Frequently asked questions about COVID-19 vaccine
Updated on April 28, 2021 at 3:15 p.m.
Updates: Removed information regarding outdated vaccine eligibility and vaccine supply from several questions.
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Section 1: COVID-19 vaccine development and safety
The Food and Drug Administration (FDA) has authorized the emergency use of the first COVID-19 vaccines. Multiple other vaccines are under development and several are in large scale clinical trials with tens of thousands of volunteers to ensure they are both safe and effective.
The Food and Drug Administration (FDA) uses Emergency Use Authorizations, known as EUAs, during national emergencies to make a product available to address an urgent health need. The EUA allows a product to be used before it has a full license.
An EUA can be used for tests, devices, or treatments. The FDA has issued EUAs to address anthrax, Ebola, H1N1 and other health emergencies in the past.
FDA guidelines must be met for a COVID-19 vaccine to be considered for an EUA, including safety and effectiveness standards and review by independent medical experts.
If the FDA approves a vaccine for an EUA, a second independent advisory committee will evaluate the safety and effectiveness data. This committee, the Advisory Committee on Immunization Practices (ACIP), will then make a recommendation about whether the vaccine should be used. If they recommend it, ACIP will issue guidelines for healthcare providers.
The FDA and CDC will continue to monitor a vaccine’s safety and effectiveness even after it is approved.
Vaccine safety is a priority. All COVID-19 vaccines must go through a rigorous and multi-step testing and evaluation process before they can be used in the U.S. These include studies with tens of thousands of people and data review by independent safety monitoring boards. They will only be approved or authorized for use if they pass safety and effectiveness standards. Vaccines will also be monitored for safety once they are given.
This short video from the CDC explains more about how COVID-19 vaccines are made:
Usually, vaccine testing and production are done in multiple, time-consuming, separate steps over several years. Because of the pandemic, the federal government provided special funding to vaccine researchers and manufacturers to allow development, testing and production to happen at the same time. No steps are skipped but the timeline for development can go faster.
Vaccines that have been authorized from Pfizer and Moderna are mRNA vaccines. mRNA vaccine technology has been studied and worked with for decades. Interest has grown in these vaccines because they can be developed in a laboratory using readily available materials. This means the process can be standardized and scaled up, making vaccine development faster than traditional methods of making vaccines.
The Johnson & Johnson vaccine is a viral vector vaccine, a technology first created in the 1970s. For decades, hundreds of scientific studies of viral vector vaccines have been done around the world. They have been used against other infectious diseases like Ebola, Zika, flu and HIV.
When a vaccine is authorized by EUA, volunteers who get the COVID-19 vaccine are monitored for a shorter time than with the traditional vaccine approval process. Testing for any COVID-19 vaccine involves thousands of volunteers, and at least half of the volunteers are followed for at least 2 months after their last vaccine dose (rather than the 6 or more months in a traditional process). However, by two months, most side effects from vaccines are expected to surface.
It is possible that rare side effects may only be seen when millions of people are vaccinated. For this reason, the safety of COVID-19 vaccines will continue to be monitored after they are given.
Yes. As of April 24, 2021, adults age 18 and older can get the Johnson & Johnson COVID-19 vaccine after the CDC and FDA completed a thorough safety review of the vaccine.
Use of the Johnson & Johnson (also known as the J&J/Janssen) vaccine had been paused on April 13 as the CDC reviewed a small number of reports of a very rare condition involving blood clots and low platelet counts, mostly found in women ages 18 to 49. After a thorough review of the data, the CDC determined that the risk of this condition is extremely low. By contrast, the J&J vaccine provides protection from the much higher risk of hospitalization and death from COVID-19.
Women younger than 50 years old should be aware of the risk of this very rare but serious reaction. Other COVID-19 vaccines (Pfizer and Moderna) are available that do not have this risk.
If you get the J&J vaccine, watch for these symptoms for three weeks after vaccination:
- severe or persistent headache or blurred vision
- chest pain
- shortness of breath
- leg swelling
- persistent abdominal pain
- easy bruising or tiny blood spots under the skin
Seek medical care right away if you develop one or more of these symptoms.
Note: If you got the vaccine more than a month ago, your risk is very low. It is normal to have mild to moderate symptoms, including fever, headache, fatigue, and joint/muscle pain during the first week after receiving any COVID-19 vaccine.
If you have any questions or concerns, call your doctor, nurse, or clinic. The CDC and FDA will continue to monitor the safety of all COVID-19 vaccines, and Public Health will provide updates as additional information becomes available.
This video from the WA Department of Health offers advice to consider the tone, author, and sources when you see new information, and to check with people you know. Public Health has also developed a resource called Is it True? to discuss some common misinformation about COVID-19 vaccine.
Section 2: How COVID-19 vaccine works
COVID-19 vaccines help our bodies develop immunity to the virus that causes COVID-19 without us having to get the illness. When you get the vaccine, your immune system makes antibodies and other infection-fighting cells that protect you in case you are infected with the virus.
Watch a short video from the WA State Dept. of Health that explains more about how COVID-19 vaccines work in your body:
COVID-19 vaccination will help you from getting sick or seriously ill with COVID-19.
- It helps protect you by teaching your body’s immune system to fight the virus without having to experience a COVID-19 infection.
- In the clinical trials, the COVID-19 vaccines that are currently available were found to be highly effective in protecting people from COVID-19.
COVID-19 vaccine will be an important tool to help stop the pandemic.
- Getting vaccinated will help to protect you, your friends and family, and other people in the community from COVID-19. The combination of getting vaccinated and following public health recommendations will offer the best protection from COVID-19 at this time.
- Wearing masks and social distancing help reduce your chance of being exposed to the virus or spreading it to others, but these measures alone are not enough. Vaccines will work with your immune system so it will be ready to fight the virus if you are exposed.
- Over time, as more people are vaccinated, we may no longer need some of the other COVID-19 prevention measures that are necessary at this time.
No, COVID-19 vaccines cannot cause COVID-19 infection. COVID-19 vaccines teach our bodies to protect us by making antibodies and other infection-fighting cells, In the case of mRNA vaccines (like the Pfizer and Moderna vaccines), they protect by instructing our own cells to produce a protein that can teach the immune system to prevent COVID-19 illness without using any part of the COVID-19 virus at all.
It’s possible to get side effects like headache, a sore arm, fatigue or a fever in the day or two after you get the shot. But these side effects are short-lived and are signs that the vaccine is building immunity in the body. Some of these side effects may be similar to the symptoms of COVID-19, but it is not the same as an infection. The vaccine does not contain a virus or any part of a virus and cannot cause COVID-19.
Vaccines that have been authorized from Pfizer and Moderna are mRNA vaccines. mRNA vaccine technology has been studied and worked with for decades.
There is no virus in the mRNA vaccines, so you cannot get a COVID-19 infection from the vaccine. Instead, mRNA vaccines give our cells instructions to make a harmless protein—one that looks just like an important protein on the COVID-19 virus. When your cells make that protein, your body creates a strong immune response and antibodies to protect against COVID-19. Your body learns how to protect you from getting infected without exposure to the virus.
After the mRNA teaches our cells to protect against COVID-19, our body’s enzymes quickly break down and eliminate the mRNA. mRNA does not get into the nucleus of our cells, DNA, or genetic material.
Although these are the first mRNA vaccines to be authorized for use, mRNA technology has been studied for more than 30 years. More information about how mRNA vaccines work can be found on the CDC’s website.
Yes, make sure to get your second dose of the Moderna or Pfizer vaccine series. Without the second dose, you are not considered fully vaccinated.
We’ve heard that some people are considering skipping the second dose because they are worried about possible side effects. However, the second dose is important to give you the full protection- the first dose starts building immunity, and the second dose strengthens it.
Not everyone has side effects from the second dose, and some people have milder side effects than others. If you do have side effects, they will likely last no more than a few days. These are all signs that the vaccine is working and your body is building up immunity.
The Johnson & Johnson COVID-19 vaccine uses a harmless form of the common cold virus (not the coronavirus) that’s been modified so that it can’t make you sick. This harmless virus delivers instructions to teach our cells to make a protein found on the surface of the coronavirus. When your cells make that protein, your body creates a strong immune response to protect against COVID-19. Your body learns how to protect you from getting infected with COVID-19 without exposure to the actual coronavirus.
This type of vaccine cannot infect you with COVID-19 or with the harmless common cold virus used to deliver the instructions. The vaccine does not get into or change the nucleus of our cells, DNA, or genetic material.
Scientists began creating viral vectors in the 1970s. For decades, hundreds of scientific studies of viral vector vaccines have been done around the world. They have been used against other infectious diseases like Ebola, Zika, flu and HIV.
Women younger than 50 years old should be aware of the risk of a very rare but serious condition involving blood clots and low platelet counts. Other COVID-19 vaccines (Pfizer and Moderna) are available that do not have this risk. Please see the question “Is the Johnson & Johnson vaccine available?” in Section 1 for more information.
The key ingredient in both the Pfizer and Moderna vaccines is mRNA, which tells your cells how to make a protein from the coronavirus, allowing it to recognize COVID-19 and protect you from infection. The vaccines also contain lipids, salts, and sugar.
The key ingredient in the Johnson & Johnson vaccine is adenovirus 26, a harmless virus used to deliver the spike protein that’s on the surface of the coronavirus to our cells. The cells can then recognize COVID-19 and protect you from infection. The Johnson & Johnson vaccine also contains citric acid and ethanol.
The vaccines do not contain: pork products, egg, latex, blood products, COVID-19 virus cells, mercury, or microchips. The vaccines do not contain fetal tissue.
Full list of ingredients in the Pfizer vaccine, available from the FDA:
- nucleoside-modified messenger RNA (modRNA) encoding the viral spike glycoprotein (S) of SARS-CoV-2
- (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2- hexyldecanoate)
- 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide
Additional ingredients (salts, sugars, buffers)
- potassium chloride
- monobasic potassium phosphate
- sodium chloride
- dibasic sodium phosphate dihydrate
Full list of ingredients in the Moderna vaccine, available from the FDA:
- nucleoside-modified messenger RNA (modRNA) encoding the viral spike glycoprotein (S) of SARS-CoV-2
- polyethylene glycol (PEG) 2000 dimyristoyl glycerol (DMG)
Additional ingredients (salts, sugars, buffers)
- tromethamine hydrochloride
- acetic acid
- sodium acetate
Full list of ingredients in the Johnson & Johnson (Janssen) vaccine, available from the FDA:
- recombinant, replication-incompetent adenovirus type 26 expressing the SARS-CoV-2 spike protein
- citric acid monohydrate
- trisodium citrate dihydrate
- 2-hydroxypropyl-β-cyclodextrin (HBCD)
- sodium chloride
The Moderna and Pfizer vaccines continue to offer a high level of protection against COVID-19 and remain essential to stop COVID-19 from spreading. The Centers for Disease Control and Prevention (CDC) reports that the Moderna and Pfizer vaccines appear to be effective against the B.1.1.7 variant, also known as the UK variant, which has been found in Washington state. Studies suggest that antibodies produced by the vaccines also recognize the B.1.351 (South Africa) and P.1 (Brazil) variants. Health experts continue to monitor and research how effective the vaccines will be against variants.
The Johnson & Johnson vaccine clinical trial was completed more recently, while newer more contagious variants were circulating widely, and is found to be highly effective. The Johnson & Johnson vaccine offers a high level of protection against severe illness, hospitalization and death from COVID-19, the B.1.351 (South Africa) and P.1 (Brazil) variants. Health experts continue to monitor and research how effective the vaccine will be against variants.
We will prevent the virus from circulating and reduce additional variants by getting vaccinated and continuing to practice other COVID-19 prevention measures including wearing masks, physical distancing from people outside our homes, and washing hands.
Section 3: Vaccine availability
While COVID-19 vaccines are in short supply, eligibility phases have included high-risk groups determined by the Washington State Department of Health. As Washington State’s vaccine distribution plan moves forward, anyone eligible for vaccine in earlier phases of the plan continues to be eligible.
- Learn more about vaccine eligibility. On April 15, 2021, all adults ages 16 and older will be eligible for the vaccine. Please wait until you are eligible to schedule your vaccine appointment.
- Learn more about Washington State’s COVID-19 vaccine distribution here.
COVID-19 vaccines are being distributed to hospitals, pharmacies, high-volume sites, community health centers and other providers. Learn more about where to get vaccinated in King County.
Some vaccine providers list the type of vaccine available on their online registration sites or can provide that information over the phone. All of the vaccines authorized for use will prevent hospitalization and death from COVID-19. All of the vaccines are safe and highly effective. However, some important differences are:
- Age eligibility: the Pfizer vaccine can currently be given to people 16 and older. The Moderna and Johnson & Johnson vaccines can be given to people 18 and older.
- The number of doses: the Johnson & Johnson vaccine only requires one dose. Two doses are necessary for the Pfizer vaccine (at least 3 weeks apart) and Moderna vaccine (at least 4 weeks apart).
Different provider sites may have different vaccines as they become available. Vaccine supply can change, so the type of vaccine that a provider gets may also change.
Vaccine clinical trials for children are currently in early stages and COVID-19 vaccines will not be available until study data shows that the vaccines are safe and effective for children as well as adults. The Pfizer vaccine has been authorized for ages 16 and older and the Moderna and Johnson & Johnson vaccines have been authorized for ages 18 and older.
Getting vaccinated is a personal choice. Any of the currently authorized COVID-19 vaccines can be offered to people who are pregnant or breastfeeding. If you have questions about getting vaccinated, a conversation with your healthcare provider might help, but is not required.
Section 4: What to expect
There is no cost to you for the COVID-19 vaccine, regardless of immigration or health insurance status. The vaccine will be covered by Medicare, Medicaid and most private insurance, and the cost of the vaccine will be covered for people who are uninsured.
COVID-19 vaccination providers cannot:
- Charge you for the vaccine.
- Charge you directly for any administration fees, copays, or coinsurance.
- Deny vaccination to anyone who does not have health insurance coverage, is underinsured, or is out of network.
- Charge an office visit or other fee to the recipient if the only service provided is a COVID-19 vaccination.
- Require additional services in order for a person to receive a COVID-19 vaccine; however, additional healthcare services can be provided at the same time and billed as appropriate.
COVID-19 vaccination providers can:
- Seek appropriate reimbursement from the recipient’s plan or program (example: private health insurance, Medicare, Medicaid) for a vaccine administration fee. However, providers cannot charge the vaccine recipient the balance of the bill.
- Seek reimbursement for uninsured vaccine recipients from the Health Resources and Services Administration’s COVID-19 Uninsured Program.
Public Health – Seattle & King County and others are offering free vaccination clinics. Equitable distribution is a priority for these clinics. More information can be found on our Getting Vaccinated in King County page.
It depends on which vaccine you get. The Johnson & Johnson COVID-19 vaccine only requires one dose for complete protection. The Pfizer and Moderna vaccines require two doses, one shot to start building protection and a second shot to maximize and complete the protection.
Your second shot should be given 21 or 28 days after the first one, depending on the type of vaccine. You will need to get the same type of vaccine for both shots. When you get your first shot, your vaccination provider will give you information if you need a second dose and when to get it.
The recommended schedule for getting your second dose is 21 days after the first dose for the Pfizer vaccine and 28 days after the first dose for the Moderna vaccine. It’s best to receive the second dose as close to that timeline as possible, but you may receive the second dose up to 6 weeks (42 days) after the first dose. It’s not yet known how effective mRNA COVID-19 vaccines are when the second dose is received more than 42 days after the first dose. However, you may still receive your second dose after 42 days, and do not need to restart the vaccine series.
Some people might have some symptoms like headache, a sore arm, fatigue, fever, or muscle aches for a few days after getting the shot. These symptoms are more common after the second dose of vaccine. These are all signs that the body’s immune system is building up protection. This is normal and can also be seen after other commonly used vaccines.
Anaphylaxis—a severe allergic reaction—is extremely rare after getting the COVID-19 vaccine. Everyone who experienced anaphylaxis after COVID-19 vaccination has fully recovered, based on available information, and no deaths have occurred. The risk of severe illness and death from COVID-19 is far greater than the risk of experiencing anaphylaxis or another severe reaction after vaccination.
The CDC has published reports with additional information on anaphylaxis and other allergic reactions to the vaccines:
- Allergic reactions, including anaphylaxis to the Moderna COVID-19 vaccine
- Allergic reactions, including anaphylaxis to the Pfizer COVID-19 vaccine
The CDC will release a similar report for the Johnson & Johnson vaccine soon. In clinical trials, anaphylaxis was extremely rare after getting the Johnson & Johnson vaccine.
Most people who experienced anaphylaxis developed symptoms within 15 minutes of getting the vaccine. All these patients were treated with epinephrine immediately after showing symptoms.
All vaccination locations have medical professionals trained to identify and respond to anaphylaxis. They monitor everyone who receives a COVID-19 vaccine for 15 minutes following the vaccination so they can assist if needed.
You may return to work and not quarantine within a few days of vaccine administration, IF:
- You have not been in contact with someone with COVID-19 AND
- You feel well enough and are willing to perform normal activities such as work AND
- You do not have a fever AND
- Signs and symptoms are limited only to those observed following COVID-19 vaccination (see list of symptoms, including pain, swelling, tiredness, chills, headache) AND
- You do not have other signs and symptoms of COVID-19, such as cough, shortness of breath, sore throat, or change in smell or taste.
CDC: Post Vaccine Considerations for Healthcare Personnel
CDC: Post Vaccine Considerations for Residents of Long-Term Care
The CDC has created V-safe, a free, smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins after you receive a COVID-19 vaccination. V-safe also reminds you to get your second dose. We encourage you to participate in V-safe. Learn more at www.cdc.gov/vsafe.
Yes. You are not fully protected until 2 weeks after the second dose in a 2-dose vaccine series (like Moderna or Pfizer) or 2 weeks after a single-dose vaccine (like J&J). We’re also learning how well the vaccine works in preventing people who are vaccinated from spreading COVID-19 to others and how well it works on coronavirus variants, which are known to be circulating in King County.
Even after vaccination, it’s important to protect others. Continue to wear masks, limit indoor activities outside of the home, avoid crowded indoor spaces, keep contact with others brief and distanced, improve ventilation indoors, and wash your hands frequently.The good news is that once you’re fully vaccinated, you can start doing some things again that stopped because of the pandemic. Learn more on the Getting Vaccinated in King County page.
COVID-19 vaccines will not cause you to test positive on viral tests used to detect current infection.
Antibody tests look for antibodies in the blood that indicate if a person has been infected with a virus or bacteria. Antibodies are also produced when someone receives an effective vaccine. If your body develops an immune response to the COVID-19 vaccine, it is possible that you may test positive on some antibody tests for COVID-19.
Yes, you should be vaccinated regardless of whether you already had COVID-19. Experts do not yet know how long you are protected from getting sick again after recovering from COVID-19. Even if you have already recovered from COVID-19, it is possible that you could be infected with the virus that causes COVID-19 again.
You should wait three weeks after testing positive for COVID-19 to get a vaccine. If you were treated for COVID-19 with monoclonal antibodies or convalescent plasma, you should wait 90 days before getting a COVID-19 vaccine. Talk to your doctor if you are unsure what treatments you received or if you have more questions about getting a COVID-19 vaccine.
It will be your choice whether to get the vaccine for COVID-19. Washington State is not currently considering any mandates for the vaccine, but employers could require it. Public Health recommends COVID-19 vaccination as is a safe, effective, and important way to prevent COVID-19, decrease illnesses, hospitalizations, and deaths due to COVID-19, and help to stop the current pandemic.
Currently, the U.S. government is not requiring COVID-19 vaccination for visitors to the United States, or for U.S. residents traveling to other countries when they reenter the U.S. However, individual airlines may require travelers to provide proof of vaccination when flying on their airline. Please check all travel safety requirements with your airline before arranging travel.
As vaccine distribution continues, other countries may require proof of vaccination in the future before allowing travelers to enter, but no countries have established vaccination requirements at this time.
Safe and effective vaccines against COVID-19 are a major breakthrough in preventing COVID-19 and eventually ending the COVID-19 pandemic. But vaccines alone won’t end the pandemic right away. At this time, vaccination needs to be used in combination with other prevention methods.
Even after a vaccine is available, stopping the pandemic will continue to require everyone – even if vaccinated – to continue to follow current guidance to protect themselves and others. For several months, we will need to continue wearing a mask, staying at least 6 feet away from others, limiting activities outside the home and avoiding crowds, washing hands often, following CDC travel guidance, and following quarantine guidance after an exposure to someone with COVID-19.