Moderna or Pfizer: Which vaccine is a better booster? Experts weigh inBoth Pfizer's and Moderna's COVID-19 vaccines offer significant protection against breakthrough infections and hospitalizations but new research shows Moderna's vaccine may offer slightly better protection compared to Pfizer.

Social Sharing

New research shows Moderna may provide slightly more protection against breakthrough infections

CBC News(Rogelio V. Solis/The Associated Press)commentsThe Dose21:31What do we know about how the Moderna and Pfizer vaccines measure up?

Until there's some future vaccine designed specifically to target the highly transmissible Omicron variant, adults in Canada are encouraged to get their booster shot as soon as possible — which means either Pfizer or Moderna.

Both mRNA vaccines offer significant protection against breakthrough infections and hospitalizations, but new research from data collected before Omicron hit shows Moderna's vaccine may offer slightly better protection compared to Pfizer.

That may surprise people who had been turning Moderna down, said Kelly Grindrod, a pharmacist and associate professor at the University of Waterloo school of pharmacy.

"They walk away from it because they think it's a lesser vaccine," she told Dr. Brian Goldman, host of CBC podcast The Dose. "Butthe evidence doesn't say Moderna is a lesser vaccine. Actually, it's quite the opposite." 

• ASK CBC NEWSWhich COVID-19 booster shot should I get? Your questions answered

• Half of people offered Moderna vaccine refuse it if they want Pfizer, Ontario pharmacists say

A study publishedin the peer-reviewed Journal of the American Medical Association (JAMA) last week shows adults who received two doses of the Moderna vaccine had a lower risk of hospitalization compared to those who received two doses of the Pfizer-BioNTech vaccine. The research used data from March to August of last year when Delta was the dominant variant.

As booster shots roll out across the country, Moderna may be a better choice for many over the age of 30 because of its slightly longer protection against infection, said Grindrod, the pharmacy vaccine lead for the Waterloo region.

New research around which vaccine is best for specific populations — and Omicron — is evolving, but there are a few key things you need to know right now.

How do the two vaccines compare?

Doctors and public health officials have said that people should get whichever booster shot is readily available to them. 

Both mRNA vaccines offer significant protection against COVID-19, Grindrod said, but studies comparing the two vaccines are showing Moderna has a slight edge. 

"Now, if you're someone who's in your 40s and is otherwise healthy, is that going to be a huge difference for you? Probably not. It might be just a very small difference," she said.

WATCH | Medical experts explain why the science behind boosters is sound:

The safe science behind COVID-19 booster shots

3 months agoDuration 1:55While some Canadians who have received their booster shots have later tested positive for COVID-19, medical experts agree that the science behind booster jabs is sound.(Alberta Health Services)

Take what you can get, doctors say

If you're 30-years-old or older and healthy, Grindrod said people should just take the first shot they can get. 

And if you received the AstraZeneca or Johnson & Johnson shots for your first two doses, getting either the Moderna or Pfizer boosters that are available will still offer strong protection against COVID-19. 

But if someone has a weakened immune system or has more risk factors, Grindrod leans towards recommending Moderna for a booster shot.

Dr. Iris Gorfinkel, a Toronto-based family doctor and vaccine researcher, emphasized that when it comes to reducing hospitalizations, both are "extremely effective."

"It's not promising to be perfect, even when it comes to hospitalizations. We're going to see breakthrough infections with either vaccines, but those breakthrough infections are few and far between compared to populations who remain unvaccinated."

Gorfinkel emphasizes that the differences between Pfizer and Moderna's vaccines "are small."

"The truth is they both really work well."

Both Pfizer and Moderna have launched studies of Omicron-specific boosters.

Gorfinkel said it will  take real-world study data comparing the vaccines head-to-head against Omicron to really tell if one offers better protection.

---

Written and produced by Stephanie Dubois, with files from Adam Miller and Amina Zafar.

(editor：)