Moderna COVID-19 Vaccine Only Slightly More Effective Than Pfizer

While Moderna has a slight edge over Pfizer, both vaccines prove to be extremely effective, especially in the prevention of severe disease, hospitalization, and death. Experts say getting whichever vaccine is most accessible to you is the best approach.

The first comparison of the Pfizer-BioNTech and Moderna COVID-19 vaccines showed that both vaccines are incredibly protective against the disease, and people are urged to get whichever vaccine is the most readily available in their area. mixetto/Getty Images
  • The first head-to-head comparison of the Pfizer and Moderna vaccines is revealed.
  • While Moderna has a slight edge over Pfizer, both vaccines prove to be extremely effective, especially in the prevention of severe disease, hospitalization, and death.
  • Experts say getting whichever vaccine is most accessible to you is the best approach.
  • Researchers are currently studying how effective these vaccines are against the Omicron variant, but most experts are confident the vaccines will continue to provide a meaningful level of protection.
  • The one-shot Johnson & Johnson COVID-19 vaccine was not included in this study.

Since the Food and Drug Administration (FDA) approved emergency use of COVID-19 vaccines, many people have wondered whether one vaccine is better than the other.

Now, the first head-to-head comparison of the Pfizer-BioNTech and Moderna vaccines has been released.

Researchers from the Department of Veterans Affairs, Harvard T.H. Chan School of Public Health, and Brigham and Women’s Hospital teamed up to analyze electronic health records of nearly 220,000 veterans who received two doses of the Moderna vaccine and about 220,000 veterans who received two doses of the Pfizer-BioNTech vaccine.

“We knew from early randomized trials that the Pfizer-BioNTech and Moderna vaccines were both remarkably effective at preventing symptomatic disease. We also knew that detecting any subtle differences between their effectiveness would require a head-to-head comparison in a very large sample — much larger than would be practical in a randomized trial,” Dr. Barbra A. Dickerman, first author of the study, told Healthline.

Effectiveness of the vaccines was measured based on:

  • documented, or asymptomatic, infection
  • symptomatic infection
  • hospitalization
  • ICU admission
  • death

The results show that both vaccines are significantly effective.

However, Moderna showed a slight edge by offering an increased level of protection, including a 21 percent lower risk of documented infection and 41 percent lower risk of hospitalization.

“That looks like a big number, but look at the two numbers they’re comparing. They already start out very small, so it’s like the difference of 94 percent and 92 percent,” Dr. William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center in Nashville, told Healthline.

The percentages are derived from the estimated risk of documented (asymptomatic) infection being 4.52 events per 1,000 people in the Moderna vaccine group and 5.75 events per 1,000 people in the Pfizer-BioNTech group.

This resulted in an excess of 1.23 cases of documented infection per 1,000 people in the Pfizer-BioNTech group.

“You stand back a little and you can’t see that difference. It’s like two baseball players hitting home runs, but one of the home runs got a little bit higher in the seats than the other,” said Schaffner. “It’s great that we have two excellent vaccines.”

He said the vaccines are so similar that he wouldn’t be surprised if another head-to-head comparison in another population “turned this upside down because the differences really are very, very small.”

The differences between the two vaccines remained consistently small for severity of disease:

  • For hospitalizations, the Pfizer-BioNTech group had 0.55 excess cases per 1,000 people.
  • For ICU cases, the difference dropped to 0.10 excess cases per 1,000 people.
  • For deaths, the Pfizer-BioNTech vaccine recipients had 0.02 excess events for every 1,000 people.

“Clearly, the differences between the vaccines get even smaller as we consider the more serious outcomes. This is why I would contend that it is more important to get vaccinated than to worry about which vaccine you are receiving,” Dr. Mark Fierstein, internal medicine specialist at NYU Langone Ambulatory Care Lake Success, told Healthline.

While the vaccines both use mRNA technology, they are not identical. Because of this, Fierstein said it’s not surprising that the immune system, which is made of many elements, might not react in precisely the same way to the two vaccines.

“In fact, the real surprise here could be that the vaccines are so similar; that the differences that were observed were not greater,” he said.

Get Moderna or Pfizer, it doesn’t matter

If you haven’t gotten the vaccine yet, Dickerman said to get whichever one is most convenient and accessible to you.

“Given the high effectiveness of both vaccines, either one is strongly recommended to any individual offered the choice between the two,” she said.

While Dickerman pointed out that the study was not designed to compare how well vaccines work after an additional booster dose, Schaffner said again to take the shot that’s most accessible.

In October 2020, the FDA approved the use of mixing and maxing vaccine boosters.

“You don’t have to hunt all over town to find Moderna. If Pfizer is convenient, get it and vice versa, because once again the difference between the two is so tiny, I think it has little if any clinical significance,” Schaffner said. “I would be pleased if any of my patients or any members of my family got either of these vaccines.”

As this head-to-head study shows both vaccines to be effective, he points out that other studies have proved both vaccines to have similar side effects.

“In the infectious disease community, we’re all pretty comfortable that these two vaccines have comparable side effects,” said Schaffner.

Will the vaccines protect against Omicron?

While the emergence of the Omicron variant raises questions regarding whether the current vaccines will continue to provide protection, Schaffner said the focus should remain on getting vaccinated and boosted.

“I have been reminding people for the past several days that if you look out in every city and town in the United States there’s Delta, and Delta is spreading today in your neighborhood — infecting people, making them sick, sending them to the hospital and, I’m afraid, causing the deaths of people — so the issue in front of us right now is Delta, and both these vaccines provide very superior protection against Delta,” Schaffner said.

If it turns out there is some erosion of protection from the vaccines against Omicron, Schaffner said the vaccines are likely to provide partial protection.

“And partial protection is always better than no protection. There’s every reason to get vaccinated today,” he said.

He believes if everyone who has not been vaccinated and if everyone who is due for a booster got vaccinated now, “in 2 weeks, COVID in the United States would drop like a stone.”

Fierstein agreed that the take-home lesson is clearly to be vaccinated and then boosted.

However, when it comes to Omicron, he pointed out that scientists will continue to research the following:

  • Is it more contagious than Delta and other variants already on the scene?
  • Is it more or less severe than the other variants?
  • Do the vaccines we already have afford protection against this variant with anywhere near the effectiveness they provided against Delta and the earlier variants?

“If anything, this study would suggest, although not assure, that they are both likely to provide similar degrees of protection, whatever that degree is,” said Fierstein.

What about the J&J vaccine?

While Dickerman and team did not comment on why the Johnson & Johnson vaccine was not part of their study, Schaffner said a possible reason is that it was not given as much in the Veterans Affairs system.

“Other studies have already indicated that J&J, which started out as the one-and-done vaccine, clearly is one and not quite done. It needed two doses, and so we know in this retrospective study, J&J would not perform anywhere close to either of these vaccines,” said Schaffner.

This story originally appeared on: Healthline.com - Author:Cathy Cassata