MSU researcher: COVID-19 vaccines work better for men than women

Whitmer continues to reduce state pandemic restrictions


A Michigan State University researcher is raising awareness about an important subtlety in COVID-19 vaccine efficacy: Shots from Moderna and Pfizer appear to work slightly better for men than for women, according to a recent peer-reviewed article on nanomedicine studies. 

“We need to monitor these sex differences and report them to the scientific community and the public,” said Morteza Mahmoudi, an assistant professor in MSU’s Department of Radiology. “It can be very helpful in developing future strategies and as we prepare for future threats.”

Mahmoudi advocates systemic changes in how nanoparticles are used and studied in medicine, most recently in a May 20 article published in the journal “Nature Communications.”

In the article, he suggests that researchers may not have sufficient resources to perform their studies in cells or other samples taken from men and women. Yet these researchers and others may still interpret results as equally applicable to all sexes and skew their scientific conclusions. 

“We need to be more careful about the science that gets out,” Mahmoudi said in a statement. 

Clinical research shows that Moderna vaccines were 95.4% effective at preventing COVID-19 cases for men, compared with 93.1% for women. For Pfizer, it was 96.4% effective for men and 93.7% effective for women. The differences, Mahmoudi pointed out, are small but measurable — largely because of differences in immune system responses between men and women.

In related news…

Gov. Gretchen Whitmer lifted capacity restrictions for all outdoor events and boosting indoor capacity limits to 50% beginning on June 1, allowing indoor social gatherings like weddings and funerals to move closer to pre-pandemic normalcy.

Under the order, the state will no longer limit capacity limits anywhere at all beginning on July 1. 

Additionally, the updated orders enable employers to allow fully vaccinated staff to not wear face coverings and social distance, provided they also require non-vaccinated staff to keep them on.

Free drive-thru COVID-19 rapid saliva tests are available at the Ingham County Human Services Building, 5303 S. Cedar St. by appointments from 10 a.m. to 4 p.m., Monday through Thursday. Results are delivered within two days. Register online at


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