What are your thoughts about testing following high risk travel? Should testing be done within 72h of travel or should that employee wait 5 days after his/her travel?

The best response to this question is that “it depends”.  From the question, I assume an employer or consultant is considering using a test to modify a recommended duration of quarantine after a high-risk exposure, such as travel, in an asymptomatic individual.  

With the assumption above, and taking when to test out of the picture,  my advice for travel within the US is to first review local requirements or recommendations, as many US states or cities require/recommend quarantine for travelers from certain locations.  If local requirements/recommendations alone are not an issue, then some international travel, type of travel, or activities in which the individual participated, might be identified as high risk, warranting quarantine, staying home as much as possible while ensuring wearing a face covering and physical distancing.  The CDC lists the following as high risk travel related activities.  
  • Being in an area that is experiencing high levels of COVID-19, including destinations with a Level 3 Travel Health Notice. You can check the Travel Health Notices for recommendations for places you have traveled, including foreign countries and U.S. territories.  You can also check states, counties, and cities to determine if these areas are experiencing high levels of COVID-19.
  • Going to a large social gathering like a wedding, funeral, or party.
  • Attending a mass gathering like a sporting event, concert, or parade.
  • Being in crowds – for example, in restaurants, bars, airports, bus and train stations, or movie theaters.
  • Traveling on a cruise ship or river boat.”1, 2 

If the employee in question is considered a critical or essential employee, following the CDC recommendations for serial testing might be an option3 or other recommendations to limit risk of transmission of the virus4

In general, use of a single test (not serial testing) in an asymptomatic individual to evaluate quarantine duration, is only useful if positive.  In that situation, you know the individual’s status and contact tracing can be initiated.  The results of a single test, if negative, cannot appropriately be used to justify shortening the duration of a quarantine period. The positive predictive value and negative predictive value of any single test, false negative and false positives rates depend on the type of testing used, prevalence of  COVID-19, and timing of the test in relation to when the exposure occurred and the clinical status of the patient. An OEM provider could help assess some of these factors and interpret the results for a particular patient or help design an appropriate workplace policy.  

There may be situations after travel where serial testing is reasonable such as mentioned above.   

Whether and when to begin testing after a return from high risk travel (or activity) would depend on many factors; whether the individual is symptomatic or asymptomatic, the purpose of testing, whether the individual is critical or essential, the actual type of test (molecular (PCR), antibody or antigen) and even the specific brand of test being utilized. The purpose of testing and need for accuracy should drive the test selected and will also be affected by the prevalence of the infection in the community.  When considering which day to test, you need to determine which day should be considered day 1, the day last potentially exposed (returned from high risk travel) or the day of likely exposure from another high-risk activity.  

For more information on the use of serial testing, see ACOEM COVID-19 Forum question G2 - Can you comment on the COVID PCR monitoring program at Amazon or other similar large companies? Should workers be tested randomly or is there an epidemiologic formula to ensure the proper sample size and frequency of testing?


  1. CDC. Coronavirus Disease 2019 (COVID-19): Travel during the COVID-19 Pandemic https://www.cdc.gov/coronavirus/2019-ncov/travelers/travel-during-covid19.htm
  2. CDC. Coronavirus Disease 2019 (COVID-19): After You Travel https://www.cdc.gov/coronavirus/2019-ncov/travelers/after-travel-precautions.html
  3. CDC. Coronavirus Disease 2019 (COVID-19): Testing Strategy for Coronavirus (COVID-19) in High-Density Critical Infrastructure Workplaces after a COVID-19 Case Is Identified https://www.cdc.gov/coronavirus/2019-ncov/community/worker-safety-support/hd-testing.html
  4. CDC. Coronavirus Disease 2019 (COVID-19): Implementing Safety Practices for Critical Infrastructure Workers Who May Have Had Exposure to a Person with Suspected or Confirmed COVID-19, https://www.cdc.gov/coronavirus/2019-ncov/community/critical-workers/implementing-safety-practices.html

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The Forum does not necessarily represent an official ACOEM position. The Forum is intended for health professionals and is not intended to provide medical or legal advice, including illness prevention, diagnosis or treatment, or regulatory compliance. Such advice should be obtained directly from a physician and/or attorney. Questions are answered with the best available data or recommendations at the time.