Wednesday, January 05, 2022

Why restricting COVID testing is a bad idea

Ontario and several other provinces are deliberately restricting PCR testing of COVID-19 cases to the vulnerable and those who work in high risk settings. They argue that there just isn't enough capacity for more testing, and that, anyway, hospitalizations and ICU numbers are more important indicators of the progress of the pandemic.

Even Chief Public Health Officer Dr. Teresa Tam has argued that it is not necessary to test all cases, and that enough testing is happening to enable the identification of trends and waves. She also argued that other methods of detection are also taking place, like the testing of municipal waste water, in the absence of robust case testing.

Well, she's the Chief Public Health Officer and I'm not, but I beg to differ. It seems to me that, if testing is constrained to the current level of 140,000-150,000 per days, rather we really won't know whether there are 30,000 new cases a day, or 50,000, or 150,000. If testing is reduced, then new cases will also fall, as sure as night follows day. For example, the province of Ontario alone supposedly has capacity to process 100,000 PCR tests a day, but it's actual processing has gone down from 75,000 at the end of December 2021, to 60,000, then 50,000, to little more than 45,000, all due to a deliberate government policy. And, guess what, new cases reported have also  fallen! When Donald Trump suggested reducing testing back in 2020, people were bemused and outraged, but that is exactly what we are doing right now here in Canada.

New cases today translates into potential hospitalizations next week, so surely it is essential that the health authorities know about case spikes as soon as possible. New cases are the main metric we have used all the way through this pandemic, and the one that most lay people are most familiar with. They are all we have to give context to the progress of the pandemic, and to compare our "performance" with other countries and with the past. Also, if the official statistics erroneously show new cases plateauing or even falling, I worry that people will become complaisant and let up on their mask-wearing, distancing and general common sense, and that they will be even less compliant with any future emergency public health measures that may have to be announced. At any rate, we will not have a reliable comparative handle on just how bad things are.

It's not like we can just use rapid antigen tests instead, as they are in my huge demand and impossible to obtain (either the free government-issue ones, or even commercial ones). They are notoriously inaccurate compared to PCR tests, particularly for the Omicron variant, and many false negatives will still pass through the net (as well as a few false positives, take the case of Maple Leafs star Auston Matthews, for example). Hell, it even depends on what time of day you do the test, with midday tests being twice as accurate as evening tests according to one study! And if no-one is keeping records on them, what use are they for public health planning?

Another good reason to keep up PCR testing is that, although rapid antigen tests are good for roughly establishing whether a person is likely to be infectious at a point in time (and therefore have a valid function in the mix of public health measures), PCR tests are needed to definitively register a case, so that otnshows up in statistics (which are another valid element of public health measures) and, also importantly, to analyse which variant the case is.

And, last but by no means least, keeping track of cases IS important, even if the illnesses the Omicron variant generates are relatively mild compared to earlier variants (maybe). They are important because the pandemic won't be over until new cases are reduced to a consistent and manageable level. Until then, we will be just lurching from one crisis to another, wading through one wave and then the next. Waste water testing is simply no substitute for this. Plus, don't forget, the more cases there are spreading in the wild, the greater the possibility of new variants arising (every new infection provides a chance for the virus to mutate). Do we really want this thing to go on forever?

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