Vaccine FAQ

For the CDC's FAQ sheet regarding vaccines please, click here

For the John Hopkins Medicine's Myth vs Fact webpage, click here

What is a vaccine?

A vaccine is a simple, safe, and effective way to protect your body against harmful diseases by triggering your body's natural immune system to build resistance. With all vaccines, the goal is for our bodies to develop "memory" T-lymphocytes and B-lymphocytes, which remember how to fight the virus in the future. 

What type of vaccines do we have for-19?

In the United States, there are two types of vaccines currently authorized - mRNA and adenovirus or viral vector vaccines. The Pfizer and Moderna are mRNA vaccines and the Johnson & Johnson is an adenovirus/viral vector vaccine.

Will the COVID-19 vaccine give me COVID-19?

No. None of the currently approved or authorized vaccines contain the live SARS-COV2 and cannot give you COVID-19.

What is the effectiveness of the COVID-19 vaccine?

Both Pfizer and Moderna have shown a real-world efficacy rate of 90% and the Johnson & Johnson vaccine is over 65%. All three are effective in both preventing illness and preventing severe illness and/or hospitalization.

How are vaccines administered?

Pfizer, Moderna, and Johnson & Johnson are administered intramuscularly (into the muscle) via an injection. 

Do both Moderna and Pfizer require two doses? 

Yes, Moderna requires its second dose within 28 days of the first dose and Pfizer requires its second dose within 21 days of the first dose. 

How do we know MRNA vaccines are safe?

mRNA vaccine development has long been studied and is proving to be effective. The technology utilized to make these vaccines has been developed over the last 20 years. Messenger RNA (mRNA) vaccines have been studied for over a decade in influenza, Zika, rabies, and cytomegalovirus (CMV), and new cancer treatments. mRNA vaccines carry genetic material that helps our cells make a harmless piece of "spike protein," found on the surface of the SARS-CoV2 virus. The spike protein triggers an immune response to protect us from getting infected if the SARS-CoV-2 virus enters our bodies. mRNA vaccines do not change our DNA and cannot give someone COVID-19.

How do we know the vaccines are safe?

It is the job and priority of the U.S. vaccine safety system to make sure that all vaccines are as safe as possible. The new COVID-19 vaccines have been evaluated in tens of thousands of individuals, who volunteered to be vaccinated and to participate in clinical trials. These trials helped the Food and Drug Administration (FDA) to determine the safety of the vaccine.

Will problems be watched closely regarding the vaccine?

Yes, even though no safety issues arose during the clinical trial, the CDC and other federal partners will continue to monitor the new vaccines for serious side effects.

Is there a possibility that the effectiveness of the vaccines can be different after the clinical trials?

Many factors can affect effectiveness in real-world situations. Those factors can include transportation, storage, and the administration of the vaccine. Vaccine effectiveness can also be affected by the differences in the underlying medical conditions of those being vaccinated. 

What is Emergency Use Authorization (EUA)?

What is EUA?  An Emergency Use Authorization (EUA) gives the FDA authority to allow the use of unapproved medical products, or unapproved uses of approved medical products, to diagnose, treat, or prevent serious or life-threatening diseases when certain criteria are met, including that there are no adequate, approved, and available alternatives.  Learn more about EUAs from the FDA's website.

Where can I learn more about each vaccine?