10 of the most common concerns about the Covid-19 vaccines

Worth the shot.
Worth the shot.
Image: Reuters/Mark Lennihan
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You trust science. You trust scientists. You believe that Covid-19 vaccine candidates, like other vaccines, have been properly tested, and trust health authorities to weigh the evidence for them carefully. You know that the fastest way to end the pandemic is through immunization, and you were thrilled to watch the first vaccinations go out.

And yet. You might still find yourself pausing, instinctively, over concerns about Covid-19 vaccination. You don’t have to reject the importance and safety of vaccines to have questions.

So Quartz collected many of the questions and doubts that you might have, and addressed them with the help of experts. We hope they make you feel more confident navigating this unprecedented time, whether you’re thinking about your own Covid-19 vaccination or that of a loved one. Our collective future depends on it.

Were the Covid-19 vaccines rushed through?

Nine months ago, predictions that we might have the vaccine before the end of the year were dismissed by experts as wishful thinking. But the development timeline caught us off guard: It blew past even the most optimistic forecasts, which had suggested the vaccine wouldn’t be available before 2021.

But while it is true that in order to get the vaccine this quickly some of the trial phases have been compressed—primarily by running different phases of the trial in parallel rather than waiting to complete each before getting to the next—this doesn’t mean that the trials didn’t assess the safety of the vaccine, or its efficacy. Independent public health bodies in different countries have examined the results of those trials before authorizing vaccines for emergency use.

As Lynda Stuart, deputy director for vaccines at the Bill and Melinda Gates Foundation says, it’s important to remember that one of the reasons the vaccine was developed at such speed was the unprecedented collaboration of the global scientific community. This means, too, that the efficacy and safety of vaccines will be established and accepted by a large scientific community.

Further, the parameters applied for emergency authorization have not been changed. In the US and EU, in particular, authorities resisted pressure to speed up the review timeline, knowing well the trust of citizens would be compromised if they failed to note possible risks.

There are questions the trials have not yet answered. We don’t know how long vaccine-derived immunity will last, or whether people who get vaccinated can still transmit the virus. We also don’t have data on the effects of the vaccine on pregnant individuals or children. Gathering these data depends on continuing the existing trials, and running new ones on expanded populations.

Can I trust the governments that authorized vaccines?

The process for approving drugs has almost nothing to do with the government in power at the time of their approval. Each country (or group of countries, like the EU) has a designated regulatory authority to review potential new drugs and vaccines.

In the US, for example, that body is the US Food and Drug Administration (FDA). In order for a new Covid-19 vaccine to be authorized for public use, companies first need to present clinical trial data (here’s Pfizer’s, and here’s Moderna’s) to an advisory committee stacked with vaccine experts, which votes on whether to recommend the vaccine for FDA authorization. Shortly thereafter, other scientists at the FDA vote on whether or not to take that committee’s advice.

If a vaccine receives authorization, yet another group of scientists at the US Centers for Disease Control and Prevention (CDC) has a meeting to recommend which populations that should receive the authorized vaccine. Although the current president appoints the head of the FDA and CDC who are later confirmed by the Senate, they don’t impact the final decisions of all of these committees.

Most other countries have a similar regulatory authority in place. In the UK, that authority is called the Medicines and Healthcare Products Regulatory Agency; the EU has the European Medicines Agency; China has the National Medical Products Administration; and Russia has the Federal Service for Health Supervision of Russia.

Is the Covid-19 vaccine dangerous for people with allergies?

In the first round of shots of the Pfizer/BioNTech Covid-19 vaccine, a limited number of recipients have had severe allergic reactions, requiring treatment with epinephrine. Some of these people had a history of severe allergic reactions, and already carried EpiPens.

Severe allergic reactions can be life-threatening if untreated, but if they’re caught in time, can be fully treatable. That’s why UK health officials now recommend that doctors monitor patients for 15 minutes after receiving the vaccine to watch for reactions, and that anyone with a history of anaphylaxis should not receive the vaccine.

When FDA first authorized the vaccine for use on Dec. 11, it initially suggested that clinicians not administer that vaccine to patients with a history of anaphylaxis, but it has since reversed its decision. People who know they are allergic to one of the ingredients in the vaccine, which Pfizer and BioNTech have listed in full (pdf), should not receive the shot.

No one’s sure yet which ingredient in the Pfizer-BioNTech vaccine caused these rare but significant allergic reactions. A stabilizer called polyethylene glycol has caused rare but severe allergic reactions in the past, so some medical professionals suspect this is the allergen in the new vaccine. But without further testing, it’s impossible to know for sure.

Are the vaccines safe for my racial or ethnic group?

The first Covid-19 vaccine delivered in the US was administered by a Black health worker, Michelle Chester, to a Black health worker, Sandra Lindsay, in a hospital in Queens. The photograph showing the moment the vaccine was administered became a symbol of hope worldwide. It’s an important image—the two women reflect the representation of minorities both in the healthcare workforce, as well as in the patients hit hardest by the coronavirus, and is most at risk of severe cases of Covid-19. But there is another reason Lindsay agreed to be the first to receive the vaccine—she wanted to be an example and help fight vaccine hesitancy among people of color.

The history of Western medicine is marked by racism, and racial disparities in care continue through the present. Communities of color have been hit hardest by the coronavirus, and are also the most at risk of severe cases of Covid-19. While trials and medical practices are slowly acknowledging and addressing racial inequalities, much work remains to be done—including on trial design.

Black people and people of Asian ancestry were underrepresented in the trials. In the Pfizer vaccine phase 3 trial, for instance, only 4.2% of subjects were of Asian origin, and 9.2% Black. However, this doesn’t mean the vaccine presents higher risks for members of ethnic minorities, and they have no reason to worry that they might experience different or worse side effects than white ones.

In fact, medical representatives of different ethnicities are encouraging minorities to get the vaccine, not only because it is safe for them but also, as Salman Waqar, a physician and researcher at Oxford highlights, because communities of color have been hardest hit by the pandemic and need to access as much protection against Covid-19, as soon as possible, as they can.

Will a Covid-19 vaccine give me Covid-19?

Vaccines don’t give you a disease; instead, they teach your immune system how to fight off one they may encounter in the future. They introduce a benign form of a virus or bacteria—or even just a key part of a pathogen—so if you ever encounter the real one, you’ll already have some defenses at the ready.

The Pfizer and Moderna vaccines specifically use mRNA, a genetic code that helps your body build proteins that look like the SARS-CoV-2 virus. These proteins get released into the body, which cause immune cells to think they’re under attack. Our immune cells spring into action and make protective antibodies that work against the real virus.

In other words, mRNA vaccines use our own bodies to build the protein that ultimately triggers this protective immune response. There is no way that this protein alone could cause you to develop Covid-19.

Can Covid-19 vaccines cause infertility, and are they safe during pregnancy?

Pregnant people are clearly in need of some extra protection from Covid-19. In the past few months, the CDC noted that pregnancy is a risk factor for the virus, increasing the likelihood of severe forms of the disease and death. But no pregnant person was part of Pfizer’s clinical trial—as is the case with most trials, since it’s generally not considered ethical—so there’s no data on how safe it would be for them.

Neither the CDC nor the FDA has recommended that pregnant people get the vaccine. Still, the American College of Obstetricians and Gynecologists (ACOG), among other groups, has pushed for pregnant people to be given access to the vaccine if they want it.

As the vaccine rolls out among the general population, experts will gather more information about side effects and overall safety for pregnant vaccine recipients. In the meantime, misinformation has spread about a nonexistent link between fertility and the Covid-19 vaccine. One such piece of misinformation, for instance, states that the Pfizer/BioNTech vaccine would train the body to attack a protein that is important in the formation of the placenta. This is completely unfounded, and based on a lack of understanding not only of how mRNA vaccines work, but also on the structure of the placenta protein it would threaten. “It’s a myth, it’s inaccurate—there’s no evidence to support their perception,” Saad Omer, a vaccine expert at Yale University, told the New York Times.

If I am breastfeeding, is the Covid-19 vaccine safe for my baby?

Similarly to pregnancy, the effects of the vaccine on breastfeeding have not been studied in clinical trials. But there is no reason to think the vaccine could have any negative effects on lactation. ACOG has issued the same guidelines for breastfeeding as it has for pregnancy: Individuals should be given the option to get the vaccine, but also supported if they wish not to.

If I was already exposed to Covid-19, do I need a vaccine?

Scientists still aren’t sure how much protection a person who has had Covid-19 has against getting it in the future. There have been reports of some people getting a second Covid-19 infection; this suggests that at least some people do not produce enough protective antibodies against the virus to avoid reinfection, or that their antibodies dwindle after a time. Other people, like those who have gotten more severe cases of Covid-19 or those who have donated convalescent plasma, may have more robust protective antibodies.

But still, “they probably will need [the vaccine],” says Juanita Mora, an immunologist practicing in Chicago and volunteer medical spokesperson with the American Lung Association. Healthcare providers can’t yet say if someone who has recovered from Covid-19 will be safe from future infections. Plus, even if a person did have adequate protective antibodies, a vaccine would merely boost that protection—which won’t hurt. “We want everyone to be on the same page as we get to herd immunity,” Mora says.

Will the Covid-19 vaccine cause side effects?

Most of the side effects reported with Covid-19 vaccines are similar to what some people experience with flu shots or other immunization jabs—pain at the place of injection, chills, muscle aches, and fever. Fewer than 2% of the participants in the Pfizer trials reported severe versions of those symptoms, and those reactions were more common after receiving the second dose; severe side effects occurred at similar rates in the Moderna trials.

Mild, moderate, or severe, those common side effects should go away after a day and a half at most, Mora says. These are signs that the body producing an immune response—which is the point of a vaccination in the first place. Side effects don’t have to happen in order for a vaccine to be doing its job, however.

The only severe side effects reported so far for vaccine deployed in the general population have been instances of anaphylaxis—but that’s very rare.

Will mRNA vaccines change my DNA?

The Pfizer/BioNTech vaccine uses a form of genetic material called mRNA, but it only ever interacts with our cellular machinery outside of the nucleus, the extra protective bubble where our cells store their DNA. mRNA acts as a messenger to translate information from our DNA into proteins, so even if the mRNA from the vaccine did make its way into the nucleus, it wouldn’t be able to alter our DNA. Some studies have shown that mRNA degrades within our cells after a matter of hours; it sticks around to do its job producing proteins to trigger an immune response, but then gets broken down as cellular waste.