What's the point of testing critical patients for COVID-19 if no specific treatment exists for the disease?

Question

Given that as of this point of time no specific treatment exists for COVID-19 patients, why are governments primarily spending their testing capacity on those admitted to hospitals or otherwise in critical condition? In theory, anyone showcasing any of the COVID-19 symptoms could be presumed to actually have the disease, but doctors and policy makers seem to think otherwise.

I do understand why testing would be beneficial for asymptomatic/lightly symptomatic patients - knowing they're infected will help them socially isolate for others. But once a patient is in a hospital with breathing difficulties... what good does a test do?

Answer 1

This q is based on fairly incorrect premises e.g.

why are governments primarily spending their testing capacity on those admitted to hospitals or otherwise in critical condition?

[...]

once a patient is in a hospital with breathing difficulties... what good does a test do?

There seems to be a conflation here that "admitted to hospitals" is (nearly) always "in critical condition" and likewise that "with breathing difficulties" somehow also equates "in critical condition" and a Covid-19 diagnosis.

Besides HCW safety, addressed in Dr. Chiu's answer, there's an obvious reason to test someone with "breathing difficulties" (for Covid-19) to establish a differential diagnosis. I think first a diagnosis of what the breathing difficulties actually are is done, e.g. is it pneumonia? Second, the guidelines for further diagnosing the serious cases of pneumonia generally recommend establishing the actual pathogen, e.g.:

Optimal treatment of lung infections relies on rapid and accurate detection of the offending pathogen. Delay in diagnosis can lead to increased morbidity and mortality.

See also Use of antibiotics with chest infections for a bit more detailed discussion on this.

Additionally, early in the epidemic, evidence from China (Mar 4) was that [their] virus tests were actually rather insensitive, i.e. they could only detect high viral loads:

In the initial screening, computed tomography (CT) examination is needed for the auxiliary diagnosis. The diagnosis is then confirmed by the positive results of the nucleic acid amplification test (NAAT) of the respiratory tract or blood specimens using reverse transcription real-time fluorescence polymerase chain reaction (RT-PCR). However, this diagnosis method is highly limited: (1) When the viral load is low, the detection rate is low, leading to false-negative results. (2) Only a positive diagnosis can be made, but the severity of COVID-19 and its progression cannot be judged (in contrast, CT imaging can reveal disease progression). (3) The supply of the reagents cannot keep up with the demand, and the quality of new products of major companies awaits to be studied and improved. (4) It takes 1 day or longer to obtain the results after sampling. For these reasons, Chinese researchers strongly recommend CT imaging as the main basis for the diagnosis of COVID-19 in the current situation.

So in such circumstances (low-sensitivity tests) the virus tests probably aren't even very useful for the mild cases, so "saving" [such insensitive] tests for these mild case is basically completely pointless.

(See also related q here on that latter issue: Why were so many Covid-19 negative tests among close contacts of the early Chinese cases? )

Answer 2

The care for a COVID-19 patient is totally different from that of a patient with other forms of pneumonia. A COVID-19 patient is highly contagious, and is able to aerosolize large amounts of potentially lethal virions into the environment infecting other hospital patients and staff. This happens particularly in intubation. These patients need to be treated in rooms quarantined from other patients, or, shared only with other COVID-19 patients.

The care of a COVID-19 patient also involves the use of PPE. There is a huge shortage of PPE in a large numbers of countries especially in epicentres where people have been resorting to wearing trash bags to help protect them from infection. PPE has traditionally been disposable between patients but the shortage of PPE has meant that it has been reserved just for use when working with patients with known COVID-19, and been reused.

These are three nurses from Northwick Park, London, a centre of clinical excellence.

wearing trash bags as protection, and using surgical masks instead of N95 masks. All three nurses subsequently contracted COVID-19.

Early in the disease in some countries medical staff had to be stood down for self isolation when they had unprotected contact with COVID-19 patients. And estimates range from 20-80% of COVID-19 patients are asymptomatic which means testing needs to be done.

https://www.vice.com/en_us/article/dygbdz/these-nurses-had-to-wear-trash-bags-as-ppe-now-they-have-coronavirus