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More good news about a COVID-19 vaccine; Moderna’s candidate shows high efficacy

A look at the differences between the vaccines Pfizer and Moderna are producing and what it means for you

SHARE More good news about a COVID-19 vaccine; Moderna’s candidate shows high efficacy

Flu shots have long been injected deep into muscle, requiring a needle an inch long or longer. Both Pfizer and Moderna have announced promising results from vaccine trials to battle COVID-19

Jacquelyn Martin, Associated Press

Amid soaring case counts and increasingly crunched hospital systems, a spot of good news emerged Monday morning as Moderna announced its mRNA vaccine shows a 94.5% efficacy rate.

Moderna is the second company to share promising results from a phase 3 trial — a large scale assessment of vaccine safety and efficacy — that showed a two-dose vaccine was effective at preventing COVID-19.

Its data showed that two weeks after the second vaccine shot, 95 people in the study group had contracted COVID-19 — 90 who had received a placebo and 5 who’d gotten the vaccine. Of the 95 COVID-19 cases, 11 cases were severe, and all were placebo recipients.

“This is a pivotal moment in the development of our COVID-19 vaccine candidate,” Moderna’s CEO, Stéphane Bancel, said Monday morning in a release.

The company said it will ask for FDA emergency use authorization “in the coming weeks,” the next step toward getting the vaccine out to health care workers and the other high-priority groups: adults over 65 years old, those with high-risk medical conditions and essential workers. Together, those groups comprise more than half of all U.S. adults.

From there, the vaccine will be made available to the general public, though likely not before spring 2021.

Last week, the US/Germany team of Pfizer and BioNTech made headlines when they announced their mRNA vaccine showed more than 90% efficacy. They will be submitting their vaccine for emergency use authorization as soon as they have two months of safety data following the second dose, which they expect to happen in the third week of November.

Here’s what you need to know about these two vaccine candidates and what this could mean for you:

Both vaccines

  • Both Moderna’s and Pfizer’s vaccines are mRNA vaccines, which means that unlike the annual flu vaccine or some childhood vaccines, they don’t contain any live or dead novel coronavirus and cannot give you COVID-19. Instead, they contain genetic instructions that tell your body to make a harmless spike protein — the same protein the novel coronavirus uses to attack healthy cells. This triggers an immune response that prepares your body to respond should an actual novel coronavirus encounter occur.
  • While the vaccine will not give you COVID-19, and no serious side effects have been noted, some have reported mild to moderate effects following vaccination, including injection site pain, fatigue, muscle pain, joint pain and headache, according to the Moderna report.
  • Both vaccines require two doses, given either 21 or 28 days apart.
  • Despite optimism from public health officials, Moderna notes that “the forward-looking statements in this press release are neither promises nor guarantees,” while Pfizer outlines in a lengthy paragraph the “substantial risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statements.”

They are referring to the fact that the technology is still being developed, there’s never been an FDA-approved mRNA vaccine before, their findings are still not peer-reviewed and they could experience significant supply chain and distribution issues.


  • In addition to announcing efficacy, Moderna also announced Monday its vaccine will remain stable for 30 days in a standard home or medical refrigerator — an increase from an earlier estimate of only a week of refrigeration stability. In a freezer below -20 degrees C (-4 degrees F) the vaccine could remain stable for up to 6 months. Once taken out of the refrigerator to administer, the vaccine will remain stable for up to 12 hours, according to a company release.
  • Moderna’s study pool is 30,000 people ages 18 and older, with 25,654 who have received their second vaccination. The pool includes more than 7,000 Americans over the age of 65, plus 5,000 people who are medically high-risk (diabetes, severe obesity and cardiac disease). It also includes 11,000-plus participants from communities of color, with more than 6,000 people who identify as Hispanic or LatinX and more than 3,000 who identify as Black or African American.


  • Pfizer was not part of Operation Warp Speed; however, in July the U.S. government bought 100 million doses of the independent vaccine for $1.95 billion — with the potential to buy 500 million more, according to a company press release earlier this summer. In that release, Pfizer also indicated that Americans would receive the vaccine for free, “consistent with the U.S. government’s commitment for free access for COVID-19 vaccines.”

  • Pfizer’s phase 3 clinical trial data come from more than 43,000 people worldwide, 38,955 who have received a second dose of the vaccine candidate as of Nov. 8. Of these, 42% of global participants and 30% of US participants have racially and ethnically diverse backgrounds.
  • Pfizer and BioNTech are continuing to enroll participants in their study until they reach a total of 164 confirmed COVID-19 cases. They will also study if the vaccine is effective for those who have already had COVID-19. All participants will be monitored for two years after the second dose to gauge long-term efficacy and any safety issues.
  • Pfizer and BioNTech’s mRNA vaccine requires extensive cold-chain storage at -70 degrees C (-94 degrees F) and will be shipped in special insulated containers using dry ice that must be replenished every few days.