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Your COVID-19 Vaccine Questions, From Side Effects to Safety

When experts first began talking about developing a coronavirus vaccine, they said it would take a minimum of two years. Less than a year after California issued a stay-at-home order, the vaccine is here. And that’s one reason some people have questions about it.

We’ve searched for and compiled answers to some of the most frequently asked questions health experts are hearing. Our answers come from a live Q&A with the Exploratorium featuring Dr. Bob Wachter, chair of the UCSF Department of Medicine, and Dr. Kirsten Bibbins-Domingo, chair of the UCSF Department of Epidemiology and Biostatistics. We also consulted the Centers for Disease Control and Prevention, the Food and Drug Administration, the World Health Organization and various other medical associations and journal articles. For those of you who want to dig deeper, we’ve linked to some of those.Jump to a question:

How were the vaccines developed so quickly? How do people know the vaccines are safe and effective? What are the possible side effects of getting a vaccine? But the FDA approved this vaccine after two months of observation; isn’t there a chance a really bad side effect could show up much later? Why do you need multiple doses and how long does your immunity last? Does an mRNA vaccine give me the virus? Do the vaccines work against the variants? Can you still get and transmit COVID-19 if you’ve been vaccinated? Should you get vaccinated if you’re pregnant or breastfeeding? Were the vaccines tested on racially and ethnically diverse populations? Were they effective for a range of races/ethnicities? What are the differences between the Moderna and the Pfizer-BioNTech vaccine? Is one better than the other? Are the vaccines safe for all ages? Why should young people get vaccinated? Should I get vaccinated if I already had COVID-19? And how long should I wait after I’ve had COVID-19 to get it? If I’m vaccinated, can I stop wearing a mask and get close to people again? I am immunosuppressed, should I still get the vaccine? Do the COVID-19 vaccines cause infertility? Does the vaccine allow any authority to track me? How do I get the vaccine?

Q: How were the vaccines developed so quickly?

U.S. government agencies and private companies collaborated on a project called Operation Warp Speed to fast-track the coronavirus vaccine. This accelerated timeline doesn’t mean any steps were skipped in the testing stages for the vaccines. The shortcuts related to funding and to dialogue and planning, which went quickly since everyone had the same goal.

Normally, companies don’t manufacture any vaccine doses until they’re in the approval process. It’s a big risk to invest a lot of money in manufacturing without knowing whether the vaccine will be approved. But under Operation Warp Speed, governments pre-paid for the vaccines to eliminate the financial risk for the companies involved. This allowed them to manufacture the vaccine at the same time they were doing the testing. So when the testing was complete, a lot of doses were already available to distribute.

Another reason for how quickly these vaccines were developed is that mRNA vaccines aren’t new; they had already been studied for years and were being developed for other infectious diseases. Because of this, researchers already knew how to make an mRNA vaccine and could customize development and testing for SARS-CoV-2.

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Q: How do people know the vaccines are safe and effective?

Pfizer and Moderna didn’t skip any steps in the stages of testing for the vaccines’ safety and efficacy. The stages include testing in animals and an application for FDA approval to test in humans. Then the drug companies tested the vaccine in a small number of individuals before conducting tests in tens of thousands of people.

The only part of this process that was shorter than usual was in how long Moderna and Pfizer observed people for long-term side effects before requesting FDA authorization to distribute the vaccine.

“They would normally wait, let’s say, six months after testing of the vaccine,” Dr. Wachter said. “They waited two months, and why? Because this was an absolute emergency and a catastrophe. And so in waiting extra months, there would have been hundreds of thousands of people that would have died.”

The FDA was asking for a minimum of 50% efficacy against the coronavirus. After two doses, Pfizer-BioNTech’s vaccine is 95% effective at preventing the symptoms of COVID-19 and Moderna’s is a little over 94%. Those results and the safety records are why the FDA authorized the emergency use of both vaccines.

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Q: What are the possible side effects of getting a vaccine?

The possible short-term side effects for both vaccines include pain, swelling and redness at the injection site, as well as tiredness, chills and headaches. If you get side-effects, they would typically start within a day or two of injection and last a few days. The side effects, experts note, are your immune system telling you the vaccine is working and your body is creating antibodies.

If you find yourself experiencing these side effects, consult your doctor before taking over-the-counter medication such as ibuprofen, aspirin, antihistamines, or acetaminophen. Also, don’t take these medications before you get the vaccine.

The CDC reports that a December study found that a small fraction of people — 11.1 recipients per million doses administered — had a severe allergic reaction called anaphylaxis, which can be lethal. The CDC has listed a few allergies that could prevent someone from getting the vaccine. The agency also recommends people get screened for allergies before receiving the vaccine, and that vaccine sites have epinephrine injections available. If you have allergies, you may wish to consult your doctor about the vaccine.

There are two systems that allow you or your doctor to report any unusual side-effects to officials at the CDC and elsewhere: V-safe and VAERS.

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Q: But the FDA approved this vaccine after two months of observation; isn’t there a chance a really bad side effect could show up much later?

According to experts, says Dr. Wachter, in the history of vaccines there have been no instances of a serious, worrisome side effect that didn’t show up in the first two months. So while no one is saying it’s impossible for a long-term side effect to emerge later, both Dr. Wachter and Dr. Bibbins-Domingo say the risk of that is not even close to the risk of contracting COVID-19 and dying or ending up with long-term physical problems.

“It’s certainly not a close call, especially when you look at the surge in California, and also when you look at how much we really are still learning about how much the coronavirus affects the body,” said Dr. Bibbins-Domingo. “People should talk to their doctors, they should ask questions, but really the balance is in favor of getting this vaccine.”

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Q: Why do you need multiple doses and how long does your immunity last?

The first dose immediately gives you most of the protection against severe disease — about 80% effectiveness, on average — and the second dose takes you all the way there. Plus experts think the second dose may extend how long the vaccine lasts.

Fourteen days after your first dose, you are around 92% protected. In case that makes you think about skipping the second dose, remember that the vaccine trials were two doses, so what we know about how well the vaccine works depends on two doses.

Researchers still don’t know exactly how long your immunity will last after receiving both doses. Only a few months of data on the vaccines exist so far. But, says Dr. Bibbins-Domingo, there are indications they will provide longer-term immunity.

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Q: Does an mRNA vaccine give me the virus?

No. An mRNA vaccine contains no live virus and no synthetic virus. It trains your immune system to make antibodies against the coronavirus and then disappears. You cannot get COVID-19 from the vaccine. Also, mRNA vaccines do not interact with your DNA because the mRNA does not enter the cell nucleus.

The antibodies your immune system creates protect you from the symptoms of COVID-19, especially severe symptoms. It’s important to keep in mind, however, that the time between getting the vaccine and producing these antibodies is several weeks.

Marla Broadfoot, a Ph.D. geneticist who’s also an independent journalist, likes to compare mRNA to scratch paper on which you write a note then throw away when you’re done.

“mRNA is a kind of molecular scratch paper that carries these instructions around the cell where they can be used to construct proteins,” she told the Association of Healthcare Journalists. “In the case of the COVID-19 vaccines, the mRNA is giving our cells instructions for making the spike protein, a harmless bit of the coronavirus. Our cells recognize the protein as foreign and make antibodies against it and against the virus. In the meantime, the mRNA scratch paper disintegrates.”

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Q: Do the vaccines work against the variants?

Yes. You may have heard otherwise, but the important point is that the vaccines are highly effective against the variants in preventing severe disease — that is, preventing hospitalizations and deaths. It’s true the vaccines were less potent against the variants in lab tests, meaning they generated fewer antibodies. However, the vaccines trigger a range of immune responses in addition to antibodies, and the immune response is so robust that it can lose a good bit of potency and still be effective.

Experts think a vaccinated person who contracts a variant of the coronavirus may experience mild or moderate symptoms a little more than they would with the original coronavirus.

It’s normal for viruses to mutate, and scientists expected it. The important point is that every infection the vaccines prevent denies the coronavirus a chance to mutate further.

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Q: Can you still get and transmit COVID-19 if you’ve been vaccinated?

The vaccines were tested on how effective they are at preventing severe disease. The studies did not examine whether the vaccines prevent infection or transmission of that infection. All indications are that they do, says Dr. Bibbins-Domingo, but this is still being studied. The uncertainty about this is why people who’ve had the vaccine are advised to continue to wear masks and socially distance.

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Q: Should you get vaccinated if you’re pregnant or breastfeeding?

The vaccines were not studied in pregnant and nursing women. Based on the review of the data on how the mRNA vaccines work and on the side effects, says Dr. Bibbins-Domingo, medical authorities say pregnant and nursing women should consider getting the vaccine.

Pregnant women are at higher risk than other women of having severe illness if they contract COVID-19, according to the CDC, and might be at higher risk of preterm birth or other complications.

The World Health Organization says women who are at high risk of exposure or who have underlying health conditions may receive the vaccine.

The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine say the vaccine should not be withheld from pregnant women who wish to receive it. Both organizations objected to excluding pregnant and lactating women from the vaccine trials, and they are pressing for future trials to include these groups.

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Q: Were the vaccines tested on racially and ethnically diverse populations? Were they effective for a range of races/ethnicities?

Yes. And yes.

The drug companies gathered demographic information from participants in the study. Both of the vaccine clinical trials included a smaller percentage of Blacks and Asians than in the U.S. population and a roughly similar percentage of Latinos. Here’s where you can find the demographic information for Moderna’s vaccine, and for Pfizer-BioNTech’s. And here’s the U.S. population from the census as of 2019.

The coronavirus has hit certain populations much harder: Black, Latino, Indigenous and lower-income people are suffering high rates of COVID-19 and are among the most important groups to be vaccinated. At the same time, says Dr. Bibbins-Domingo, they may have serious questions about the vaccines.

“Oftentimes these same communities have very legitimate concerns about trusting government, trusting the medical establishment, trusting science, because of historical instances where, really, there is basis for that mistrust,” said Dr. Bibbins-Domingo.”

The United States’ history of medical exploitation, especially of minorities, includes incidents like the widely condemned Tuskegee experiment on Black men with syphilis, from 1932-1972, and the forced sterilization of Latina, African American and Native American women as late as the 1970s.

While there are many examples of racist treatment throughout the history of health care, there are also failures in America’s current health care system that reinforce structures of racism and drive distrust. And the country’s immigration debate can also show why it’s hard for people of color to trust government health projects.

Dr. Bibbins-Domingo encourages people to seek answers to their questions, particularly from doctors or organizations they trust.

Bay area organizations such as Roots Community Health Center, Community Health for Asian Americans, The Latina Center, and the Native American Health Center serve their communities and understand the historical factors and current struggles that influence perceptions of the health care system.

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Q: What are the differences between the Moderna and the Pfizer-BioNTech vaccines? Is one better than the other?

The vaccines are essentially the same; they are both mRNA vaccines, with the same side effects and the same effectiveness. The way they prompt your immune system to respond and make antibodies is the same. The main difference is which fat globule they use to get the mRNA into the cell.

Both vaccines require two doses. For the Moderna vaccine, you need to wait 28 days between shots. For the Pfizer-BioNTech vaccine, you need to wait 21 days between. But you can wait up to six weeks if doses are in short supply.

The most important point is that everyone should get two doses, says Dr. Bibbins-Domingo; don’t skip the second one.

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Q: Are the vaccines safe for all ages?

Pfizer-BioNTech’s vaccine was tested and found safe for ages 16 and up. Moderna’s vaccine has been approved for ages 18 and up.

Drug companies have to test the vaccine in an age group before they can show it’s safe for those ages, and they didn’t test the vaccine in younger children. This research is happening now, and the results may be released in 3-5 months.

For people 65 and older, the risk from COVID-19 is much higher than the risk of the vaccine. Very elderly and frail people with underlying health conditions should be evaluated before receiving the vaccine.

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Q: Why should young people get vaccinated?

While young people are less likely to get really sick from COVID-19, they can still get and spread the virus. Also, many young people are in contact with parents, grandparents and others who are older and more at risk. Finally, while the likelihood of a young person getting a serious case requiring hospitalization is lower, some have become seriously ill or died.

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Q: Should I get vaccinated if I already had COVID-19? And how long should I wait after I’ve had COVID-19 to get it?

Yes. The level of protection you receive from the vaccine is higher than what you get from having had COVID-19.

According to the CDC, once you’ve recovered and completed your isolation requirements, you can get the vaccine. However, the CDC says people who were treated for COVID-19 with monoclonal antibodies or convalescent plasma should wait 90 days before getting the vaccine.

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Q: If I’m vaccinated, can I stop wearing a mask and get close to people again?

No. Even if you’re vaccinated, you can still get and transmit the disease. Remember, the trials only thoroughly tested how well the vaccine protects against the symptoms of COVID-19. Researchers need to study more to learn whether the vaccine prevents infection and transmission.

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Q: I am immunosuppressed; should I still get the vaccine?

Immunocompromised people are at a higher risk for severe COVID-19. While there is no data on mRNA vaccines in people who are immunocompromised, the CDC does not recommend against it, but does recommend people be counseled.

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Q: Do the COVID-19 vaccines cause infertility?

No. There’s no evidence that COVID-19 vaccines cause infertility. In early December, an internet post spread a false rumor about this, but it was proven to be untrue.

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Q: Does the vaccine allow any authority to track me?

No. There is a microchip on the syringe’s label (not inside the actual vaccine) that tracks the vaccine’s expiration date and whether it has been used. It does not track who receives the vaccine.

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Q: How do I get the vaccine?

See KQED’s “Where Can I Get a COVID-19 Vaccine in the Bay Area? ” post.

California’s MyTurn website will tell you if you’re eligible for the vaccine and when appointments are available. If you’re not eligible, you can register to receive a notification when you become eligible.

*If you are wondering whether you should get a vaccine, contact your health provider.

Copyright 2021 KQED