Vaccine Basics

Five Things to Know

1. Safety

The safety of COVID-19 vaccines is a top priority. No steps are skipped during the clinical trial process. Vaccine safety checks are in-progress and will continue.

2. mRNA Vaccines Work

mRNA vaccines will be some of the first COVID-19 vaccines authroized for use. mRNA vaccines do not use the live virus that causes COVID-19. They cannot give someone COVID-19.

3. Benefits

Getting vaccinated may help keep you from getting seriously ill and may also protect people around you. People who have gotten sick with COVID-19 may still benefit from getting vaccinated.

4. Number of Doses

The first COVID-19 vaccines will require two shots. The first shot starts building  protection, but everyone will have to receive the second shot to get the most protection the vaccine can offer.

5. Availability and Cost

Chicago receives a limited amount of a COVID-19 vaccine each week. CDPH is following federal and state guidelines for distribution. Review Chicago's vaccination plan for details. The vaccine will be offered at no cost to all Chicagoans who want it as soon as larger quantities become available.

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No steps are skipped during the clinical trial process for COVID-19 vaccine.

  • The FDA authorizes vaccines after they pass three phases of clinical trials
  • These clinical trials require thousands of people and months of data
  • The vaccine development is faster than normal because some steps are being done at the same time instead of one after another

Vaccine safety checks are in-progress and will continue as long as a vaccine is available.

  • When a vaccine trial is paused or cancelled, it is normal and means the safety checks are working
  • Vaccine recalls are rare. If a recall is issued, the FDA and CDC will let health officials and the media know immediately
  • After the vaccine is authorized, FDA and CDC will continue to monitor it using three federal safety systems that are already in place

Early studies have shown the vaccine is still effective against COVID-19 variants.

  • Evidence suggests that variants can spread more easily but there is no evidence that the new strain affects the sensitivity of diagnostic tests or that it causes more severe illness or increased risk of death

  • Data suggest current vaccines will be effective and safe in providing protection against the variant

Learn more at Centers for Disease Control and Prevention.

Benefits of Getting COVID-19 Vaccine

COVID-19 vaccination will help keep you from getting COVID-19

  • Getting a COVID-19 vaccine may help keep you from getting seriously ill even if you do get COVID-19.
  • Getting vaccinated yourself may also protect people around you, particularly people at increased risk for severe illness from COVID-19.

COVID-19 vaccination will be a safer way to help build protection

  • COVID-19 can have serious, life-threatening complications, and there is no way to know how COVID-19 will affect you. And if you get sick, you could spread the disease to friends, family, and others around you.
  • Getting COVID-19 may offer some natural protection, known as immunity. But experts don’t know how long this protection lasts.
  • The risk of severe illness and death from COVID-19 far outweighs any benefits of natural immunity. COVID-19 vaccination will help protect you by creating an antibody response without having to experience sickness.

COVID-19 vaccination will be an important tool to help stop the pandemic

  • Stopping a pandemic requires using all the tools we have available. Together, COVID-19 vaccination and everyday preventative actions will offer the best protection from COVID-19.
  • Wearing masks and social distancing help reduce your chance of being exposed to the virus or spreading it to others, but these measures are not enough. Vaccines will work with your immune system so it will be ready to fight the virus if you are exposed.

For more information, see Facts about COVID-19 vaccines.

mRNA Vaccines

The two vaccine candidates that have completed enrolling Phase III clinical studies in the United States were developed using a new vaccine technology employing messenger RNA (mRNA). When authorized or approved, these will be the first vaccines approved using mRNA technology.

  • mRNA vaccines are being held to the same rigorous safety and effectiveness standards as all other types of vaccines in the United States. The only COVID-19 vaccines the Food and Drug Administration (FDA) will make available for use in the United States (by approval or emergency use authorization) are those that meet these standards.
  • mRNA vaccines cannot give someone COVID-19. They do not use the live virus that causes COVID-19.
  • mRNA vaccines do not affect or interact with our DNA in any way. mRNA never enters the nucleus of the cell, which is where our genetic material (DNA) is kept. The cell breaks down and gets rid of the mRNA soon after it is finished using the instructions.

Learn more at Centers for Disease Control and Prevention.

Vaccine History

Vaccinations have saved hundreds of millions of lives over the last century. Scientists have developed vaccines for Smallpox, Polio, Measles, Mumps, Rubella, Hepatitis, Meningitis and more. The WHO considers vaccine development one of the greatest global health achievements.