Experts are expressing concern about the change, noting that people without symptoms are responsible for a large share of transmissions.

The CDC quietly revised its testing guidance this week, and is now saying that close contacts who have been exposed to the coronavirus but are not exhibiting symptoms do not necessarily need a test.
The change is alarming experts who point out that a large share of transmissions occur before individuals develop symptoms. Some individuals infected with the coronavirus never exhibit symptoms, but can still transmit the virus to others, too.
This makes no sense, tweeted Leana Wen, an emergency physician and visiting professor at George Washington Universitys Milken Institute School of Public Health. People without symptoms account for up to 50% of transmission. We need MORE testing, not less, she wrote.
The CDCs new guidance still recommends that vulnerable close contacts get tested after potential exposure, which is defined as being within six feet of an infected person for at least 15 minutes. People who have been exposed but are not exhibiting symptoms may also be asked to get tested by their health-care providers, or state and local officials, the guidance notes.
Elsewhere on the CDCs website, people who have been in close contact with someone who has covid-19 are told to stay home for 14 days and monitor their symptoms, unless they have had covid-19 within the past 3 months.
The revised testing guidance for close contacts without symptoms states that they should strictly adhere to CDC mitigation protocols. However, it does not explicitly spell out the need to self-isolate at home.
Until Monday, the CDC had recommended that all close contacts exposed to the virus get tested. The agency has not explained the thinking behind the change. Adm. Brett Giroir, assistant secretary for health, told NBC News that the guidance has been updated to reflect current evidence and best public health practices.”