What to know about the Pfizer-BioNTech and Moderna vaccines

CMH Outpatient Pharmacy Manager Jeff Chow injects MRI technician Connie Dubb with Moderna's vaccine to fight against COVID-19.

CMH Outpatient Pharmacy Manager Jeff Chow injects MRI technician Connie Dubb with Moderna’s vaccine in December 2020 to fight against COVID-19.

Both vaccines have been approved for emergency use in the U.S.


On Dec. 11, 2020, the FDA gave authorization for the emergency use of the Pfizer COVID-19 vaccine in the U.S. The Moderna COVID-19 vaccine received this authorization on Dec. 18, 2020. These vaccines are a big step forward in the fight against COVID-19.

The Pfizer and Moderna vaccines contain genetic material called messenger RNA (mRNA). This small piece of the coronavirus’s mRNA orders the cells in your body to make copies of a distinctive but harmless spike protein that appears on the surface of the coronavirus. These spike proteins trigger an immune reaction. Your body creates antibodies, which then protect you from getting sick if you’re exposed to the real virus later. 

It’s important to note that neither vaccine contains the real coronavirus, so getting them cannot give you COVID-19.

Anyone receiving the Pfizer or Moderna vaccines will need two shots given about three weeks to one month apart. According to the CDC, it usually takes a few weeks for immunity to develop after any vaccine. Trial data suggest that these vaccines start to offer some protection about 14 days after the first shot. 

For now, the Pfizer vaccine is approved for use in anyone age 16 or older, and Moderna’s is for anyone age 18 or older. 

In trials looking at preventing COVID-19, Pfizer’s vaccine was 95% effective, and Moderna’s was 94.1% effective. That’s very good. The FDA’s benchmark for vaccine approval was an efficacy rate of 50%. It is not yet clear how long the vaccine will provide protection or whether it prevents someone from spreading the virus, so it is important for those who get the vaccine to continue taking other safety precautions. 

There are only two contraindications, or reasons, not to receive a COVID-19 vaccine: an active COVID-19 infection or an allergy to a vaccine component. Pregnant women should consult with their OB-GYN before getting vaccinated. If you do not have a contraindication to receiving the vaccine, we strongly encourage you to consider getting one when it is offered to you.

* Since this article was published, other vaccines, such as the Johnson & Johnson one-shot vaccine, may have been approved by the U.S. FDA. 

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