials say BA.5 “may have some increased ability to escape immunity, including from prior infections, meaning it has the potential to cause the number of infections to rise in the coming weeks.” Cases of COVID-19 are once again climbing; so are hospitalizations. “If you’re over 50, that extra booster dramatically lowers your risk of getting into the hospital, going to the ICU and dying,” said White House COVID-19 Response Coordinator Ashish Jha. The latest data show that among those 50 and older, people who have received two booster shots are 42 times less likely to die from COVID-19 compared to those who are unvaccinated. So far, less than one-third of adults 50 and older have received their second COVID-19 booster shot, federal data shows. What’s more, getting the booster now won’t preclude you from getting an updated version of the vaccine later this fall. The U.S. Food and Drug Administration (FDA) has asked both Pfizer and Moderna to make a COVID-19 vaccine that targets the original coronavirus strain, as well as omicron, including omicron’s BA.4 and BA.5 subvariants.

  • CDC recommends vaccinations for young children. Rochelle Walensky, M.D., director of the Centers for Disease Control and Prevention (CDC), recommended on June 18 that parents vaccinate their young children ages 6 months to 5 years, accepting the findings of the FDA and CDC’s vaccine advisory committee. “I encourage parents and caregivers with questions to talk to their doctor, nurse or local pharmacist to learn more about the benefits of vaccinations and the importance of protecting their children by getting them vaccinated,” Walensky said in a statement. The FDA on June 17 authorized the Pfizer-BioNTech and Moderna vaccines for that youngest age group and also authorized Moderna’s vaccine for youth ages 6 to 17. Distribution of pediatric vaccinations for the youngest children has started across the country, CDC officials say, and doses are available at thousands of pediatric practices, pharmacies, federally qualified health centers, local health departments and clinics. In May, health officials had recommended that kids 5 and older who have been vaccinated with Pfizer’s two-shot series get a booster.
  • COVID takes 1 million U.S. lives. The number of Americans who have died from COVID-19 reached 1 million on May 16. This grim milestone eclipses the impact of other catastrophes in our nation’s history. The deaths equal more than twice the American military casualties of World War II (405,399), the Vietnam War (58,220) and the terrorist attack on 9/11/2001 (2,977) — combined. These American fatalities are also higher than the 657,000 who perished in the flu of 1918, also known as the Spanish flu, and the more than the 700,000 who have died from HIV/AIDS since 1981. “The fact that more than 90 percent of the 1 million COVID deaths in the U.S. over the last two years have been among those ages 50 and older spotlights the urgent need to address how we support health as we age going forward,” said AARP CEO Jo Ann Jenkins. While 1 million deaths is an overwhelming number, the breakneck development of three coronavirus vaccines that have fully immunized nearly 220 million Americans has prevented an estimated 2.2 million more fatalities from this virus, according to a Commonwealth Fund report. Yet, while hospitalizations and deaths are far lower than they were this past winter, federal health officials and medical experts are quick to point out that this pandemic is not yet behind us. And that is particularly true among Americans who are most at risk for the coronavirus: older adults, those with compromised immune systems and people with such underlying medical conditions as diabetes and respiratory illnesses.

  • ​​FDA restricts use of Johnson & Johnson COVID vaccine. Americans 18 and older who still have not been vaccinated against COVID-19 should only get the Johnson & Johnson shot if the Pfizer-BioNTech and Moderna vaccines are not available or medically appropriate, or if getting the J&J product is the only way they will get vaccinated, federal regulators said on May 5 in an update to the vaccine’s emergency use authorization. The reason, the U.S. Food and Drug Administration (FDA) noted in its announcement, is due to a rare but potentially life-threatening complication called thrombosis with thrombocytopenia syndrome (TTS), which was first linked to the J&J vaccine in the spring of 2021. Health officials have since been monitoring and investigating all cases of TTS, which develops when blood clots form and an individual also has low levels of blood platelets. The majority of cases — there have been 60 as of March 2022 — have been in women; most have been younger than 50. TTS has not been linked to the Pfizer-BioNTech and Moderna vaccines, which use an mRNA technology different from J&J’s. The CDC in December recommended the mRNA vaccines over J&J’s product “in most situations.”
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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.

Two vaccines (from Pfizer-BioNTech and Moderna) have received full approval from the U.S. Food and Drug Administration (FDA) and two others (from Johnson & Johnson and Novavax) are being administered under a limited 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.

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, M.D., 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.

What coronavirus vaccines are available now?


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The vaccines from Pfizer-BioNTech, Moderna, Johnson & Johnson (J&J) and Novavax are so far the only products available to Americans. The Centers for Disease Control and Prevention (CDC) 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 says.

Pfizer’s vaccine is approved for people 16 and older but is available for people ages 6 months through 15 years under emergency use authorization. Moderna’s vaccine is also authorized for kids 6 months and up and is approved for people 18 and older. Both vaccines from Novavax and J&J are authorized for people 18 and older.

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The four vaccines lower your risk of getting infected with the virus and have been found to be highly effective at preventing severe illness from an infection. Hospitalizations in May 2022 were 3.8 times higher in unvaccinated individuals ages 65 and older, compared to their vaccinated and boosted peers, federal data shows.

Are the vaccines safe?

Participants in the clinical trials testing the vaccines 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. Sixty cases of the condition were confirmed as of March; nine were fatal. 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; months later, the FDA limited its use. J&J’s vaccine, 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.


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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 can occur, and more are being reported as omicron and its subvariants rip through the country. But experts stress that the vaccines and boosters remain highly protective against hospitalization and death if you do catch COVID-19. 

Breakthrough infections, however, can contribute to the spread of COVID-19, which is why health officials recommend that vaccinated individuals in areas of high community transmission wear a face mask in indoor public settings.

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, 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, M.D., 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.


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