A team from Nagoya University (Japan) has revealed that human behavior, such as confinement and isolation measures, influence the evolution of new strains of SARS-CoV-2, the virus that causes COVID-19.
Corona virus became more infectious early in its life cycle.
The findings, published in Nature Communications, provide new insights into the relationship between people’s behavior and disease-causing agents.
Like any other living organism, viruses also evolve over time. Those who have a survival advantage become dominant. Many environmental factors, including human behavior, influence this development.
Humans can alter the evolution of viruses in a variety of ways, including isolating sick people and using lockdowns to control outbreaks. It is important to predict how these changes occur in order to develop adaptive treatments and interventions.
An important concept in this conversation is viral loadWhich refers to the amount or concentration of virus present per milliliter of body fluid.
In the case of SARS-CoV-2, high viral load in respiratory secretions increases the risk of transmission through droplets. Viral load refers to the ability to transmit the virus to other people.
For example, viruses like Ebola have an exceptionally high viral load, while the common cold has a low one. However, viruses must perform a careful balancing act, as increasing maximum viral load can be beneficial, but excessive viral load can make people sick enough to spread the virus to others.
The research group, led by Professor Shingo Iwami, identified trends by using mathematical models with an artificial intelligence component to examine previously published clinical data.
Thus, they found that the SARS-CoV-2 variants that were most successful in spreading had viral loads that peaked earlier and higher. However, as the virus evolved from variants From pre-alpha to delta versionThe duration of infection was short.
The researchers also found that the shorter incubation period and the higher proportion of asymptomatic infections as the virus mutated also affected the evolution of the virus.
There was a clear difference in the results. As the virus evolved from the Wuhan strain to the Delta strain, they observed a five-fold increase in peak viral load and a 1.5-fold increase in the number of days before viral load reached peak.
Iwami and colleagues suggest that changes in human behavior in response to the virus, designed to limit transmission, were increasing selection pressure on the virus. This led to SARS-CoV-2 circulating primarily during the asymptomatic and pre-symptomatic period, which occurs earlier in its infectious cycle. As a result, the peak viral load increased by this period and began to spread more effectively in the early pre-symptomatic stages.
According to scientists, when evaluating public health strategies in response to COVID-19 and potential future pandemic-causing pathogens, it is essential to consider the impact of changes in human behavior on the evolution patterns of the virus.
,We expect that immune pressure from vaccines and/or previous infections will accelerate the evolution of SARS-CoV-2 -Ewami explains-. “However, our study found that human behavior may also contribute to the evolution of the virus in a more complex way, suggesting the need to re-evaluate the evolution of the virus.”
Their study suggests the possibility that new coronavirus strains have evolved due to a complex interaction between clinical symptoms and human behavior.