Researchers from Nagoya University (Japan) have revealed that human behavior, such as confinements and isolation measures, affect the evolution of new strains of SARS-CoV-2, the virus that causes Covid-19. The findings, published in Nature Communications, provide new insights into the relationship between people’s behavior and disease-causing agents.
Humans are known to alter the evolution of viruses through their actions, but this is the first time it has been shown how this happens with SARS-CoV-2. By isolating sick people and using lockdowns to control outbreaks, humans can influence the evolution of the virus in different ways.
One important concept in this interaction is the viral charge. This refers to the amount or concentration of a virus present per ml of a body fluid. In the case of SARS-CoV-2, a higher viral load in respiratory secretions increases the risk of transmission through droplets. Viral load relates to the potential to transmit a virus to other people, with viruses like Ebola having an exceptionally high viral load, while the common cold has a low one.
The research group led by Professor Shingo Iwami identified trends using mathematical models with an artificial intelligence component to investigate previously published clinical data. They discovered that SARS-CoV-2 variants that were most successful in spreading had an earlier and higher peak in viral load, as well as a shorter duration of infection. The researchers also found that changes in incubation period and proportion of asymptomatic infections recorded as the virus mutated affected its evolution patterns.
Iwami and his colleagues suggest that human behavior changes designed to limit transmission were increasing selection pressure on SARS-CoV-2, causing it to be transmitted primarily during pre-symptomatic periods when human behavior changed its infectious cycle. As a result, this change advanced peak viral load to occur more effectively at an early stage in pre-symptomatic stages for better transmission rates. Scientists emphasize that when developing public health strategies for Covid-19 and potentially pandemic pathogens in future instances it is necessary to consider how changes in human behavior impact virus evolution patterns.
The study suggests that new coronavirus strains may have evolved due to a complex interaction between clinical symptoms and human behavior.
In conclusion, understanding how human behavior affects virus evolution is crucial for predicting how future pandemics may evolve and develop adaptive treatments and interventions for them.
Overall, these findings highlight the importance of considering human behavior changes when developing public health strategies for infectious diseases like Covid-19.