Why Immune Systems Age Differently in Men and Women

Research indicates that biological sex significantly influences how the immune system ages, with women generally experiencing more substantial age-related changes than men. These differences impact how individuals respond to infections and the prevalence of certain diseases throughout their lifetimes.

According to reporting from Medical Xpress on April 10, 2026, population statistics show that men are more susceptible to cancers and infections than women.

This susceptibility is reflected in specific health outcomes. A study published in Public Policy Aging Reports on November 22, 2023, notes that men are more susceptible to infectious diseases and tend to experience these diseases more severely.

As a specific example, the death rate from COVID-19 is 1.5 to 2-fold higher for men than for women.

Timing and Nature of Immune Changes

The timing of immune system shifts differs markedly between the sexes. Findings published in iScience show that women experience differences in distinct immune cell populations early in their lifetimes.

Specifically, women exhibit elevated counts of naive CD8+ T cells and B memory cells during early life.

In contrast, differences in immune cell counts for men are postponed until middle age or late age.

The nature of these changes also varies by cell type. Data from the National Institute on Aging, published October 8, 2020, indicates that women showed little age-related change in B cells.

However, B cells in older men showed a major loss in chromatin accessibility, a factor that relates to how these cells function.

Public Health Context and Aging Populations

Understanding these sex-specific trajectories is critical as the global population continues to age. The World Health Organization reports that the proportion of adults older than 65 years is expected to increase from 10% to 20% of the total world population by 2050.

This demographic shift is expected to increase the burden on healthcare systems globally.

Older adults are more prone to several chronic conditions, including:

• Cancer
• Diabetes
• Heart diseases
• Infections

Because of these vulnerabilities, older adults are more likely to be hospitalized or die from these diseases.

Researchers emphasize that not all individuals age at the same rate or in the same way. The study published in Public Policy Aging Reports on November 22, 2023, suggests that the fact that aging varies can be harnessed to better understand and potentially slow down the process.

By combining the factors of biological sex and aging, researchers aim to explore how these elements together affect the overall immune system and the responsiveness to vaccinations.