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1. Are the available COVID-19 vaccines safe and effective?

Yes, the vaccines were tested on tens of thousands of people and have passed safety requirements in Phase I, Phase II and Phase III trials. Over 179 million people have gotten vaccinated in the United States so far.

For more safety information, visit the trustworthy sources below for in-depth and accurate information about vaccine safety and effectiveness.

• COVID Vaccine Facts (Missouri Dept. of Health & Senior Services)
• Ensuring the Safety of COVID-19 Vaccines in the United States (CDC)
• Ensuring COVID-19 Vaccines Work (CDC)
• COVID-19 Vaccines (FDA)
• Safety of Vaccines for Kids (MO DHSS)

2. Is it safe to get my child vaccinated?

Yes. Scientists and medical experts have worked to ensure the vaccine is safe for children and adolescents ages 6 months to 17 years old. Before being authorized for children, these experts completed their review of safety and effectiveness data from clinical trials involving thousands of children. What’s more, 22 million children and adolescents, ages 5-17 have already received the COVID-19 vaccine. As of June 18, 2022, the Pfizer and Moderna vaccines are also authorized for children as young as 6 months.

Data from trials will continue to be collected for two years after each vaccine is first administered to ensure that they are safe for the long term. As with all vaccines, there will be ongoing monitoring among people who are vaccinated.

Learn more about COVID-19 vaccines for children and teens. 

3. Why did it take so long for the FDA to make a decision about vaccines for children under 5?

All the COVID-19 vaccines have undergone a rigorous review process before being authorized for a given age group. The FDA’s evaluation of vaccines for young kids has been part of this overall thorough review process. Clinical trials were not started in children until after the trials in adults showed safety and efficacy of the vaccines. 

Additionally, part of what made the review process longer for young kids is that experts were determining what dosage and series would be safe and effective for children under five. After reviewing initial data on the effectiveness of the vaccine in young kids, the FDA waited to receive additional findings from clinical trials to ensure that its recommendation was based on a substantial amount of clinical data.  

4. Is it safe to get vaccinated if I am pregnant or breastfeeding?

Yes. COVID-19 vaccination is recommended for all people 6 months and older, including people who are pregnant, breastfeeding, trying to get pregnant now, or might become pregnant in the future.

Evidence about the safety and effectiveness of COVID-19 vaccination during pregnancy has been growing. These data suggest that the benefits of receiving a COVID-19 vaccine outweigh any known or potential risks of vaccination during pregnancy.

Please visit CDC's COVID-19 Vaccines While Pregnant or Breastfeeding for updated information to help you make your decision. You can also hear from medical professionals here.

5. How was the vaccine developed so quickly?

• In developing a vaccine for COVID-19, researchers had to work quickly, but not at the risk of anyone’s safety. Researchers did not cut any corners or skip any steps. Safety and effectiveness were the top priorities. 
• The accelerated timeline for developing COVID-19 vaccines was possible for several reasons: 
  • Researchers were able to use years of previous research in other viruses and vaccines to help inform a vaccine development process for COVID-19. 
  • Everyone involved dedicated all their resources and time to developing a COVID-19 vaccine. This includes research institutions, pharmaceutical companies, government agencies, and philanthropic organizations. 
  • Many governments around the world, including the U.S. government, and private funders invested in the vaccine, which allowed pharmaceutical companies to focus on research and clinical trials instead of fundraising, one of the most time-consuming parts of vaccine development. 
  • Finally, because of the financial support, researchers were able to conduct different parts of the development process on parallel tracks instead of one after another. Usually, each phase in a clinical trial ends before the next phase begins, with several months to a year or more in between each phase. Vaccine developers use this time to plan and raise money. Because of the emergency presented by the pandemic, researchers developed the vaccines on parallel tracks, meaning that they completed the necessary steps at the same time or with some overlap. No steps were skipped in the process of developing the COVID-19 vaccines.

6. What ingredients are used in the vaccines?

The ingredients used in the mRNA vaccines developed by Pfizer and Moderna are simple. They contain mRNA, as well as lipids to ensure safe delivery of the mRNA that will initiate an immune response.

Ingredients of the Janssen COVID-19 vaccine include: recombinant, replication-incompetent adenovirus type 26 expressing the SARS-CoV-2 spike protein, citric acid monohydrate, trisodium citrate dihydrate, ethanol, 2-hydroxypropyl-β-cyclodextrin (HBCD), polysorbate-80, sodium chloride.

Although FDA approved adjuvants (aluminum salts) and preservatives (ethlymercury) have a history of safe use in vaccines, they were not used by Pfizer, Moderna or Janssen.

• Tromethamine in the vaccine for children ages 6 months - 11 years: Tromethamine (Tris) buffer replaced phosphate buffered saline (pbs) in both the vaccine authorized for children 6 months - 11 years and an additional formulation authorized for those 12 and older. The Tris buffer in the vaccine for those 6 months - 11 years, which is a very small amount at 0.15 mg, is an inactive ingredient and serves as a stabilizer used to aide in a simpler and longer storage period. This switch will allow for the Pfizer vaccine to be stored at normal refrigeration temperatures for up to 10 weeks, which may increase the vaccine’s availability to underserved areas. Contrary to claims on social media, it is not being used to reduce blood acid levels in patients. Tromethamine has been used safely as an ingredient in FDA approved vaccines, like Ebola Zaire, smallpox and dengue fever, as well as the FDA approved Moderna COVID-19 vaccine.

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7. What are the possible side effects of a COVID-19 vaccine?

Among vaccine recipients during the Pfizer clinical trials, 8.8% reported experiencing any reaction they considered to interfere with daily activity; the most common symptoms were fatigue (4.2%), headache (2.4%), muscle pain (1.8%), chills (1.7%), and injection site pain (1.4%). Of note, more people experienced these side effects after the second dose than after the first dose.

Among vaccine recipients during the Moderna clinical trials, 9.1% reported local injection site reaction and 16.5% reported side effects with the most common being including fever, headache, fatigue, and muscle aches and pains.

Additionally, no specific safety concerns were identified for the Pfizer and Moderna vaccines in subgroup analyses by age, race, ethnicity, underlying medical conditions, or previous SARS-CoV-2 infection.

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8. Who is NOT recommended for each vaccine?

The Pfizer and Moderna vaccines are authorized for those age 6 months and older. The Johnson & Johnson vaccine is authorized for those 18 and older.

The vaccines are not recommended for individuals who have experienced a serious reaction (e.g., anaphylaxis) to a prior dose of a COVID-19 vaccine or to any of its components. For information on vaccine components, refer to the manufacturers’ package inserts from Pfizer, Moderna and Johnson & Johnson.

9. Can I get COVID-19 from the vaccine?

No. None of the authorized and recommended COVID-19 vaccines or COVID-19 vaccines currently in development in the United States contain the live virus that causes COVID-19. This means that a COVID-19 vaccine cannot make you sick with COVID-19.

10. Is Johnson & Johnson’s Janssen COVID-19 vaccine safe?

Yes. Although use of the J&J vaccine was temporarily paused in April 2021, following a thorough safety review, U.S health officials determined that the recommended pause should be lifted and use of the vaccine should resume.

The two agencies have determined the following:

• Use of the Janssen COVID-19 Vaccine should be resumed in the United States.
• The FDA and CDC have confidence that this vaccine is safe and effective in preventing COVID-19.
• The FDA has determined that the available data show that the vaccine’s known and potential benefits outweigh its known and potential risks in individuals 18 years of age and older.
• At this time, the available data suggest that the chance of TTS occurring is very low, but the FDA and CDC will remain vigilant in continuing to investigate this risk.
• Health care providers administering the vaccine and vaccine recipients or caregivers should review the Janssen COVID-19 Vaccine Fact Sheet for Healthcare Providers Administering Vaccine (Vaccination Providers) and Fact Sheet for Recipients and Caregivers, which have been revised to include information about the risk of this syndrome, which has occurred in a very small number of people who have received the Janssen COVID-19 Vaccine.

CDC’s independent Advisory Committee on Immunization Practices met to discuss the latest data on TTS, hearing from the vaccine manufacturer Janssen and the COVID-19 Vaccine Safety Technical (VaST) Subgroup, as well as a risk benefit analysis. ACIP is committed to be vigilant and responsive to additional information that could impact the risk benefit analysis of any of these vaccines. Vaccine safety monitoring will continue and any new information about TTS will be brought to ACIP as needed.

Update December 16, 2021

The Missouri Department of Health and Senior Services updated the standing orders for the Janssen COVID-19 vaccine to indicate that either authorized mRNA COVID-19 vaccines (Pfizer or Moderna) are preferred over the Janssen COVID-19 vaccine for the prevention of COVID-19 in individuals ages 18 years and older due to the risk of thrombosis with thrombocytopenia or Guillain-Barre (GBS) following vaccination. Clients medically unable to receive the mRNA COVID-19 vaccine or would otherwise not be vaccinated against COVID-19 may request the Janssen vaccine, and a CCPHC nurse may determine if the client is eligible for the vaccine.

11. Does the Johnson & Johnson/Janssen vaccine require special precautions?

Yes, those who have or have a history of thrombocytopenia, who have or have a history of a low platelet count, prior surgery (cardiac, orthopedic, trauma), cardiovascular disease, oral contraceptive use or hereditary thrombophilia. 

If you experience any of the following symptoms seek medical attention right away: Shortness of breath, chest pain, leg pain or swelling, backache, persistent abdominal pain, severe and persistent headaches, visual changes or easy bruising or tiny blood spots under the skin beyond the site of the injection.

Update December 16, 2021

The Missouri Department of Health and Senior Services updated the standing orders for the Janssen COVID-19 vaccine to indicate that either authorized mRNA COVID-19 vaccines (Pfizer or Moderna) are preferred over the Janssen COVID-19 vaccine for the prevention of COVID-19 in individuals ages 18 years and older due to the risk of thrombosis with thrombocytopenia or Guillain-Barre (GBS) following vaccination. Clients medically unable to receive the mRNA COVID-19 vaccine or who would otherwise not be vaccinated against COVID-19 may request the Janssen vaccine, and a CCPHC nurse may determine if the client is eligible for the vaccine.