A team of researchers from Nagoya University in Japan has discovered that human behavior plays a crucial role in the evolution of new strains of SARS-CoV-2, the virus responsible for Covid-19. The study, published in Nature Communications, provides valuable insights into how environmental factors, such as confinement and isolation measures, can influence disease agents’ evolution.

The coronavirus has evolved to become more transmissible earlier in its life cycle, which is a significant finding for public health strategies aimed at controlling outbreaks. By isolating sick people and using lockdowns to control outbreaks, people can alter the evolution of the virus in different ways. However, predicting how these changes occur is vital to developing adaptive treatments and interventions.

One important concept in this interaction is viral load. This refers to the amount or concentration of virus present per ml of body fluid. In the case of SARS-CoV-2, higher viral loads increase the risk of transmission through droplets. Viral load refers to the potential to transmit a virus to other people, with viruses like Ebola having an extremely high viral load while the common cold has a low one.

The research group led by Professor Shingo Iwami used mathematical models with an artificial intelligence component to investigate previously published clinical data. They found that SARS-CoV-2 variants that were most successful in spreading had an earlier and higher peak viral load, as well as a shorter duration of infection. Additionally, reduced incubation periods and higher proportions of asymptomatic infections recorded as the virus mutated also influenced its evolution.

Iwami and his colleagues suggest that changes in human behavior designed to limit transmission increase selection pressure on the virus, leading to SARS-CoV-2 being transmitted primarily during asymptomatic and pre-symptomatic periods, which occur earlier in its infectious cycle. As a result, peak viral loads have advanced to this period to spread more efficiently during pre-symptomatic stages. According to the scientists, when evaluating public health strategies aimed at controlling Covid-19 and future pandemics caused by pathogens like coronaviruses

By Editor

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