COVID-19 Vaccination Fact Sheet

Essential workers will be among the first in the nation to be eligible to take the new COVID-19 vaccine, which evidence shows will provide significant protection against the deadly disease. There are two vaccines that are or will soon be available from Pfizer and from Moderna, and both use messenger RNA (mRNA) technology. Unlike other vaccines, mRNA technology does not use any live virus particles. You will not be exposed to the virus that causes COVID-19.

I. Safety and Effectiveness

Is the vaccine safe and effective?

Both vaccines have a very high level of effectiveness: Pfizer has a 95 percent rate and Moderna has a 94 percent rate. To be effective, both vaccines require two shots, given a few weeks apart. Vaccines cannot be mixed and matched between doses. The length of vaccine-induced immunity is not known at this time, and booster shots may be required.

Some people who get a COVID-19 vaccine will experience side effects, particularly after a second dose. The side effects of the vaccine appear to be minor and temporary, including injection site pain, fatigue, and occasional fever, headache, or aching muscles and joints. These side effects fade within 1-2 days; no long-term effects have been detected thus far.

While the vaccine provides significant protection, it is not 100% effective. There is a slight chance that vaccinated individuals can still get infected with a mild case of the virus. Those who have taken the vaccine can also still spread the virus to others at home and at work. Thus it is critical that everyone continue to wear PPE and follow public health protocols for the foreseeable future.

II. Development and Approval

What’s in the vaccine?

The two vaccines both use messenger RNA (mRNA) technology. They do not use any live virus particles, meaning individuals will not be exposed to the virus that causes COVID-19. Instead, the messenger RNA -- a piece of genetic code -- directs cells to make the COVID-19 spike protein themselves, after which point the immune system creates the antibodies that fight COVID-19, providing a significant level of immunity.

How was it developed?

Because mRNA is easy to make in the laboratory, manufacturers saved years in development, accelerating the creation of the vaccine. In clinical trials for both vaccines, over 73,000 people from the U.S. and around the world received injections, including over 25,000 people from the communities most impacted by COVID-19, including Black, Latinx, and older people.

How does a vaccine get approved?

Vaccines must be approved by the Food and Drug Administration (FDA) before distribution. The FDA bases its decision to approve or not approve a vaccine on data from clinical trials. Independent experts and career scientists determine the vaccine’s safety based on the extent of side effects. If the clinical trial data shows enough evidence of efficacy and safety, the FDA will approve the vaccine.[1]


[1] Thanks to SEIU 1199UHE for developing this fact sheet, in close consultation with doctors and other medical professionals.