BNL-developed model suggests new waves of COVID-19 infection may keep coming

A mathematical model developed by a scientist from the Center for Functional Nanomaterials (CFN) at Brookhaven National Laboratory explains why the COVID-19 pandemic continually experiences new waves of infection -- and suggests COVID-19 may be endemic, sticking around like the flu and the common cold.

The new epidemiological model encompasses the randomness and dynamic variability of individual social interactions, as well as individual differences in the size of social networks. A team of scientists, which includes researchers from the University of California San Diego and the University of Illinois Urbana-Champaign in addition to BNL, reports that this newly accounted-for random dynamic factor will always produce waves or plateaus of infections—like those seen throughout the pandemic—whether or not the model also accounts for individuals’ changing their social behavior based on knowledge of current infection rates. The model further tells us that COVID-19 may be here to stay—it shows a clear path for it to becoming endemic in the global population.

These results are published online in the December 14, 2021 issue of the journal eLife.

The new model builds on the researchers’ prior published work that showed the concept of “herd immunity” does not apply to the COVID-19 pandemic, because this type of collective immunity to the disease turns out to be short-lived. Instead, what emerges is a fragile and temporary state of collective immunity, which they coined "transient collective immunity" (TCI). This earlier work captured individual heterogeneity of both biological and individual social-activity levels in one parameter they called the “immunity factor.”

Lead author Alexei Tkachenko, a physicist in the Theory and Computation Group at the CFN, says the current work resolves some longstanding problems in epidemiological modelling.

“Our new model describes three phenomena: why during a pandemic, a wave stops; how it can progress at a nearly constant rate, forming a plateau; and why new pathogens actually stay with us permanently, entering what’s called an endemic state,” he notes. “This is an old mystery in epidemiology. Classical theory tells us when a new pathogen is introduced, it will eventually kill itself off by infecting enough people that herd immunity is developed, unless biological immunity is very short-lived. But even in the case where long-term biological immunity is developed, we explain the scenario of how a new pathogen stays endemic in a population.”

This research is funded by the DOE Office of Science, University of Illinois System Office, the Office of the Vice-Chancellor for Research and Innovation, the Grainger College of Engineering, and the Department of Physics at the University of Illinois Urbana-Champaign. Brookhaven National Laboratory is supported by the U.S. Department of Energy’s Office of Science.

Read more: https://www.bnl.gov/newsroom/news.php?a=219303

Read the study: https://elifesciences.org/articles/68341