Sex-Specific Differences in COVID-19 Outcomes Revealed in New Study

A recent study published in the Journal of Medical Virology has shed light on the differences in COVID-19 outcomes between males and females infected with various SARS-CoV-2 variants. The research, which was supported by the FDA Office of Women's Health fund, used age-matched female and male K18-hACE2 transgenic mice to investigate sex-specific differences in pathology after infection with SARS-CoV-2 variants 614 G, Delta, or Omicron.

Key Takeaways:

• The study found that Delta infection induced the most severe inflammation and pathology in nasal cavity and lung, followed by the 614 G and then Omicron variant.
• Sex differences in host responses to SARS-CoV-2 infection were variant-specific, with males showing increased pulmonary infiltration of CD163+ 'M2' macrophages, Ly6G+ neutrophils, and NKR-P1C + NK cells during early onset of infection after Delta infection.
• Females had increased lung CD4 + T cell recruitment after Omicron infection and significantly elevated lung MCP-1 secretion after Delta infection compared to males.
• Lung spatial transcriptomics data revealed that Delta-infected females had enriched gene pathways related to humoral immune response and interferon signaling, while males had enriched pathways associated with extracellular matrix production, chemokine signaling, and cell chemotaxis.
• The study emphasizes the importance of sex as a confounding factor for COVID-19 pathology and highlights the complex infection dynamics with respect to individual SARS-CoV-2 variants.

Statistics:

• 614 G variant was found to induce moderate inflammation and pathology in nasal cavity and lung.
• Delta variant induced the most severe inflammation and pathology in nasal cavity and lung, followed by the 614 G and then Omicron variant.
• Females showed increased expression of lung MCP-1 after Delta infection compared to males.
• After Omicron infection, females had increased lung CD4 + T cell recruitment compared to males.
• Lung spatial transcriptomics data revealed that Delta-infected females had enriched gene pathways related to humoral immune response and interferon signaling.

Sources:

• Dissecting Sex-specific Pathology In K18-hace2 Transgenic Mice Infected With Different Sars-cov-2 Variants. Journal of Medical Virology, 2025;97(7).
• Dissecting Sex-specific Pathology In K18-hace2 Transgenic Mice Infected With Different Sars-cov-2 Variants, 2025; P30 Digestive Disease Center Support Grant, P30 Cancer Center Support Grant, P30 Center for Precision Environmental Health, NIH S10 grant.
• U.S. Food and Drug Administration (FDA), Division of Systems Biology, Natl Ctr Toxicol Res, Jefferson, AR 72079, United States.