"What Tests Can - and Cannot - Do" I'm Beginning To Read More About The Problem Of False Negatives In Testing For Covid-19 And The Danger Of A False Sense Of Security In Even Real Negative Results

Here's an article by the former head of the CDC,  Dr. Tom Frieden, that starts out with something I've been wondering about, how many false-negatives the Trump regime developed test might have. 

There is understandable frustration and outrage that testing has been slow and often inaccessible in the US. But lack of testing has led some to miss the point of what tests can — and cannot — do.

A surge in people being tested could actually spread disease, because people can become infected by someone else waiting to be tested. Getting tested today is no guarantee you won’t get infected tomorrow — and may give you a false sense of security. Furthermore, emerging data suggests that testing of throat swabs may miss as many as two-thirds of infections.

From my point of view as an infectious disease control physician, it’s dismaying to see both the promises of and demands for widespread testing that, if met, will do little good and possibly some harm. That said, in some contexts testing is absolutely, crucially important:

- In areas with few or no cases, to inform containment and isolation strategies and facilitate contact tracing. Seattle would likely have had a much smaller outbreak if testing there had been widely available sooner.

- In areas with community transmission, to inform treatment and protection of vulnerable groups, especially when there are outbreaks in hospitals, nursing homes, homeless shelters, and prisons.

-  In health care facilities treating severely ill patients, to identify those with Covid-19 in order to improve infection control, know when it is safe to discharge patients, and identify participants in clinical trials. For these reasons, every patient in the United States with severe pneumonia should be tested for SARS-Cov-2 infection.

For epidemiological investigations, to determine how widespread infection is, facilitate surveillance, and inform situational analysis, projections, and investigations, including into how the virus is spreading and how infectious asymptomatic people are. The Centers for Disease Control and Prevention’s initiative of testing for the virus in all patients with influenza-like illness at outpatient health care providers is essential to help understand where the virus is spreading, to whom, and what the trend will be in the coming weeks and months.

In areas where the virus is spreading, there is little benefit, and some potential harm, to testing individuals with mild or no symptoms. In the process of getting tested, these people will take up the time, protective equipment, and lab materials of health facilities. If they’re not infected when they travel to and get care, they may get infected in the process.

This is less of a concern for parking-lot, drive-through testing in the private sector, but whether people with symptoms are positive or not, they must isolate themselves, especially from medically vulnerable people: The test could be falsely negative, or could become positive the next day. Furthermore, in a community-wide outbreak, there’s no way public health workers will be able to identify and track contacts of all people who test positive.