Should I get tested after X (fill in the blank)?

Testing and Contact Tracing

A) To test or not to test? When in doubt, test. If testing access is limited, prioritize testing after riskier activities and when you pose a high risk to others. Continue using SMARTS layers of protection on top of testing.

Read on for the TL;DR on when testing adds the most value and how to time it right.


👉 The value of testing after an activity depends on how risky it is. Testing adds a lot of value after a large indoor wedding with iffy mask adherence, and unvaccinated attendees. It adds a lot less value after a short flight with fully masked, vaccinated, pre-tested passengers, on a plane with great HEPA filtration.

🥳 The same type of activity (e.g. weddings, flights, concerts) can carry wildly different risks depending on who was there and which precautions were taken.

✅ To gauge the riskiness of your activities, use our SMARTS checklist. Every layer of protection lowers the risk-o-meter. Every hole in these layers dials up the risk-o-meter – and increases the value of testing:


✔️ Space: Was there at least 6 ft of space between people most of the time?
✔️ Masks: Were masks worn properly at all times?
✔️ Air: Was the air flowing and/or HEPA filtered?
✔️ Restrict: Was attendance restricted to a small number of people?
✔️ Time: Was the activity duration brief?
✔️ Shots: Are you vaccinated? Was everyone else?

🦠 We should also consider how likely it is that someone brought COVID-19 to the party. Testing offers more value in COVID-19 hotspots, and less when local rates are low or when pre-screening was done to weed out infectious people (e.g. by rapid antigen test or PCR).


🕸️ The cost of missing a case of COVID-19 depends on who this case interacts with. The cost is steeper for those who interact with vulnerable or unvaccinated people or have many close contacts. In this context, testing is a great investment, even after moderate risk activities.


⏰ Ideally, test 3-5 days after a potential exposure, and again in a few days to catch “late bloomers”. The timeline from exposure to detection is similar for PCR and rapid antigen tests. See a recent post for more gory details on testing timelines.


🧪 If you are fortunate to have easy access to either PCR or rapid antigen tests, use them liberally. If tests are difficult to access, focus on getting the most bang for your buck – like after that wedding – or before you interact with vulnerable people.

🧀 Since no test is perfect, always use your SMARTS layers to protect others. The more the better!

📣 Great news! Access to rapid antigen tests is about to improve dramatically for Americans. President Biden just announced a $1 billion investment in rapid antigen tests!

➡️ To be clear, this post is about the grey area. If you know you have been exposed or have COVID-19 symptoms, testing is not optional!


Thanks to Dr. Chana Davis of FueledByScience for continuing to tackle thorny questions around testing.

Rapid testing Biden news

DP Links:

Help! I’ve been exposed. When is the best time to test following an exposure?

Should I take a rapid antigen test before…

What to do if you’ve been exposed or have symptoms

Practical testing advice for families

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