When should a person with COVID-19 (Coronavirus Disease 2019) be retested?

COVID-19 Retesting Guidelines

For individuals with COVID-19, retesting is generally not recommended routinely, but should be guided by a symptoms-based approach that requires at least 10 days since symptom onset, at least 3 days of being fever-free without antipyretics, and improvement in respiratory symptoms. 1

Symptoms-Based Approach (Preferred)

The Infectious Diseases Society of America (IDSA) recommends a symptoms-based approach over routine retesting for most individuals with COVID-19 1. This approach requires:

• At least 10 days have passed since symptoms first appeared
• At least 3 days (72 hours) have passed since recovery, defined as resolution of fever without the use of fever-reducing medications
• Improvement in respiratory symptoms (e.g., cough, shortness of breath)

This approach is preferred because:

• Repeat SARS-CoV-2 RNA testing within 7 days of a negative test result rarely yields a positive result 1
• PCR tests may remain positive long after a person is no longer infectious, as they detect viral RNA fragments rather than viable virus

Test-Based Approach (Special Circumstances)

In certain situations, a test-based approach may be considered:

• For immunocompromised individuals
• For those in congregate settings where transmission risk is high
• Before restarting immunosuppressive medications
• When required by institutional protocols

The test-based approach requires:

• Meeting all clinical criteria from the symptoms-based approach PLUS
• Two consecutive negative COVID-19 molecular assays (RT-PCR or NAAT) collected ≥24 hours apart 1

Asymptomatic Individuals

For asymptomatic individuals who tested positive for SARS-CoV-2:

• Retesting is not routinely recommended
• They may end isolation after at least 10 days have passed since the date of their first positive test 1
• Testing should be done at least 5 days after exposure for those with known exposure 1, 2

Special Considerations

Timing of Testing After Exposure

• Test at least 5 days after exposure to COVID-19
• If symptoms develop before day 5, test immediately 2

Specimen Collection

• Self-collected specimens (anterior nasal or mid-turbinate) perform similarly to healthcare provider-collected specimens 2
• Saliva specimens have high sensitivity (92%) and may be a good alternative to nasal swabs 2

Common Pitfalls to Avoid

• Relying solely on PCR tests to determine end of isolation period (may remain positive for weeks)
• Testing too early after exposure (before day 5) can lead to false negatives
• Inadequate sample collection can lead to false negatives
• Failing to consider that some individuals may shed viral RNA for extended periods without being infectious

Conclusion

The evidence strongly supports using a symptoms-based approach rather than routine retesting for most individuals with COVID-19. This approach balances the need to prevent transmission while avoiding unnecessary testing and prolonged isolation periods that PCR testing might cause due to persistent detection of non-viable viral fragments.