SACRAMENTO, Calif. — There are now two different COVID-19 vaccines that have been given approval for emergency use by the FDA in the United States. The Pfizer and Moderna vaccines are both highly effective and use similar technology to fight against the coronavirus, but there are some crucial ways the two vaccines differ.

Dr. Timothy Albertson, the Chair of Internal Medicine at UC Davis Health, broke down the similarities and differences between the two available vaccines.

What You Need To Know

  • The Pfizer and Moderna COVID-19 vaccines have each been given approval for emergency use by the FDA

  • Moderna’s vaccine has been approved for those 18 and older, while Pfizer permits people 16 and older to receive its vaccine

  • Pfizer and Moderna both use the same mRNA technologies and have similar side-effects

  • Pfizer's vaccine is 95% effective, while Moderna's is 94.1% effective

Dr. Albertson has been involved in multiple clinical trials since the coronavirus outbreak last March and says one of the main differences between the Pfizer and Moderna vaccines is the amount of time a person must wait between receiving the first and second dose.

For the Pfizer vaccine, the booster shot occurs 21 days after the initial dose, while people who get the Moderna vaccine must wait 28 days in between doses.

“That’s what they chose and I don’t think they had a lot of data that suggests that 21 days or 28 days are any better or worse,” Dr. Albertson added.

The two vaccines are also stored at different temperatures. Pfizer’s must be placed in a minus 90 degrees fahrenheit freezer, while the Moderna vaccine can be kept at much warmer temperatures, similar to the average home freezer.

“Not any small hospital and certainly most clinics don’t have a minus 90 refrigerators, so that makes it a little different,” Dr. Albertson noted.

Moderna’s vaccine is approved for emergency use for those 18 and older. However, Pfizer permits people 16 and older to receive its vaccine.

Dr. Albertson explained that each COVID-19 vaccine uses the same new mRNA technology to create antibodies that fight against the virus.

Pfizer and Moderna also reported similar side-effects, such as fever, achiness and pain where people received the shot.

“I haven’t seen any data that really one is less responsive than the other, again they’re both working through the same mechanism,” Dr. Albertson added.

He says it doesn’t matter whether someone receives the Pfizer or Moderna vaccine because both are around 95% effective and safe.

“We think they are effective and we base that on two months' data and that’s what got us the emergency use authorization,” Dr. Albertson said.

So far, a total of 10,000 health care workers at UC Davis have been vaccinated. Dr. Albertson says he hopes to see this number increase throughout the state so more Californians can develop immunity to the virus.