COVID-19: To test or not to test?

Since March 2020, most places in the world have been through several versions of CoVID-19 lockdown. The most extreme level, currently in force in several cities in the USA, prohibits social contact beyond the immediate household throughout the rest of the year. Those who can work from home are expected to do so. Those who cannot must wear a mask at all times outside their residence. 

People who test positive are in for a rough ride – and not just from the illness. 

This latest iteration has forced those of us who provide first line healthcare in the community to assess how to provide testing services that are safe for patients, providers, other staff, and the surrounding communities. Issues such as: where to provide COVID-19 testing, to whom and how often are under revision in real time as the pandemic reaches another peak. 

To date, the solution of “where” has been to isolate testing sites, for example, placing them outside the institutions in car parks and other open air locations. However, recent evidence from the spread of COVID-19 through outside restaurant locations suggests that just being in fresh air is insufficient to stop the spread. Anecdotal evidence suggests that viral load can accumulate in the air around areas of de-masking and may precipitate transmission to and from passers-by and staff, especially in high population density areas such as inner city locations and car parks. 

The solution of “to whom” is also complex. The false negative rate of testing appears to be increasing. That may be due to inadequate nasal swabbing (likely to increase with the home testing about to be introduced as an effective swab is more than just uncomfortable to the nasal passage), or not catching the virus at its peak shedding, or even COVID-19 anxiety leading to multiple testing of the worried well. Repeat testers have twice the false negative rate as patients tested once.

On a more technical note, the surge in testing is resulting in supply chain issues and competition for swab use.  For example, some cities are experiencing a shortage of swabs for other testing, such as sexually transmitted infections. Recommendations of screening local populations do not take into account the supplies of swabs, capacity of testing facilities and cold chain maintenance for samples that would be required.  One projection estimates that to weekly test a population of 200,000 people with 90% compliance, 26,000 tests would need to be carried out per day. 

So far, no community has consistently reached these numbers. 

Retesting is also problematic. For example, re-certifying workers as cleared for work, a task often left to primary care providers, is an issue. Whilst the sensitivity and specificity of initial testing is well established, re-test reliability has not been established and reinfection has been proven to occur. It is too early to tell what stigma will be attached to those who have tested positive and want to return to work and socialize. If the previous century responses to infectious diseases are any indication, people who test positive are in for a rough ride – and not just from the illness.

5 thoughts on “COVID-19: To test or not to test?

  1. Very interesting article professor. In terms of home testing do you think will it be a free system or will the household user have to pay a certain amount per test? Could people buy multiple tests at once or is there a special way to store them? For example at sub zero degrees. Thank you!

    Like

  2. A really thoughtful and considered article about the insistence to test test and retest. Clinicians are able to diagnose Covid in many cases without the “proof” of a test. Is it time to rethink the testing merry go round?

    Like

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