The new guidance is based on the results of a new national study led by rearchers at the University of Massachusetts Chan Medical School, focused on 154 people who tested positive for the virus using P.C.R. tests between October 2021 and February 2022.

It found that among symptomatic people, two tests taken 48 hours apart detected 93 percent of infections. But the same testing pattern detected just 63 percent of infections in asymptomatic people.

When people without symptoms took three tests, each two days apart, the tests caught 79 percent of infections.

Key times to get tested:

• If you have symptoms, test immediately.
• If you were exposed to COVID-19 and do not have symptoms, wait at least 5 full days after your exposure before testing. If you test too early, you may be more likely to get an inaccurate result.
• If you are in certain high-risk settings, you may need to test as part of a screening testing program.
• Consider testing before contact with someone at high risk for severe COVID-19, especially if you are in an area with a medium or high COVID-19 Community Level.

Read more at CDC

Read more at The New York Times