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New research: Moderna, Pfizer vaccines for Covid-19 work better in men

Clinical trials showed the Moderna vaccine was 95.4% effective at preventing Covid cases for males, compared with 93.1% for females. For the Pfizer-BioNTech vaccine, the numbers are 96.4% for males and 93.7% for females.

By: Express News Service | New Delhi |
Updated: May 23, 2021 11:05:02 am
Empty vials of the Moderna Covid-19 vaccine lie in a box in Germany. (AP Photo/Matthias Schrader)

A researcher is raising awareness about an important subtlety in vaccines in use in the United States — the Moderna and Pfizer-BioNTech vaccines appear to work slightly better for males than for females. Researcher Morteza Mahmoudi of Michigan State University has published three peer-reviewed papers calling attention to the role of sex in nanomedicine studies, both in general and as they relate to coronavirus vaccines. The latest paper was published on Thursday in Nature Communications.

The Moderna and Pfizer vaccines use tiny orbs, or nanoparticles, to deliver their active ingredients to cells in our immune systems. Mahmoudi has been studying how and why nanomedicines can affect patients differently based on their sex. He believes this could be a factor with the vaccines.

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In his latest paper, Mahmoudi has advocated for systemic changes in how nanoparticles are used and studied in medicine. His article outlines challenges in researching the role of sex in nanomedicine performance along with strategies to mitigate them.

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For example, researchers may not have sufficient resources to perform their studies in cells or other samples taken from males and females. Yet these researchers and others may still interpret their results as being equally applicable to all sexes. To prevent this, Mahmoudi is calling for researchers to be more transparent and share sex-specific limitations of studies.

In the case of the Moderna vaccine, clinical trials showed it was 95.4% effective at preventing Covid cases for males, compared with 93.1% for females. For the Pfizer-BioNTech vaccine, the numbers are 96.4% for males and 93.7% for females.

Both vaccines use nanoparticles based on lipids. The pharma companies pack these tiny lipid-based particles with the vaccines’ active ingredients and essentially use the nanoparticles as delivery vehicles.

Working with researchers at Sapienza University of Rome, Mahmoudi designed an experiment to test whether lipid-based nanoparticles could be a reason behind the difference in vaccine efficacy for males and females. That study was published on May 13 in the journal Molecular Pharmacology.

The study found natural killer cells from female donors took up fewer nanoparticles than natural killer cells from male donors. Based on this model system, then, it is plausible that immune systems of males and females would respond differently to the vaccine.

Source: University of Michigan

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