COVID Resources
The content here is meant to help people understand health care and medical issues. Nothing in this content should be considered or used as a substitute for medical advice, diagnosis or treatment, or constitute the practice of any medical or other professional health care advice. You should always talk to your health care provider for diagnosis and treatment.
Interactive COVID diagnostic test calculators*
Chance of Infection with Negative Test
Chance of infection given a negative test at different pretest probabilities.
Chance of Infection with Positive or Negative Test
Chance of infection at different pretest probabilities
Effect of Multiple Tests
(assuming tests are independent)
*see Woloshin, et al., NEJM (2020)
How Consumers Interpret and Act on Results From At-Home COVID-19 Self-test Kits
A Randomized Clinical Trial
JAMA Internal Medicine
2022;182(3):332-341