COVID-19 Vaccination Fact Sheet

Four vaccines are currently available. The vaccines from Pfizer and from Moderna both use messenger RNA (mRNA) technology.This technology does not use any live virus particles. You will not be exposed to the virus that causes COVID-19.

A third vaccine, by Johnson & Johnson (J & J), is a viral vector vaccine. It is made from an inactivated adenovirus, the virus that causes the common cold, and contains a piece of DNA that instructs the body to make the COVID-19 spike protein. The use of genetic instructions makes the Johnson & Johnson vaccine similar to, but not exactly the same as the Pfizer and Moderna vaccines. 

A fourth, Novavax, is a subunit protein vaccine and requires two shots. It uses “a combination of spike proteins and an immune stimulant to provoke an immune response against the virus that causes COVID-19,” according to Johns Hopkins.

Vaccines can prevent or reduce the severity of nearly every variant of COVID-19.

Boosters are recommended for everyone eligible ages 5years and older. Further booster guidance is expected in the fall

CDC recommends COVID-19 primary series vaccines for everyone ages 6 months and older, and COVID-19 boosters for everyone eligible ages 5 years and older.

Getting a COVID-19 vaccine after you recover from COVID-19 infection provides added protection against COVID-19.

People who are moderately or severely immunocompromised have different recommendations for COVID-19 vaccines, including boosters.

I. Safety and Effectiveness

Is the vaccine safe and effective?

To be effective, both of these vaccines and the Norovax vaccine 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.

The J & J vaccine was 85% effective in preventing severe/critical illness and 66% effective in preventing symptomatic illness 28 days after vaccination. Importantly, it was 100% effective in preventing hospitalization and death from COVID-19. The J & J vaccine only requires one shot to be effective.

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.

The only serious side effect, a blood clotting disorder, occurred among 15 women out of the nearly 8 million people who received the Johnson & Johnson vaccine. A review by a committee of scientific experts concluded that the vaccine is safe for use because the risk is extremely small and the vaccine’s benefits far outweigh its risks. The committee’s review also concluded that failing to use it would lead to many more deaths than the clotting disorder might cause.

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 may be able to 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 Pfizer and Moderna 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.

Johnson & Johnson (J & J), is a viral vector vaccine. It is made from an inactivated adenovirus, the virus that causes the common cold, and contains a piece of DNA that instructs the body to make the COVID-19 spike protein. J & J used a modified adenovirus that can enter cells but can’t replicate inside them or cause illness. This in turn triggers an immune system response, giving you protection should you ever be exposed to the real virus in the future. The use of genetic instructions makes the Johnson & Johnson vaccine similar to, but not exactly the same as the Pfizer and Moderna vaccines.

With the Noravax vaccine, “instead of injecting the genetic recipe, we actually inject the protein. It [uses] a combination of spike proteins that form what are called nanoparticles, which group together. The Novavax vaccine also has an adjuvant, an immune stimulant to get a better immune response. In some ways, this is an older technology. The protein is made outside of the human body and then injected into us, and that induces the immune response.”

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.