Study explains why COVID-19 is more fatal to seniors

Did you know adults over the age of 75 have a 13-fold higher risk of dying from COVID-19 compared to those under 65 [1]? This startling statistic has puzzled researchers since the pandemic’s onset in 2020. 

Despite being recognized early that seniors are at substantial risk for severe outcomes, the precise mechanisms contributing to this increased susceptibility have remained somewhat elusive.

Recent findings from a comprehensive multicenter clinical study provide new insights into this critical issue. 

Dr. Hoang Van Phan, the lead author of the study published in Science Translational Medicine, stated that the research focused on understanding how age influences the body’s response to the SARS-CoV-2 virus [2]​​. 

“We evaluated the impact of aging on the host immune response in the blood and the upper airway, as well as in the nasal microbiome,” reported Phan [2]​​.

The study’s findings are eye-opening. Older adults not only show an increased viral load upon hospital admission but also experience delayed viral clearance and significant alterations in immune response. 

“Older age correlated with increased SARS-CoV-2 viral abundance, delayed viral clearance, and increased type I interferon gene expression in both the blood and upper airway,” explained Phan [2]​​.

Furthermore, the immune system appears to function differently with age. “We also observed age-dependent up-regulation of innate immune signaling pathways and down-regulation of adaptive immune signaling pathways,” stated Phan. 

This shift results in a decreased population of naïve T and B cells, crucial components of the adaptive immune system, and an increase in monocyte production from the innate immune system [2]​​​​.

One of the most concerning findings was the sustained activation of pro-inflammatory genes in older adults, which suggests an impaired ability to resolve inflammation. 

“Older individuals demonstrated a persistent induction of pro-inflammatory genes and serum chemokines compared with younger individuals,” Phan noted. This ongoing inflammation is likely a key factor in the severe outcomes observed in the elderly [2]​​​​.

Markers of disease severity, such as interleukin-6, were found to be most pronounced in the oldest patients, aligning with their increased risk. 

The study not only clarifies why seniors are more vulnerable to COVID-19 but also opens the door to potential treatments. 

“These differences raise the possibility that older adults with severe COVID-19 may respond differently, and perhaps more favorably, to immunomodulatory therapies directed at certain inflammatory cytokines,” Phan concluded [2]​​​​.

Understanding the biological impact of aging on COVID-19 susceptibility is crucial for developing targeted interventions that could significantly improve outcomes for seniors. 

As the world continues to manage the pandemic, insights like these are crucial for safeguarding our most vulnerable populations.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7644030/
[2] https://medicalxpress.com/news/2024-06-age-linked-severe-fatal-covid.html 

Photograph: Macro_Media/Envato
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