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FDA is about to authorize Moderna’s COVID-19 vaccine – here’s how it differs from Pfizer’s

Published Dec 18th, 2020 11:16AM EST
Coronavirus Vaccine
Image: Leigh Prather/Adobe

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  • An independent review panel voted overwhelmingly in favor of emergency authorization for Moderna’s coronavirus vaccine candidate.
  • The group advised the FDA to issue an EUA for the Moderna vaccine, just a week after making the same recommendation for the Pfizer/BioNTech drug.
  • The agency is expected to issue its emergency authorization on Friday, with vaccinations likely to start as soon as Monday.

The UK and US started COVID-19 vaccinations this month after the Pfizer/BioNTech vaccine received emergency authorizations in both countries. The European Union will soon approve the same drug, with the first Europeans to receive the first shot by the end of the year. By then, Americans will have access to a second COVID-19 vaccine candidate, as the Moderna drug just cleared the FDA’s Vaccines and Related Biological Products Advisory Committee’s review. The panel voted 20 to 0 to recommend Emergency Use Authorization (EUA) for the Moderna candidate on Thursday. The FDA is likely to issue the emergency authorization on Friday, with the first doses to go out to vaccination centers by Monday. That’s what happened last week with the Pfizer drug. The similarities between the two drugs would not end there, but there are plenty of differences between them as well.

The Moderna drug could be used to immunize up to 150 million people by mid-2021, The Guardian reports. That’s assuming the US government can successfully run the vaccination campaign. It’s not just logistics that can delay vaccination, but also the people who are reticent to the new drugs.

Both of them are mRNA drugs that codify the spike protein of the novel coronavirus virus. The aim is to teach the immune system to respond to this particular signature feature of the virus, which helps it infect cells. Once immunity is formed, neutralizing antibodies will block the spike protein, and specialized white blood cells will remember the spike protein.

Both vaccines require two doses, which have to be taken a few weeks apart; people are advised to come in for the second shot to receive the best possible protection. And both drugs have similar efficacy ratings and adverse effects warnings. The Pfizer drug is 95% effective at blocking COVID-19, while Moderna is slightly lower, at 94.1% efficacy. Moderna’s drug blocked severe COVID-19 in 100% of cases, however, which gives it a slight edge, at least on paper.

Both drugs require storage and transportation temperatures below freezing, but Moderna’s drug can survive in the kind of temperatures you’d find inside a regular freezer. The Pfizer drug needs to be transported and stored at -70C (-94F).

The Pfizer vaccine does have one advantage over Moderna: it’s authorized for patients as young as 16, while Moderna’s vaccine will be good for adults over 18. This requirement could lead to the government having to convince more adults to get immunized to compensate for the teenagers who won’t get access to the drug this year.

The side effects are similar for both vaccines and include pain where the injection is given and flu-like symptoms for a few days. The Pfizer drug generates an allergic reaction in some patients, a rare event that hasn’t been observed in the trial. But measures are in place to detect and treat anaphylaxis, should it occur after the first shot.

Moderna’s drug did have some allergic reactions in the trial. One happened in the placebo group, and the other in the vaccine group. One volunteer who got the vaccine candidate developed an allergic reaction more than 60 days after the injections, and it was related to a different medical procedure.

Chris Smith Senior Writer

Chris Smith has been covering consumer electronics ever since the iPhone revolutionized the industry in 2008. When he’s not writing about the most recent tech news for BGR, he brings his entertainment expertise to Marvel’s Cinematic Universe and other blockbuster franchises.

Outside of work, you’ll catch him streaming almost every new movie and TV show release as soon as it's available.