Vaccines protect people from specific diseases by training the immune system to recognize and attack a virus before it can make them sick.

Vaccines also protect the community. When most of a population is immune to an infectious disease, people who are not immune are also protected because it is harder for the disease to spread. This also makes it harder for the virus to mutate.

Diseases that were once common in the U.S. – like measles, mumps and polio – are now very rare because most Americans have immunity through vaccines.

Vaccines must go through many tests and approval processes to make sure they are effective and safe before they are distributed to the public.

Vaccines usually go through six stages of development. During these stages, the vaccines being studied are called “candidates.”

1. Exploratory Stage
2. Pre-Clinical Stage
3. Clinical Trials – Phase 1, Phase 2, Phase 3
4. Manufacturing
5. Regulatory Review and Approval
6. Quality Control

To speed up the process for COVID-19 vaccines, some of these stages are happening at the same time. For example, drug companies may begin making a vaccine while it is still in Phase 3 clinical trials so that the vaccine is ready to distribute immediately if it is approved.

There are multiple international groups developing a vaccine.

In the U.S., the CDC, FDA, Department of the Defense (DoD), the National Institutes of Health (NIH) and others are collaborating to produce and distribute the a vaccine in an effort called Operation Warp Speed.

Companies working to develop vaccines include AstraZeneca, Eli Lilly and Company, Janssen (Johnson & Johnson), Moderna, Pfizer, BioNTech, and Cytiva.

In December 2020, the FDA gave emergency use approval to the first COVID-19 vaccines, created by Pfizer-BioNTech and Moderna. Emergency use approval was given to the Johnson & Johnson vaccine in February. Source 1, Source 2, Source 3, Source 4

The FDA issued Emergency Use Authorization (EUA) for the Pfizer/BioNTech and Moderna COVID-19 vaccines. The FDA determined that the vaccines may be effective in preventing COVID-19 and the known and potential benefits outweigh the known and potential risks.

Emergency Use Authorization (EUA) is an authority granted to the FDA which can be utilized when there is a public health emergency to facilitate the availability and use of medical solutions, including vaccines. The FDA may allow the use of unapproved medical products, or unapproved uses of approved medical products in an emergency to diagnose, treat or prevent serious life-threatening diseases or conditions.

Before approval, the COVID-19 vaccine was rigorously tested through a series of clinical trials to generate the data and other information needed by the FDA to determine safety and effectiveness. The clinical trials were conducted according to the rigorous standards set by the FDA.

Missouri is now in Phase 3 and all residents can get a free COVID vaccine.

All Missourians over age 16 can get a free COVID vaccine. There are multiple options for where you can get vaccinated, including local public health departments, hospitals, mass vaccination events, and pharmacies. Find a vaccine.

There are multiple agencies responsible for making sure new vaccines are safe. Before a vaccine becomes available, it must go through several rounds of tests with human volunteers. The FDA reviews the results of these studies before authorizing vaccines. The FDA also inspects the factories where vaccines are produced to ensure quality and safety.

Once a vaccine is released, agencies in the national vaccine monitoring system continue to oversee the safety of vaccines. These agencies monitor the safety of hundreds of millions of vaccines every year and include:

• Vaccine Adverse Events Reporting System (VAERS)
• The Vaccine Safety Datalink (VSD)
• Post-licensure Rapid Immunization Safety Monitoring System (PRISM)
• Clinical Immunization Safety Assessment Project (CISA)
• The Department of Defense (DoD)
• U.S. Department of Veterans Affairs (VA)
• National Institutes of Health (NIH)
• Office of Infectious Disease and HIV/AIDS Policy (OIDP)

Source 1, Source 2

The COVID-19 vaccines are available and recommended for older adolescents and adults. The Pfizer vaccine is authorized for people 16 and older. The Moderna and Johnson & Johnson vaccine are authorized for people 18 and older. Research on COVID vaccines for younger adolescents is ongoing and vaccines could be authorized for this age group later in 2021. Source 1, Source 2, Source 3

The Pfizer and Moderna vaccines both require two shots for full protection. Like other vaccines, there may be a need for “booster” shots in the future if immunity decreases. The Johnson & Johnson vaccine requires a single dose for full protection. Source 1, Source 2

Side effects are a normal part of vaccination. After getting a vaccine, the body launches an immune response that can produce short-term symptoms. These symptoms are a positive sign that the body is building immunity. During clinical trials for COVID-19 vaccines, some participants reported side effects including exhaustion or tiredness, muscle pain, chills, and fever. These symptoms were more common after the second dose of the vaccine and usually last for one or two days. These side effects do not mean that you are sick with COVID-19.

The potential side effects of a vaccine are much less serious than the long-term, life-threatening symptoms of COVID-19. Talk with your healthcare provider about any worries you may have about the vaccine and how you will handle potential side effects. Source 1, Source 2, Source 3, Source 4

In clinical trials, vaccine researchers are studying how well vaccines protect volunteers from getting sick with COVID-19. Researchers give the vaccine to some volunteers and give other volunteers a “placebo,” or a shot that contains no medicine. Researchers then compare how many volunteers in each group became sick with COVID-19. This is called “efficacy” or “effectiveness.”

In Phase 3 clinical trials, the efficacy was 94.5% for the Moderna vaccine, 95% for the Pfizer-BioNTech vaccine, and 85% for the Johnson & Johnson vaccine. All of the vaccines offer excellent protection against severe illness, hospitalization, and death from COVID.

Researchers are continuing to study how well the vaccine works in the real world and in specific groups of people. Source 1, Source 2

The Johnson & Johnson clinical trials showed the vaccine protected against several emerging variants. The Pfizer vaccine was tested before the variants were common, but new research suggests that the Pfizer’s COVID-19 vaccine will protect against the new strains of coronavirus found in the U.K. and South Africa. The preliminary study did not look at the Moderna vaccine, but similar testing will soon be done. Source

COVID-19 is a relatively new virus in humans. We don’t know yet know long immunity from infection or vaccination will last. Some people have been infected with COVID-19 more than once, which shows that immunity from natural infection may not last very long. Immunity from the vaccine is expected to last longer, but researchers will need to continue studying this question. Source 1, Source 2

Vaccines are an important tool in ending the pandemic and allowing vaccinated individuals safely return to normal activities. While many have received the vaccine, it will take several months to achieve herd immunity and stop the spread of the virus. In the meantime, we need to continue taking safety steps like frequent handwashing, wearing face masks, and physical distancing to prevent to protect ourselves and others. Source 1, Source 2

Technically, yes. States have the legal and constitutional power to introduce a vaccine mandate requiring people who live in the state to be vaccinated. Upon full approval from the FDA, states could make the COVID-19 vaccine a requirement before returning or accessing workplaces, schools and colleges. As of April 2021, no states had announced plans to mandate the vaccine. Missouri Governor Mike Parson has said he will not require vaccinations in Missouri. Source 1, Source 2

Yes. According to the U.S. Equal Employment Opportunity Commission (EEOC), workplaces can require that employees get the COVID-19 vaccine. However, if an employee chooses not to be vaccinated due to a disability or religious reasons, they cannot be fired, and the employer must make accommodations such as allowing the employee to work from home. The EEOC states that vaccination is not considered a “medical examination,” which employers cannot mandate.

In April 2021, the CDC and FDA recommended a pause in the use of the Johnson & Johnson vaccine after six reported cases of a rare type of blood clot called “cerebral venous sinus thrombosis” (CVST).

Out of an abundance of caution, distribution of the vaccine stopped while experts reviewed the safety of the vaccine. After their review, the FDA and CDC determined that the vaccine is safe and that the benefits of the vaccine outweigh the potential risks. They also educated doctors on how to identify and treat this rare side effect.

Health experts advise people who have received the Johnson & Johnson vaccine to not be overly worried but to watch for possible warning signs including severe headache, abdominal pain, leg pain and shortness of breath. If you experience any of these symptoms, contact your health provider.

Source 1, Source 2

The Pfizer-BioNTech vaccine is approved for those 12 and older, and the Moderna and AstraZeneca vaccines are authorized for those 18 and older. Trials for children under the age of 12 are still underway and vaccines for this age group may be authorized later in 2021.

There is a lot of new information – and sometimes untrue information – about the vaccines, and it can be hard to know who to turn to for advice.

It is best to talk with a healthcare professional, like your doctor, who has the scientific knowledge to answer your questions and who has your family’s best interests in mind. Download a discussion guide to help with this conversation here.

Other sources of reliable information about the vaccines include your local public health department, the CDC, the FDA, and professional associations like the American Academy of Pediatrics.