SARS‐CoV‐2 infection inIndiabucks the trend: Trained innate immunity?

Abstract

SARS‐CoV‐2, the causative agent of COVID‐19 pandemic caught the world unawares by its sudden onset in early 2020. Memories of the 1918 Spanish Flu were rekindled raising extreme fear for the virus, but in essence, it was the host and not the virus, which was deciding the outcome of the infection. Age, gender, and preexisting conditions played critical roles in shaping COVID‐19 outcome. People of lower socioeconomic strata were disproportionately affected in industrialized countries such as the United States. India, a developing country with more than 1.3 billion population, a large proportion of it being underprivileged and with substandard public health provider infrastructure, feared for the worst outcome given the sheer size and density of its population. Six months into the pandemic, a comparison of COVID‐19 morbidity and mortality data between India, the United States, and several European countries, reveal interesting trends. While most developed countries show curves expected for a fast‐spreading respiratory virus, India seems to have a slower trajectory. As a consequence, India may have gained on two fronts: the spread of the infection is unusually prolonged, thus leading to a curve that is “naturally flattened”; concomitantly the mortality rate, which is a reflection of the severity of the disease has been relatively low. I hypothesize that trained innate immunity, a new concept in immunology, may be the phenomenon behind this. Biocultural, socioecological, and socioeconomic determinants seem to be influencing the outcome of COVID‐19 in different regions/countries of the world.

High infectious disease burden as a basis for the observed high frequency of asymptomatic SARS-CoV-2 infections in sub-Saharan Africa

“…There is also the suggestion that the innate immune cells rely on epigenetic reprograming to obtain memory from previous exposure to an infectious agent. Thus, aside the innate immune cells being trained, they also retain memory in hematopoietic stem cell precursors in the bone marrow, which results in establishing long-lasting memory after several exposures to other infections 42 .…”

High infectious disease burden as a basis for the observed high frequency of asymptomatic SARS-CoV-2 infections in sub-Saharan Africa

“…Recent studies show that innate immune cells rely on epigenetic reprograming to obtain memory from previous exposure to an infectious agent. Thus, innate immune cells are trained to recognize these conserved pathogen molecules and retained memory in hematopoietic stem cell precursors in the bone marrow, resulting in establishment of long-lasting memory after several exposures to the same antigens from other infections 38 .…”

COVID-19: Is herd immunity the only option for fragile Yemen?

“…could be important protective factors. Since the SARS-CoV-2 does not stimulate a robust interferon, a trained cell would be more likely to raise a response against it compared to a non-trained cell ( Chinnaswamy, 2020 , Lipsitch et al, 2020 ). Although cross immunity and trained immunity may not decrease the transmission rate, it could possibly be the reason to limit disease severity and mortality.…”