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Why People Lie About Being Sick: 5 New Scientific Facts

A new study investigated why people conceal an infectious disease.

Key points

  • About 75% of people sometimes conceal that they have an infection.
  • Common reasons for concealing an infection are prioritizing own needs and work or study issue.
  • People are more likely to lie about low-risk infections than about high-risk infections.

People lie about being sick

Sometimes, we catch an infection at an inconvenient time: Just before a super important work meeting, an eagerly awaited first date, or a good friend’s wedding. However, going to an event with an infectious disease can have many negative social consequences. For example, the other guests at a wedding may think that a person who constantly sneezes and coughs may be egoistic and irresponsible since they risk infecting other guests.

This is why many people who attend social gatherings knowing that they are having an infection lie about being sick and try to conceal their infection. This may go from simply neglecting to tell other people about a slight fever to actively lying, such as mentioning that sneezing is due to an allergy, not an infection (and therefore there is no danger of infection for other people).

Unfortunately, concealing an infection can have severe consequences for other people, such as those with immune disorders or a vulnerable older person.

A new study on the psychology of concealing an infection

Despite its high relevance for the transmission of infectious diseases, not much is known about the psychology of why and when people lie about having an infection. Therefore, a new scientific study, now published in the prestigious journal Psychological Science (Merrell and colleagues, 2024), focused on answering these questions.

The study, first authored by scientist Wilson N. Merrell from the Department of Psychology at the University of Michigan, consisted of 10 different experiments in which concealing an infection was investigated in various groups of people such as students, healthcare employees, and workers. More than 4000 volunteers provided data for the study, making the results very robust and trustworthy.

Here are the 5 main scientific insights from the study:

1. About 75% of people conceal infections

The percentage of people who admitted to at least sometimes concealing an infection was surprisingly high: Across the 10 experiments in the study, the percentage was between 53% (healthy people who projected concealing an infection in the future) to 85% (university students). The average percentage was around 75% So three out of four people sometimes conceal that they are sick when meeting with others.

2. There are two ways of concealing an infection

The scientists found two main ways of concealing an infection in the data. First, there were so-called omissions (e.g., simply not mentioning the topic of infection and pretending everything was OK). Second, there were so-called commissions (e.g., actively covering up symptoms of the infection and lying about them). Both types of concealment were common.

3. There are four main psychological motivations for concealing an infection

The scientists identified four main psychological motivations for why people conceal an infection. The two most common ones were “prioritizing the self” (reported by 46% of volunteers) and “school or work issues” (also reported by 46% of volunteers). “Prioritizing the self” included motivations such as not wanting to cancel an appointment for which one waited for a long time. “School or work issues” included things like not wanting to miss class shortly before the finals to avoid negative consequences on school marks. The other two less common psychological motivations to conceal an infection were “Prioritizing others” (e.g., not wanting other people to worry) and “policy requirements” (e.g., not having many sick days as a new employee and being afraid of getting fired).

4. People more commonly lie about low-risk infections

Depending on their type, infections can be fairly low risk for most other people (e.g., the common cold) or have severe consequences such as death or lifelong impairment. In one experiment, volunteers were asked to imagine concealing infections with low, middle, or high risk for other people. The results showed that people are more likely to conceal low-risk, mild infections than awful ones. However, the duration of the illness did not affect the percentage of concealment.

5. People who are sick at the moment they are asked about concealing an infection report more concealment than healthy people imagining being sick

There was a statistically significant difference between people who were sick when asked about concealing sickness and people who merely imagined a sickness. Overall, sick people reported more concealment of infections than healthy people. Thus, health status affects how often people lie about being sick.


Merrell, W. N., Choi, S., & Ackerman, J. M. (2024). When and Why People Conceal Infectious Disease. Psychological science, 9567976231221990. Advance online publication.

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