The US Centres for Disease Control (CDC) is now advising that asymptomatic people should be tested for COVID-19.

The CDC gave the update on Friday 18th Sept and states: "Due to the significance of asymptomatic and pre-symptomatic transmission, this guidance further reinforces the need to test asymptomatic persons, including close contacts of a person with documented SARS-CoV-2 infection."

Last month, the CDC had posted this guidance: “If you have been in close contact (within 6 feet) of a person with a COVID-19 infection for at least 15 minutes but do not have symptoms, you do not necessarily need a test unless you are a vulnerable individual or your health care provider or state or local public health officials recommend you take one.”

The change comes after a peer-reviewed study "SARS-CoV-2 seroprevalence and asymptomatic viral carriage in healthcare workers: a cross-sectional study" found that 2.4% of asymptomatic healthcare workers had tested positive for COVID-19 by RT-PCR. Also, in a CDC report for June-August, COVID-19 incidence was highest in persons aged 20-29, an age group that has a greater chance of being asymptomatic.