Fact Check: Is the COVID-19 Vaccine Safe?

By Kate BoveLast Updated May 14, 2021 11:33:21 AM ET
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Photo Courtesy: Craig F. Walker/The Boston Globe/Getty Images

Over the course of 2020, the world’s leading scientists and researchers worked tirelessly to engineer COVID-19 vaccines. And, heading into 2021, the U.S. Food and Drug Administration (FDA) provided many Americans with much-needed hope after issuing Emergency Use Authorization for both the Pfizer and Moderna vaccines. Although AstraZeneca’s candidate has yet to join them, a third vaccine developed by Janssen — a Johnson & Johnson company — earned emergency use authorization from the FDA in late February 2021. Without a doubt, the rapid development of these vaccines is an unprecedented achievement. But this sense of triumph (and relief) has been marred by the conversation surrounding the vaccines’ safety.

As reported in U.S. News & World Report, a 2020 Gallup survey found that 11% of adults in the U.S. believe vaccines are "more dangerous than the diseases they prevent." While this survey was conducted before the novel coronavirus pandemic made headlines in the U.S., it’s undeniable that the vaccine rollout is happening amid a climate of mistrust and misinformation. Even though the FDA has deemed the three vaccines "safe and effective," many Americans are still hesitant when it comes to vaccination. With this in mind, we’re taking a look at some of the most common concerns when it comes to the COVID-19 vaccine in our latest Fact Check.

Editor’s Note: Our research pertains to the Pfizer, Moderna and Janssen (colloquially called Johnson & Johnson) COVID-19 vaccines only. We will update this information as others are approved for use.

Does Getting Vaccinated Mean Life Can Return to “Normal”?

For over a year, many of us have dreamed of a time when going maskless at the grocery store feels safe again. And the CDC says that time is now. On Thursday, May 13, federal health officials stated that fully vaccinated Americans could stop wearing masks or maintaining social distance in most settings. To be clear, individuals are considered fully vaccinated two weeks after their last shot.

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Photo Courtesy: Joe Raedle/Getty Images

It's important to note that this CDC guidance does not override state, local or tribal laws. Moreover, business owners and offices can still require mask usage. In fact, even the federal government may still require mask-wearing in certain situations. Nonetheless, this is a huge next step. “Permission to stop using masks also offers an incentive to the many millions who are still holding out on vaccination,” The New York Times points out. “As of Thursday, about 155 million people had received at least one dose of a Covid-19 vaccine, but only about one-third of the nation, 119 million people, had been fully vaccinated.” 


But there’s no doubt that what was meant to be a big relief has left many Americans feeling uncertain. Not only has the new recommendation caught local officials and business owners by surprise, it has even caught those of us dreaming of a far-off maskless future by surprise. In fact, a survey, which was conducted by The New York Times just two weeks before this new guidance broke, showed that hundreds of epidemiologists had anticipated that mask-wearing would remain the norm for at least another year. 

So, what else can fully vaccinated individuals do? According to the CDC, the following is advised:

  • You can resume activities that you did prior to the pandemic.
  • You can resume activities without wearing a mask or staying 6 feet apart, except where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance.
  • If you travel in the United States, you do not need to get tested before or after travel or self-quarantine after travel.
  • If you’ve been around someone who has COVID-19, you do not need to stay away from others or get tested unless you have symptoms — unless you live or work in a correctional or detention facility or a shelter for unhoused folks.

How Do the Vaccines Work?

Although there are quite a few different methods for developing vaccines, both the Pfizer and Moderna variations are made using the same technology — a new technology, in fact, that utilizes mRNA. Think back to high school biology for a moment: You might remember that DNA is the carrier of genetic information and that the similarly named mRNA (or messenger RNA) is essentially a set of instructions that tells the body how to make certain proteins to fight and prevent disease.

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Photo Courtesy: Eric Lee/Bloomberg/Getty Images

Once a recipient receives an mRNA vaccine, it tells their cells to create a viral protein that triggers an immune response. Unlike other vaccines, which use weakened or similar forms of a virus to trigger these responses, there is no live virus involved here, which means the vaccine can’t cause COVID-19 because it simply doesn’t contain the novel coronavirus. Instead, the vaccine teaches our immune systems to recognize and fight the virus to protect us from future exposure.


Instead of using the mRNA method, the Johnson & Johnson formulation modifies an existing adenovirus — something that normally causes colds — by inserting the novel coronavirus’ spike protein into it. While this modified adenovirus can’t reproduce in the human body or cause COVID-19, it does help your body prepare antibodies in advance, which means your immune system will be ready should you actually contract the novel coronavirus.

Are the COVID-19 Vaccines Safe?

Before a vaccine is deemed safe, it goes through what the Centers for Disease Control and Prevention (CDC) calls "rigorous" testing. Initially, safety trials start in the lab, where experts run tests on (and research) cells and animals — and that’s all before human studies are given the greenlight.

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Photo Courtesy: Eric Lee/Bloomberg/Getty Images

Additionally, CDC guidelines require that "vaccines pass through six general stages of development: exploratory, pre-clinical, clinical, regulatory review and approval, manufacturing, and quality control. ...It’s not unusual for a vaccine to take 10 to 15 years to complete all the phases under normal circumstances." Obviously, these are not normal circumstances. Although speeding up the development process was necessary, leading experts, including Dr. Anthony Fauci, stated that attempts to fast-track a vaccine should not supersede the fact that a vaccine must be both safe and effective before distribution.

For example, Pfizer ran its own tests and clinical trials that included more than 44,000 adult participants, while Moderna ran a 30,000-person efficacy trial. After these trials and the FDA’s own analysis, which found "no specific safety concerns," the vaccines were authorized for emergency use. Dr. Fauci has gone on to say that he has "extreme confidence" in the safety of the approved vaccines and even received the Moderna vaccine on camera in late December 2020.


Is It Safe for Children to Receive the Vaccine?

When the vaccines were initially rolled out, Pfizer's vaccine had been approved for folks age 16 and up, while Moderna's had been approved for folks age 18 and up. For awhile, that meant anyone younger was unable to seek vaccination — but that all changed in May 2021.

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Photo Courtesy: Al Seib/Los Angeles Times/Getty Images

On May 10, the FDA expanded the emergency use authorization of the Pfizer vaccine, so that adolescents 12-15 years of age can now receive their shots. Two days later, the CDC endorsed the FDA’s statement. Before these expanded approvals, pediatric specialists, such as Connecticut Children’s, reiterated that "young adults and kids aren’t typically at high risk for severe illness from COVID-19." Nonetheless, now that the Pfizer vaccine has been deemed safe for younger individuals, the CDC and FDA believe this is an important next step.


“For vaccination to do its job, we must do our critical part. That means vaccinating as many people as possible who are eligible. This official CDC action opens vaccination to approximately 17 million adolescents in the United States and strengthens our nation’s efforts to protect even more people from the effects of COVID-19," the CDC statement noted. "Getting adolescents vaccinated means their faster return to social activities and can provide parents and caregivers peace of mind knowing their family is protected.”

In April, There Was a Pause on the Johnson & Johnson Vaccine — But Why?

As for Johnson & Johnson vaccine, the CDC initially stated that it "has been shown to meet all requirements for Emergency Use Authorization," thus making it another key player in helping to prevent severe COVID-19 illness, hospitalization, and death. But on April 13, 2021, the CDC and the FDA released a joint statement that recommended the U.S. pause its distribution of Johnson & Johnson vaccines.

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Photo Courtesy: Tom Williams/CQ-Roll Call, Inc./Getty Images

The now-revoked recommendation came in the wake of six reports of a "rare and severe" type of blood clot that occurred in women between the ages of 18 and 48. These six patients reported symptoms 6 to 13 days after receiving the Johnson & Johnson vaccine. The joint statement also noted that the adverse side effects were "extremely rare" — after all, 6.8 million doses of the Johnson & Johnson vaccine had been administered in the U.S. when the pause occurred.

By April 23, 2021, the CDC and FDA lifted the recommended pause following "a thorough safety review." Moreover, while the risk of developing a blood clot due to the vaccine remains incredibly low, the two agencies have vowed to remain vigilant.


"Safety is our top priority. This pause was an example of our extensive safety monitoring working as they were designed to work—identifying even these small number of cases," said Janet Woodcock, M.D., Acting FDA Commissioner. "We are confident that this vaccine continues to meet our standards for safety, effectiveness and quality."

In the rare case you develop a "severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination," or if you have any additional questions, the CDC and FDA recommend reaching out to your health care provider.


Does the Vaccine Have Any Side Effects?

No matter the vaccine — and no matter what a vaccine is fighting against — injection is often accompanied by mild side effects, including fatigue, swelling, pain and redness at the injection site, all of which usually clear up within 24 hours. In fact, these types of side effects "show that the vaccine is working, because it stimulates the immune system and the body forms antibodies against the infection that is only ‘feigned’ by the vaccination."

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Recently, the Finnish Medicines Agency (FIMEA) found that headaches, mild fever and joint pain can accompany the COVID-19 vaccines; in particular, incidences of fever have been found to be higher after the second dose of the Pfizer vaccine. Additionally, organizations like the CDC and FDA will continue to monitor vaccine safety to catch and address emerging trends in adverse effects. As of now, however, there’s no evidence to indicate that the Pfizer and Moderna vaccines cause any long-term or harmful side effects, and less than 1% of Pfizer vaccine recipients had severe allergic reactions.


Is One Vaccine “Better” Than the Other?

While it's unlikely that individuals will be able to choose between the vaccines, folks are still wondering if one is better than the others. First, let's compare the mRNA vaccines. While the Pfizer vaccine is authorized for individuals age 16 and older, the Moderna vaccine is authorized for individuals age 18 and older; Pfizer boasts a 95% efficacy rate across different racial, ethnic, gender and age groups, whereas Moderna boasts a 94% efficacy rate.

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In terms of administering the vaccine, both require two rounds of doses: Pfizer vaccines require a 21-day interval between shots, whereas Moderna’s require a 28-day interval. Although the Pfizer version contains 30 micrograms of the vaccine — compared to Moderna’s 100 micrograms — it is getting slightly better efficacy results, but at a cost.


That is, according to Stat, the Pfizer vaccine must be stored at -94 degrees Fahrenheit and, after thawing, it must be administered within five days. In this regard, Moderna’s variation seems to have a slight edge: It should be shipped at a more manageable -4 degrees Fahrenheit but can be stable at fridge temperature for 30 days. All things considered, the two vaccines are quite comparable, and receiving immunization from either is a great step toward ending the devastation of the COVID-19 pandemic.

What About the Janssen (Johnson & Johnson) Vaccine?

While this third vaccine, which is authorized for individuals 18 and older, doesn't boast the same efficacy rates as the Pfizer and Moderna formulations, it's still extremely effective. In the first 14 days after vaccination, the Janssen vaccine is roughly 77% effective in preventing severe or critical forms of COVID-19; after 28 days, that effectiveness jumps to about 85%. Does this sound low? Well, it's worth noting that the flu shot is often around 60% effective.


With this in mind, the CDC has called the Janssen vaccine "another important tool in our toolbox to equitably vaccinate as many people as possible" — and for good reason. First and foremost, the Janssen vaccine is just one dose, which means patients don't need to make follow-up appointments to receive the vaccine's full benefits. Additionally, the one-dose formulation doesn't need to be kept in a freezer, which makes storing and transporting it less of a logistical nightmare.

The CDC states that the comparative ease of moving this vaccine "allows for expanded availability in most community settings and mobile sites, as supply scales up." In fact, President Joe Biden has echoed these sentiments, stating that the partnership between Johnson & Johnson and would-be competitor Merck will ramp up supply of the Janssen vaccine so much that the U.S. should have enough vaccines to vaccinate all adults by the end of May 2021, which would greatly change the country's landscape.


Can You Still Contract or Spread COVID-19 After Getting Vaccinated?

Both the Pfizer and Moderna vaccine formulations are remarkably effective, with a 94-95% efficacy rate. Additionally, the single-dose Janssen vaccine boasts an impressive 85% efficacy in regards to preventing severe cases of COVID-19. That is, while it may not boast the same numbers as the other vaccines, Janssen's formulation will curb hospitalizations and fatalities, which is the main goal behind mass vaccination.

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Photo Courtesy: Michael Ciaglo/Stringer/Getty Images

Additionally, the vaccines are being rolled out in phases in most states: If you have been fully vaccinated but come into contact with someone who isn’t, that could be dangerous for the unvaccinated person. Long story short, getting a vaccine doesn't mean you're completely immune to contracting (or spreading) COVID-19. However, widespread vaccination will help build herd immunity — a state at which enough people are immune to the virus that spreading the pathogen from person to person becomes less common.


Should People Who Have Had COVID-19 Still Get Vaccinated?

A resounding "Yes" from the CDC and other healthcare experts on this one. Re-infection is possible, so if the vaccine is offered to you, regardless of whether you’ve already had COVID-19, you should get vaccinated. It’s still unclear how long immunity lasts and, in general, the length of a person’s natural immunity can vary greatly.

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Photo Courtesy: Joseph Prezioso/AFP/Getty Images

Currently, the CDC is providing recommendations to federal, state and local governments as to which groups of people should be vaccinated first. If you’re part of one of those early-stage groups, vaccination is important regardless of your history with COVID-19, and health officials recommend the extra safety precaution. "Both natural immunity and vaccine-induced immunity are important aspects of COVID-19 that experts are trying to learn more about," the CDC has stated. "And [we] will keep the public informed as new evidence becomes available."


Should Pregnant or Lactating Individuals Seek Vaccination?

If an individual is pregnant or lactating, the guidance has been a little less clear. The CDC notes that pregnant people with COVID-19 have an increased risk of severe illness and, potentially, an increased risk of adverse pregnancy outcomes. With this in mind, getting vaccinated does seem important because pregnant people are particularly vulnerable.

More recently, preliminary results from two ongoing studies have shown that the Pfizer-BioNTech and Moderna coronavirus vaccines are safe and effective during pregnancy. Nonetheless, the CDC still recommends individuals consult with their doctors before choosing to get vaccinated.


Finally, the CDC states that "There are no data on the safety of COVID-19 vaccines in lactating people or the effects of mRNA COVID-19 vaccines on the breastfed infant or milk production/excretion." However, there isn’t evidence to suggest that a vaccine would cause harmful effects in lactating individuals.

Should Immunocompromised Individuals Seek Vaccination?

Similarly, although some clinical trials did include folks with stable HIV infection or other immunocompromising conditions, there still isn’t a lot of data, so consulting with a doctor or other healthcare provider is recommended. In most cases, seeking vaccination is up to an individual's comfort level and doctor's recommendation.