Delayed Immune Responses May Drive COVID-19 Mortality Rates Among Men and Seniors

COVID-19 infections tend to be more severe among older adults and males, and a study in PLOS Biology suggests that varying immune responses to SARS-CoV-2 due to age and sex may be reliant on viral load and the time-course of infection, reports ScienceDaily . Researchers extracted and sequenced viral RNA from swabs collected from 430 COVID-19 positive cases and 54 negative controls, then analyzed the hosts' antiviral and immune responses across infection status, viral load, age, and sex. Immune cell responses were inactive until after three days following onset of infection, while immune cell composition and function fluctuated with viral loads to suggest a dysfunctional antiviral response in males and seniors. "Collectively, our data demonstrate that host responses to SARS-CoV-2 are dependent on viral load and infection time with observed differences due to age and sex that may contribute to disease severity," the authors concluded.