- The Covid-19 fatality rate is higher among men and the elderly, as well as those with comorbidities
- Researchers have been trying to understand why this is the case
- According to recent research, delayed immune response in these two groups may be the answer
Older people, as well as those with comorbidities, have been found to be more vulnerable to severe Covid-19, the disease caused by SARS-CoV-2, since the early stages of the pandemic. And more recently, it has become clear why men as a group are also hit harder by the disease.
According to a latest study published in the open-access journal PLOS Biology this month, it appears that delayed immune response may drive higher Covid-19 mortality rates among men and the elderly.
Researching the underlying mechanism responsible
In August, Health24 reported on a study involving a team of researchers who analysed factors such as viral loads and the immune response in both males and females to find clues as to why men seem to be more susceptible to contracting Covid-19.
Among their observations was that females tend to produce more disease-fighting T-cells than males.
In spite of SARS-CoV-2’s minimal genetic diversity, the manifestation of Covid-19 infection has been found to vary among different patients. In the latest study, scientists, from the University of Washington wanted to understand the underlying mechanism that causes such diverse reactions in different hosts.
They extracted and sequenced viral RNA from swabs collected from 430 Covid-19 positive cases and 54 negative controls, and analysed the hosts' antiviral and immune responses across infection status, viral load, age and sex.
Clues from immune cell response
The researchers found that immune cell responses were not activated until after three days following the onset of infection.
They also wrote that the immune cell composition and function fluctuated with viral loads, suggesting a dysfunctional antiviral response in males and the elderly.
This means that varying immune responses to the virus – due to age and sex – may depend on viral load and the time-course of infection.
They wrote that while these findings have important implications for the development of immunomodulatory treatments (used to help regulate or normalise the immune system) for Covid-19, further studies are needed as swabs were taken from the nasopharynx.
According to the authors, this is not a sensitive anatomic location for accurately studying markers of systemic inflammation in Covid-19 patients.