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Contagion: Most people would conceal an infectious illness in public

In a series of studies conducted by the University of Michigan, researchers have uncovered a troubling trend: a significant number of people conceal their infectious illnesses to maintain their work, travel, and social engagements. 

This comprehensive investigation explores the motivations, implications, and potential solutions to this public health concern. The research, led by doctoral candidate Wilson N. Merrell, involved a broad range of participants, including both healthy and sick adults. 

Shocking extent of concealment 

Overall, a striking 75% of the 4,110 participants have either concealed an infectious illness in the past or admitted they would consider doing so in the future. Many participants reported boarding airplanes, going on dates, and engaging in other social interactions while hiding that they were sick. 

Alarmingly, over 61% of healthcare workers participating in the study also reported hiding their infectious conditions. This finding is particularly concerning given the critical role of healthcare professionals in preventing the spread of illness.

Deceptive behavior 

Merrell said that the researchers found a difference between how people believe they would act when ill and how they actually behave.

“Healthy people forecasted that they would be unlikely to hide harmful illnesses – those that spread easily and have severe symptoms – but actively sick people reported high levels of concealment regardless of how harmful their illness was to others,” said Merrell.                

Shocking results

The first study involved 399 university healthcare employees and 505 students. This study started in March 2020, coinciding with the onset of the COVID-19 pandemic. 

The participants detailed their symptomatic days and their frequency of symptom concealment. The individuals then rated how often they actively covered up symptoms from others, came to campus or work without telling others they were feeling ill, or falsified mandatory symptom screeners that the university had required for anyone using campus facilities.

More than 70% of the participants reported covering up their symptoms. Many said they hid their illness because it would conflict with social plans, while a few people said they felt pressure due to institutional policies, such as a lack of paid time off. Only five participants admitted to hiding a COVID-19 infection.

Low symptom severity 

For the second study, 946 online participants were randomly assigned to one of nine conditions in which they imagined being either moderately or severely sick while in a social situation. In each condition, the risk of spreading the illness was designated as low, medium, or high. 

The study revealed that the participants were much more likely to conceal their illness when symptom severity was low and they were less likely to be contagious.

Sick people may be more insensitive 

In a third study, 900 people – including some who were actively sick – were asked to rate the likelihood of covering up an illness in a hypothetical meeting with another person.

The results showed that individuals who were actually sick were more likely to conceal their illness, regardless of its transmissibility.  

“This suggests that sick people and healthy people evaluate the consequences of concealment in different ways, with sick people being relatively insensitive to how spreadable and severe their illness may be for others.”

Public health implications 

Merrell added that the COVID-19 crisis may have shaped the way the participants thought about concealing an illness. He said that future research could explore how ecological factors and medical advances such as vaccines influence people’s disease-related behavior. 

The research team plans to expand this research to other countries to uncover potential cultural differences in concealment behaviors. Merrell noted that the findings carry significant public health implications, illuminating the motivations and tradeoffs we make in social interactions when we’re sick.

“After all, people tend to react negatively to, find less attractive, and steer clear of people who are sick with infectious illness,” said Merrell. “It therefore makes sense that we may take steps to cover up our sickness in social situations. This suggests that solutions to the problem of disease concealment may need to rely on more than just individual good will.”

The study is published in the journal Psychological Science

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