Don’t be fooled by fewer COVID-19 hospitalizations: epidemiologists
Ontario’s COVID-19 case numbers are the highest they’ve ever been, yet our hospitalization rates are lower than they were at the height of the first wave of the pandemic last spring.
At the peak of the first wave on April 25, there were 5,675 active cases and 925 people in hospital. Later, on May 5, the number of people in hospital peaked at 1,043, with 223 people in intensive care. As of Oct. 22, Ontario reported 6,930 active cases but only 270 hospitalized patients, and 74 in the ICU.
At a glance, might create the impression that the severity of infections this time is lower, that people are recovering more easily and that hospitals are not at as high a risk of becoming overburdened with COVID-19 patients.
But, say two public health and infectious disease experts, that would be a dangerous assumption to make. Not only are hospitalization numbers not capturing the full severity of the wave we’re currently in, but they tend to lag significantly.
Kednapa Thavorn is a senior scientist in the Ottawa Hospital Research Institute’s clinical epidemiology program, and an assistant professor in the University of Ottawa’s school of epidemiology and public health.
She warned that the proportion of critically ill COVID-19 patients might appear lower as a share of the total caseload this time because the province’s increased capacity for testing means a broader sample of the population is being tested. So patients who are most vulnerable and most likely to require hospitalization are being eclipsed by the larger number of younger, less vulnerable people whose diagnoses were recorded by broader testing.
These charts updated daily by the provincial government plot the number of active COVID-19 cases, hospitalizations and ICU admissions in Ontario from April 2 to Oct. 22, 2020. The numbers are not cumulative. — Government of Ontario graphic
“During the first time around, the prevalence or incidence of older people testing positive may have looked higher because we had fewer resources and we were targeting them specifically,” she said.
“Lately, because we have larger capacity and better access to testing, the people who have had access to this test are actually a wider part of the community.”
A lower share of people with serious infections compared to those with mild infections isn’t something Ontarians should let their guard down over, she said, since we know it’s common for hospitalization rates to lag behind infection rates in daily tracking. This is partly due to the fact that people typically aren’t admitted to hospitals at the onset of infection, but several days later. So while the number of people in hospital might be lower now than during the peak of Ontario’s first wave, it won’t necessarily stay that way, especially if people don’t follow public health guidelines.
“I want to put a caution on the message that we should have peace of mind because younger people are healthier,” she said. “I still emphasize the need for public health measures, social distancing and putting on a mask. Regardless of who gets infected with COVID-19 they still have a chance to infect other people.”
Dr. Curtis Cooper is a scientist in the Ottawa Hospital Research Institute’s clinical epidemiology program and a medical doctor working at the Ottawa Hospital’s general campus.
Based on his firsthand experience during the first wave of the pandemic, Cooper, like Thavorn, expects hospitalization rates to get worse before they get better.
“We’re still really early in the second wave and I’m unfortunately very confident our numbers in the hospital and the ICU are going to start to increase. I think we’re starting to see that already,” he said. “So just like in the first wave you saw a bit of a lag in case diagnosis and people in ICU, I think we’re seeing the same thing here.”
Cooper also said case, hospitalization and ICU numbers don’t necessarily capture the full COVID-19 caseload in seniors and people with comorbidity — the presence of more than one illness or condition simultaneously — if deaths are attributed to another cause, despite the actual cause being COVID-19. This can skew the numbers, too.
“They get sick and die and never end up going to the hospital and those numbers aren’t included,” he said. “For personal reasons and family reasons and other reasons, people sometimes just don’t go. They say ‘I’m going to die at home, or in my long-term-care facility.’”
Cooper said Ontarians should trust health-care professionals when they say the province’s COVID-19 situation is dire, and take action to avoid making it worse. In addition to following the usual public health guidelines around COVID-19, he said Ontarians should make getting this year’s flu vaccine a priority. Doing so can help save health-care resources for the care of patients with COVID-19, and protect elderly and immunocompromised people from dangerous flu infections.
“We have a vaccine for influenza and people really do need to go out and get it. It’s going to help protect them and it’s going to help protect the vulnerable in our community,” he said. “When we’re thinking about ‘What I can do as a citizen?’ and what governments can do, the focus needs to be on protecting our most vulnerable.”
These charts updated daily by the provincial government plot the number of active COVID-19 cases, hospitalizations and ICU admissions in Ontario from April 2 to Oct. 22, 2020. The numbers are not cumulative. — Government of Ontario graphic