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The Moderna vaccine doesn’t have the same cold storage requirements as the Pfizer vaccine. PAUL SANCYA/Getty Images
  • Experts say the COVID-19 vaccine you receive will probably depend on where you live and what medical facility you get the inoculation.
  • They note that the Pfizer vaccine requires storage at colder temperatures than the Moderna vaccine, so smaller facilities and more rural areas will probably use the Moderna product.
  • Doctors told Healthline that they don’t really have a preference. They will use what’s available.

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This week, the healthcare workers and nursing home residents who got the first of the Pfizer COVID-19 vaccines will line up again to get dose number two.

It was less than a month ago that the Food and Drug Administration (FDA) gave the vaccine emergency use authorization.

The following week, the Moderna vaccine also got the FDA blessing.

The latest data from the Centers for Disease Control and Prevention (CDC) says slightly more than 5 million people have received their first dose of the vaccine so far.

Are doctors seeing differences in the two vaccines?

Does one have an advantage over the other?

Do doctors have a preference?

Experts say the vaccine safety profiles and effectiveness are similar.

Where they differ substantially is the logistics of handling and storing them.

“The biggest disadvantage to the Pfizer vaccine is just how it needs to be stored, and that it requires special handling and freezing to maintain the proper cold chain,” Dr. Eric Cioe-Pena, director of global health at Northwell Health in New York, told Healthline.

That’s a point many experts focused on when interviewed for this story.

Both vaccines require cold storage, but the Pfizer vaccine has to be stored in ultra cold temperatures, often requiring special freezers.

“Moderna’s storage may make it more suitable for smaller, rural sites,” said Dr. Rob Davidson, an emergency physician in Michigan and the executive director of the Committee to Protect Medicare.

“[You] can buy 100 dose allotments versus 975 dose allotment for Pfizer,” he told Healthline.

Both vaccines have produced severe allergic reactions in a handful of cases.

In Boston, a doctor used his own EpiPen to treat his anaphylactic reaction to getting the Moderna vaccine.

Right after the first severe reactions to the Pfizer vaccine, the National Institutes of Health began devising a study to find out why the potentially life threatening allergic reactions were happening.

Dr. Sam Sun is the director of the inDemic Foundation, a team of scientists, doctors, and epidemiologists with expertise on COVID-19 therapeutics and vaccines.

He said researchers are looking at a chemical in both vaccines that’s widely used in other medicines, foods, and cosmetics.

“Both vaccines contain PEG-2000, which might be causing rare cases of anaphylaxis,” Sun told Healthline.

There’s also more research on whether Moderna may offer some protection against asymptomatic disease, information that was part of a secondary outcome of the study.

“Preliminary analysis suggests that the Moderna vaccine prevents SARS-CoV-2… in addition to preventing COVID-19 disease,” said Sun.

“It is important to show that vaccination prevents SARS-CoV-2 infection, so that we have some assurance that vaccinated individuals are at much lower risk of spreading SARS-CoV-2 to unvaccinated, vulnerable contacts, or asymptomatic transmission,” Sun explained.

“This suggests that there was about a 60 percent relative risk reduction,” said Davidson. “The numbers are so small that it is difficult to draw conclusions as the study wasn’t powered to detect this difference, but it is promising. I have not seen similar data for the Pfizer vaccine.”

“Neither company has demonstrated conclusively that their vaccines prevent asymptomatic transmission, but they are actively investigating this,” Sun noted.

“I received the Moderna vaccine because my hospital is rural and small. It does not have the freezers needed to store the Pfizer,” Davidson said.

“My wife works out of a different, larger hospital in the area, and she received the Pfizer vaccine,” he said. “We both feel equally protected.”

“I’ll take whichever one I can get — that was my attitude when I got the vaccine,” said Dr. Paul A. Offit, director of the Vaccine Education Center and a pediatrician and infectious disease specialist at Children’s Hospital of Philadelphia.

“You need to get whatever you can get because we need a lot more vaccine to be made. We need to mass produce this at a much higher level than we’re doing,” he told Healthline.

The rollout of the vaccines is well under the Trump administration promise of 20 million people vaccinated by the end of 2020.

According to the CDC vaccine tracker, more than 17 million doses of vaccine have been distributed. That’s 12 million dosages sitting around unused that could expire.

Adding to that, the United States currently only has enough vaccinations ordered to inoculate 185 million Americans by the end of June.

There’s no national plan in place at the moment and federal officials are currently leaving distribution details up to the states.

One theory of why the states are lagging behind is that their hospitals and health systems are overwhelmed treating people with COVID-19.

Moderna officials just promised to ramp up their production to make a minimum of 600 million doses this year. The company says it will have 100 million doses ready by the end of March and another 100 million by the end of June.

“We should be doing what my hospital did,” said Offit. “We were called to the Stokes Auditorium. There were nurses sitting on the stage ready to give the vaccines. A pharmacist was making sure that once the vaccines got reconstituted they didn’t just hang out for more than 6 hours.”

“You got your shot, and you went to another part of the auditorium to wait and make sure you don’t have an allergic reaction. We vaccinated roughly 12 people every 30 minutes,” he said.

“We should be doing that with everybody — not just hospital workers, but with transportation workers, teachers — and have these mass vaccination campaigns throughout the country. That’s the way to do it,” he added.