How Fears (of COVID and Vaccines) Influence Coronavirus Transmission

New mathematical model involves human behavior — and the fears it causes — to better predict multiple waves of infections.

A new mathematical model for predicting infectious disease outbreaks involves fear — both for disease and vaccines — to better understand how pandemics can occur across multiple waves of infection, like the one we see with COVID-19. The “Triple Contagion” model of illness and fear, developed by researchers at the NYU School of Global Public Health, is published in the Journal of The Royal Society Interface.

Human behaviors such as social distancing (which suppresses the spread) and vaccine refusal (which promotes it) have shaped the dynamics of epidemics for centuries. Yet traditional epidemic models have largely ignored human behavior and the fears it causes.

“Emotions such as fear can negate rational behavior and lead to unconstructive behavior change,” said Joshua Epstein, a professor of epidemiology at the NYU School of Global Public Health, founder and director of the NYU Agent-Based Modeling Laboratory, and lead author of the study. “Fear of a contagious disease can change the behavior of sensitive individuals; they can take action to protect themselves, but give up on those actions prematurely when the fear subsides.”

For example, the fear of contracting a virus like SARS-CoV-2 can cause healthy people to isolate themselves at home or wear masks, suppressing the spread. But as the spread is reduced, the fear can evaporate, causing people to stop isolating or wearing masks too soon, while many infected people are still around. This pours fuel – in the form of sensitive people – onto the embers and another wave explodes.

Likewise, fear of COVID-19 has motivated millions of people to get vaccinated. But because vaccines suppress the spread and thus the fear of disease, people may fear the vaccine more than the infection and forego vaccination, causing the disease to resurface.

For the first time, the “Triple Contagion” model links these psychological dynamics to disease dynamics, uncovering new behavioral mechanisms for pandemic persistence and successive waves of infection.

“If the fear of COVID-19 outweighs the fear of the vaccine, it could boost vaccination and therefore suppress the virus, a trend we saw in the US this spring as millions of Americans were vaccinated and cases dropped,” Epstein said. .

“But if people think the vaccine is scarier than the disease — whether they’re skeptical about the seriousness of COVID-19 or because of unfounded fear of the vaccine fueled by misinformation — our model shows that people avoid vaccines and there are a new disease cycle can arise. . We see this happening in real time in regions with lower vaccination rates, where the Delta variant is spreading rapidly and the number of cases is increasing,” Epstein added.

The mathematical model developed by Epstein and his colleagues takes into account behavioral factors — such as the proportion of the population who fear the disease or the vaccine, and how side effects of vaccinations can cause anxiety — in addition to factoring in speed. of disease transmission, the percentage of the population that is vaccinated and the level of vaccination. In addition, the model recognizes that fear is not static: it can spread through a population as a result of misinformation or alarming updates, or fade with time or comforting news.

“Neuroscience suggests that anxiety itself may be contagious, but anxiety also tends to fade or wane. In our model, people can overcome their fear of disease and vaccines — either over time, when disease prevalence declines, or through interactions with others who recovered from COVID or received the vaccine and had minimal side effects,” Epstein said.

The model illustrates that the two fears evolve and interact in ways that shape social distancing, vaccine uptake, and easing of these behaviors. These dynamics, in turn, can amplify or suppress disease transmission, which feeds back to influence behavior, causing disease resurgence and multiple waves.

“Our ‘Triple Contagion’ model leverages the neuroscience of fear learning, extinction and transmission to reveal new mechanisms for multiple pandemic waves of the kind we see in the current SARS-CoV-2 pandemic and new ways to think about reducing its spread,” said Erez Hatna, a clinical associate professor of epidemiology at the NYU School of Global Public Health and a co-author of the study.

Reference: “Triple Contamination: An Epidemic Model with Two Fears” by Joshua M. Epstein, Erez Hatna, and Jennifer Crodelle, Aug. 4, 2021, Journal of The Royal Society Interface.
DOI: 10.1098 / rsif.2021.0186

In addition to Epstein and Hatna, Jennifer Crodelle of Middlebury College is a study author. The research was funded by the National Science Foundation’s Collaborative Research: RAPID: Behavioral Epidemic Modeling For COVID-19 Containment (grant number 2034022) and a New York University COVID-19 Research Catalyst grant.