With COVID-19 test numbers down, what does the test positivity rate mean?

Amid soaring COVID-19 case numbers fuelled by the highly transmissible Omicron variant, many provinces no longer have the capacity to test everyone who hassymptoms or has been in contact with someone who tested positive.

That's led health officials to warn that the true number of COVID-19 cases in Canada is likely far higher than what is being reported by the provinces and territories.

But another, related statisticcan still reveal some important information;the test positivity rateis the percentage of the total COVID-19 tests performed that produced a positive result.

It's a useful way to understand the level of community transmission.A high test positivity rate even when the overall number of tests done is low shows that there's a high level of community transmission.

But it's important to remember that a test positivity rate of 50 per cent does not mean that half of the population has COVID-19.

On Friday, for example, the tiny Bearskin Lake First Nation in northern Ontario reported a test positivity rate of more than 50 per cent.But the portion of the population that tested positive was just somewhere over 10 per cent.

While the test positivity rate can give someone a good idea about the level of risk in theirarea, it doesn't tell the entire story.

It's important to keep in mind that when a province isn't testing enough people and people aren't seeking out tests,the test positivity rate will not reflect the true picture,just like the case count. The rate also does not include rapid test results,which are normally done by individuals and not reported to officials.

Omicron appears to lead to less severe illness, which means many cases could go untested.So it is important to also look at local hospitalization numbers, ICU capacity and even wastewater testing to get a true sense of the size of the Omicron surge.

Whenthe percentage of cases that are testing positivestarts to level out and come down, that will be the indicator that the Omicron wave has peaked.