The ideal time to get tested for COVID-19 is 6-7 days after exposure. That is because it takes about 6 days for the virus to multiply enough to cause an infection and be found on a test.
You may have potentially been exposed many times. For example, on a recent trip you could have been exposed in the airport or on the plane in flight, during your stay, and in the airport or plane coming back. So the right time for testing is 6-7 days back from arrival to check for an asymptomatic infection. If you are living with a person diagnosed with COVID-19, you can get tested 5 – 6 days after they developed symptoms or were diagnosed if they are asymptomatic.
Of course, if anyone gets symptoms they can get tested right away.
The test I can run in my office is an antigen test and not ideal for asymptomatic people. It will find only 80% of asymptomatic infections. The test is much better used for finding infections in people who have symptom – 97% in that case which is in line with PCR testing.
PCR testing is the ideal for finding asymptomatic infections…if checked at the proper time. Again, that means waiting at least 6 to 7 days after exposure. That is because the mean (average) time it takes to get infection is 6 days but it can range from 1 to 14 days. Checking the test on day 6 after exposure will catch the average case (most cases) but will miss infections that occur after day 6.
If you were exposed to COVID-19, you are now in quarantine. A 14-day quarantine carries only a slight risk of transmission – 0.1% – after quarantine. By comparison, after a shorter 10-day quarantine without testing, the transmission risk is higher, ranging from 1% to 10%.
After the shortest 7-day quarantine with a negative PCR test at 6 to 7 days, the risk of transmission is estimated to be about 5% to 12%.
So you may want to quarantine longer based on the risk of those around you.
Here are some locations for quicker turnaround PCR tests: