Story at a glance
- A new study from researchers at Harvard compared the efficacy of both the Pfizer-BioNTech and Moderna COVID vaccines.
- Researchers used the health records of close to 400,000 veterans for the study.
- While both vaccines are highly effective in offering protection against the virus, the Moderna vaccine is slightly better, the study claims.
A new study published in The New England Journal of Medicine claims that the Moderna COVID-19 vaccine is slightly more effective than the Pfizer inoculation.
The study was conducted by researchers from the CAUSALab at the Harvard T.H. Chan School of Public Health, Harvard Medical School, the Brigham and Women's Hospital along with the Veterans Administration was published online on Dec. 1.
Researchers stressed that both the Moderna and Pfizer vaccines are highly effective at preventing symptomatic COVID-19 and that the difference in protection against the virus offered by each vaccine is tiny.
The study used the health records of just under 440,000 U.S. veterans who were inoculated against the virus using the Pfizer vaccine, and the other half with the Moderna shots, between Jan. 4 and May 21 of this year, according to Harvard Magazine. All of the veterans used for the study were over the age of 18 and had not been infected with the virus prior to being vaccinated, the study notes.
Researchers found that those who received the Pfizer vaccine had a roughly 27 percent higher chance of becoming sick from COVID-19 during a 24-week follow up period to their first dose and a 70 percent greater chance of being hospitalized during that time frame when the alpha variant was dominant. This is compared to those who received the Moderna vaccine.
In addition, researchers estimated among the test groups there were 5.75 COVID-19 infections for every 1,000 people who received the Pfizer shot and 4.52 infections for every 1,000 people in the Moderna group during the time this year when the alpha COVID variant was dominant.
Once delta became the dominant variant, researchers found an extra 6.54 COVID-19 infections for every 1,000 people in the Pfizer vaccine group.
Researchers are unclear as to why there is a difference, albeit small, among the two vaccines but one theory is that it has to do with the different messenger RNA (mRNA) contents of the vaccines, the space between doses and the " lipid composition of the nanoparticles" used for packaging the mRNA, according to the study.
Both the Pfizer vaccine and the Moderna vaccine use lab-created mRNA to teach cells how to create a protein which then triggers an immune response in the body, according to the U.S. Centers for Disease Control and Prevention. The Moderna vaccine has just over three times as many micrograms of the mRNA content than the Pfizer-BioNTech inoculation, the study says.
Correction: An earlier version of this article erroneously stated the Pfizer-BioNTech vaccine had three times as many micrograms of mRNA as the Moderna COVID-19 vaccine.
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