A new study by a team from Nagoya University (Japan) has shed light on how human behavior affects the evolution of new strains of SARS-CoV-2, the virus that causes Covid-19. The researchers found that confinements and isolation measures can alter the evolution of the virus in different ways, making it more transmissible earlier in its life cycle.
The study, published in Nature Communications, provides valuable insights into the relationship between people’s behavior and disease-causing agents. By isolating sick people and using lockdowns to control outbreaks, humans can influence the evolution of the virus in various ways, predicting how these changes occur is crucial for developing adaptive treatments and interventions.
One critical concept in this interaction is viral charge, which 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 common colds have 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. Additionally, they found that decreased incubation periods and increased proportions of asymptomatic infections recorded as the virus mutated affected its evolution as well.
Iwami and his colleagues suggest that human behavior changes designed to limit transmission exerted selection pressure on the virus. This caused SARS-CoV-2 to be transmitted primarily during pre-symptomatic stages before it developed symptoms. As a result, peak viral loads advanced earlier to spread more effectively during those initial stages. The study suggests that when evaluating public health strategies for responding to Covid-19 and potentially pandemic-causing pathogens in the future, it is essential to consider how changes in human behavior impact virus evolution patterns.
Overall, this research highlights how important it is to understand how our actions impact disease progression and development of new strains. By taking proactive measures like social distancing and quarantine protocols early on could significantly reduce transmission rates and ultimately save lives