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Why do patients (and even HCPs) take on medical risks they don't need to? Behavioral science explains.

A behavioral science analysis of how Risk Compensation heuristic gave many patients a false sense of security from natural immunity to COVID-19.
ImageNewristics Image18 July 2022

How perceived immunity can make us irrationally risky

People show valid concerns over how long immunity to COVID-19 lasts after infection or vaccination. A typical worry may be that post-infection/vaccination COVID-19 immunity is not good enough to stop worrying about re-infection. The concern may lead to continued risk-averse behavior. Pessimism about immunity could motivate people to continue social distancing and follow hygiene protocols.

On the flip side, optimism about being less at-risk after getting COVID-19 can trigger Risk Compensation - a tendency to increase risk-taking behavior after feeling safer. People may go out and be lax about social distancing or spend more time in a restaurant with unknown people if they believe they can “afford” it because they have either contracted the disease or been vaccinated. Perceived immunity could become a decision-criteria to engage in risk-taking behavior, that may lead to problems like infecting others, catching different diseases, splurging money, and motivating others to take risks.

Perception of immunity can foster well-being-promoting risk-averse behavior or even health-compromising risk-taking behavior.

Without a vaccine, what do we know about the duration of immunity against COVID-19?


A study assessed 254 blood samples from 188 infected patients with a follow-up on 43 samples after 6 months. The researchers evaluated the adaptive immune system’s main components like T-cells, IgG antibodies, and memory B cells to estimate how long immunity to sars-cov-2 lasts.

They found that people are likely to stay immune for 6-8 months after infection. Their data does not conclude if and when a person could become asymptomatically infectious again.

Those 6-8 months can be a time for Risk Compensation. People would likely display behavior that they’ve rationalized and deemed acceptable after assessing other local factors.

Information about the local spread feeds Risk Compensation

The severity of COVID-19 has been dramatically different across populations. Countries differ in their:

  • Death rates
  • Rate of infection
  • Severity of infection
  • Presumed immunity
  • Volume of asymptomatic cases
  • Rigor in testing and test-result reporting
  • Public health measures
  • Patient discharge criteria
  • Density and frequency of essential and non-essential social contact
  • Individual conformity to safety rules.

All these factors influence the local spread, as well as the nature of concerns people have regarding immunity. Knowledge of local transmission appears to be practically more relevant for individual-level decision-making regarding social movement, motivation to vaccinate, motivation to adhere to precautions, etc. After assessing these factors, a person may inaccurately pass judgment on subjective risks and engage in behavior they feel is justified. For example, they may think - “It’s ok to not sanitize my delivery packages because I may have antibodies” or “I will be fine if I visit my friends who are coughing because I am immune.”

One can’t be certain about long-term immunity against the virus’s emerging mutations when one isn’t vaccinated. Until a whole community gets vaccinated, people will likely try to manage their risks in ways they believe are acceptable. So how can we safeguard ourselves from unwanted risks that emerge through Risk Compensation?

The conclusion is simple. Instead of assuming 100% immunity that rationalizes risk-taking behavior, people should continue following the easy safety protocols such as social distancing and using proper masks. Social distancing, wearing a mask, and using disinfectants can help counter risk-taking behavior when people unconsciously display the Risk Compensation behavioral pattern.


  • Dan, J., Mateus, J., Kato, Y., Hastie, K., Yu, E., & Faliti, C. et al. (2021). Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection. Science, 371(6529).
  • Trogen, B., & Caplan, A. (2021). Risk Compensation and COVID-19 Vaccines. Annals Of Internal Medicine.