Summary: A research group at Nagoya University, using AI and mathematical modeling, has uncovered that human responses to COVID-19, such as lockdowns and isolation, have influenced the evolution of the virus. The study found that SARS-CoV-2 variants became more transmissible early in infection due to these interventions, demonstrating a complex relationship between viral load, transmission dynamics, and human behavior. As the virus evolved from the Wuhan to the Delta strain, it exhibited a significant increase in maximum viral load and a quicker peak. This highlights the importance of considering human behavior in public health strategies and virus evolution studies.
Key Facts:
- Human responses, like isolation and lockdowns, impacted the evolution of the virus and made it more transmissible early in infection.
- The study revealed a 5-fold increase in maximum viral load and a faster peak as the virus evolved from the Wuhan to Delta variants.
- This research emphasizes the need to integrate human behavior into understanding virus evolution and developing adaptive public health strategies.
Source: Nagoya University
Using artificial intelligence technology and mathematical modeling, a research group led by Nagoya University has found that human behavior, such as lockdowns and isolation measures, influence the evolution of new strains of COVID-19. SARS-CoV-2 developed to become more transmissible earlier in its lifecycle.
The team’s findings, published in Nature Communications, offer new insights into the connection between human behavior and disease-causing agents.
As with any other living organism, viruses evolve over time. Those with survival advantages become dominant in the gene pool. Many environmental factors influence this evolution, including human behavior.
By isolating sick individuals and implementing lockdowns, humans might complicate virus evolution. Understanding how these changes occur is crucial for developing adaptive treatments and interventions.
An important concept in this interaction is viral load, referring to the concentration of a virus in bodily fluids. In SARS-CoV-2, a higher viral load increases the risk of transmission through droplets. Viral load is linked to a virus’s potential to transmit to others.
The research group, led by Professor Shingo Iwami at the Nagoya University Graduate School of Science, identified trends using mathematical modeling with an artificial intelligence component to analyze previously published clinical data. They found that the most successful SARS-CoV-2 variants had an earlier and higher peak in viral load.
However, as the virus evolved from the pre-Alpha to Delta variants, it had a shorter duration of infection. The researchers also found that changes in the incubation period and the increased proportion of asymptomatic infections recorded as the virus mutated also affected its evolution.
The results showed a clear difference. As the virus evolved from the Wuhan strain to the Delta strain, they found a 5-fold increase in the maximum viral load and a 1.5-fold increase in the number of days before the viral load peaked.
Iwami and his colleagues suggest that changes in human behavior to limit transmission were increasing the selection pressure on the virus, leading to it being transmitted mainly during the asymptomatic and presymptomatic periods. As a result, the viral load peak advanced to this period.
When evaluating public health strategies in response to COVID-19 and any future potentially pandemic-causing pathogens, it is necessary to consider the impact of changes in human behavior on virus evolution patterns.
“We expect that immune pressure from vaccinations and/or previous infections drives the evolution of SARS-CoV-2,” Iwami said.
“However, our study found that human behavior can also contribute to the virus’s evolution in a more complicated manner, suggesting the need to reevaluate virus evolution.”
The study suggests the possibility that new strains of coronavirus evolved because of a complex interaction between clinical symptoms and human behavior. The team hopes that their research will speed up the establishment of testing regimes for adaptive treatment, effective screening, and isolation strategies.
About this behavioral neuroscience and COVID-19 research news
Author: Matthew Coslett
Source: Nagoya University
Contact: Matthew Coslett – Nagoya University
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Isolation may select for earlier and higher peak viral load but shorter duration in SARS-CoV-2 evolution” by Shingo Iwami et al. Nature Communications
Abstract
Isolation may select for earlier and higher peak viral load but shorter duration in SARS-CoV-2 evolution
During the COVID-19 pandemic, human behavior change as a result of nonpharmaceutical interventions such as isolation may have induced directional selection for viral evolution.
By combining previously published empirical clinical data analysis and multi-level mathematical modeling, it was found that the SARS-CoV-2 variants selected for as the virus evolved from the pre-Alpha to the Delta variant had earlier and higher peak in viral load dynamics but a shorter duration of infection.
Selection for increased transmissibility shapes the viral load dynamics, and the isolation measure is likely to be a driver of these evolutionary transitions.
In addition, it is shown that a decreased incubation period and an increased proportion of asymptomatic infection are also positively selected for as SARS-CoV-2 mutated to adapt to human behavior (i.e., Omicron variants).
The quantitative information and predictions presented here can guide future responses in the potential arms race between pandemic interventions and viral evolution.
