OTTAWA -- The number of known COVID-19 cases in Ottawa is at its lowest level since the start of the first wave, bucking a particular trend that had repeated itself throughout the pandemic.

Cases of COVID-19 tend to rise and fall in "waves", with distinct high points (crests) and low points (troughs).

While much of the reporting around COVID-19 trends in Canada has referred to the most recent wave this past spring as the third, in Ottawa, there have been five distinct waves since the pandemic began; the most recent one crested in April.

Dr. Vera Etches, Ottawa's medical officer of health, has referred to Ottawa's local waves in a similar fashion in the past, noting that we've had more than three, based on recorded trends.

One of the common trends is that after every crest, the trough on the other side is a little bit higher. The number of known active COVID-19 cases has a "floor" that rises after each wave, which suggests there's a larger amount of COVID-19 in the community that doesn't go away.

However, that trend was broken following the most recent wave.

Ottawa's five waves

Data from Ottawa Public Health show five periods where cases crested and fell since the pandemic began.

The first occurred between March and July 2020, with the crest in late April and the trough in late June and early July.

After that, cases rose a bit following Canada Day but were quickly stamped down. The second wave was minor, but there was a distinct crest in late July with a trough in mid-August.

Ottawa's third wave crested in early October, shortly after schools reopened, and fell to a trough in late November.

The post-Christmas wave, Ottawa's fourth, crested in mid-January 2021, and hit a trough in early February.

Then came the fifth and most recent wave, which peaked in mid-April. Case counts continue to decline and Ottawa has yet to see a distinct trough since a new wave has not yet started.


Rising troughs

Each time a wave crests and troughs in Ottawa, the following trough ends up higher.

Following the first wave, which crested 780 known active cases on April 28, the trough fell to 66 active cases on July 2. The next crest was 340 active cases on July 27, which wasn't as high as the first crest, but the trough following it was 158 active cases on Aug. 16, more than double the previous trough, and it never fell below that.

Active cases crested again at 1,501 on Oct. 3, but the following trough never fell below 467 active cases on Nov. 23, seven times higher than the first trough.

The next crest was 1,745 active cases on Jan. 12, 2021, but the clampdown was quick, with a stay-at-home order in place and, by Feb. 8, active cases were back down to 558.

Active cases last crested at 3,804 on Apr. 16. Since then, the number of active cases has been steadily dropping. As of Tuesday, there were 42 active cases, below all of the previous troughs since the start of the pandemic.

The vaccine difference


One of the major differences between the most recent wave and the previous waves is the widespread availability of COVID-19 vaccines.

As of Monday, 70 per cent of the population of Ottawa had received at least one dose of a COVID-19 vaccine and 36 per cent were fully immunized.

Evidence has suggested that a single dose is still effective at preventing serious illness from COVID-19, with the second providing increased immunization.

Etches said in June she does not believe Ottawa will see another lockdown.

"I would be surprised if we had to go that far backwards. I don't see that in the modelling and the projections from the science table," she said.

Mortality rate lower in 2021 compared to 2020 first reported in April an apparent drop in the mortality rate of COVID-19 in 2021 compared to 2020. In the first 10,000 cases, there were 392 deaths reported, and there were 84 deaths within the second 10,000 cases.

Deaths are a lagging indicator, meaning they often occur several days or weeks after positive case trends rise. This was evidenced this past May, when 64 residents of Ottawa died due to COVID-19 following a major spike in cases in April. May 2021 was the third deadliest month for the pandemic locally, behind May 2020 and April 2020, respectively.

Overall, however, the mortality rate remains lower in 2021 compared to 2020, with 199 deaths since Jan. 1, out of 17,650 reported cases, for a raw fatality rate of 1.1 per cent, compared to 3.9 per cent in 2020.

Ninety-three per cent of Ottawa residents who died of COVID-19 were at least 60 years old. About 75 per cent of people 60 and older in Ottawa are now fully vaccinated against COVID-19.

Speaking to CTV Ottawa's Stefan Keyes on the CTV News at Six on Saturday, Etches said Ottawa is seeing the benefit of widespread vaccination.

"We really see the benefit. This protection from vaccines, along with the hard work people have been doing with masking and distancing, it has left us with almost nobody in hospital due to COVID right now," Etches said. "This is the protection we want for everyone."

Hospital ICUs in Ottawa reported being COVID-free for the first time in 2021 last week. On Tuesday, OPH reported two COVID-19 patients in local hospitals, one is 10 to 19 years old and the other is in their 80s.

A note on testing

Testing levels have been on the decline in recent weeks. Demand for testing has dropped to a point where the Heron Road assessment centre closed due to a lack of people seeking COVID-19 tests.

Testing is demand-driven in Ottawa, with people seeking out testing when they have symptoms, fear they've been exposed, or have been told to be tested due to a contact tracing investigation.

Despite lower testing numbers, the average positivity rate is also on the decline and currently sits at 0.5 per cent. At the height of the April wave, it was higher than 10 per cent.

Etches is still encouraging residents to seek out tests even if they have only mild symptoms of COVID-19.

"Testing is still very useful to find out where COVID is in our community and to better understand where it's being transmitted. It's very important as people go back to work environments where there could be transmission between co-workers," she told reporters last Wednesday.

"The message is yes; if you have symptoms that could be COVID, please go to one of the assessment centres. There's no wait for testing. You can get a same-day appointment and they can get you your result within a day."

Several cases of COVID-19 were added to Ottawa Public Health's official totals dating back to Feb. 10, 2020, prior to the first officially confirmed case being recorded on March 11, 2020. Ottawa Public Health says these previous cases are based on people who had symptoms but weren't tested until later.

"Our earliest episode date occurred in February 2020, when someone had symptoms in February but didn't get testing/testing results until March 2020," OPH said in statement.

The race against the Delta variant

Etches said Ottawa's vaccination efforts are currently outpacing the Delta variant—considered more transmissible than other strains of COVID-19—but the we haven't reached the finish line.

"We're winning, it's just that we're not at the end of the race yet," she said. "If we don't continue to have vaccination ahead of the growth of the virus, we won't succeed in the end. We need to stay ahead, so that means pushing the vaccination rate as high as we can."

There have been cases of the Delta variant in Ottawa, but Etches said there is no widespread transmission yet.

"The current situation is positive. We don't have evidence of the spread of delta in Ottawa and we see the vaccination rates growing," Etches said. "The wastewater shows that there is COVID in our community but it's not growing exponentially … and it's not leading to hospitalizations and that's what we're aiming for."

There have been 24 confirmed cases of the Delta variant in Ottawa since the strain was first identified. No one infected with the Delta variant in Ottawa has died. 


All data used in this article is from Ottawa Public Health and related data sets from Open Ottawa. Case count figures are as of OPH's daily reporting on Tuesday, July 6, 2021 and vaccination figures are as of OPH's reporting on Monday, July 5, 2021.

Infographics were built by Brenda Woods using the data above.