Throughout the pandemic, Toronto emergency physician Dr. Lisa Salamon has seen a certain type of patient show up over and over — younger adults with COVID-19 who aren't gasping for air and seem to be breathing fine.
That is, until medical teams check their oxygen levels.
"When they come in, their oxygen saturations are really low, but they have a larger reserve because they're young and healthy," said Salamon, who works with the Scarborough Health Network.
Some COVID-19 patients are even falling seriously ill so quickly that they die before getting medical attention, Ontario's chief coroner Dr. Dirk Huyer — noting that in April, at least 25 people died in their homes instead of in hospitals.
So if you get COVID-19, when should you speak to your family doctor or head to your local emergency department?
Given the range of symptoms and how quickly the illness can progress, multiple medical experts told CBC News that it's best to seek medical attention sooner than you might think.
"I think it's better earlier rather than later," said infectious disease specialist Dr. Zain Chagla, an associate professor at McMaster University in Hamilton, Ont.
WATCH | When to seek medical attention for your COVID-19 symptoms:
Worsening symptoms? Seek medical attention
Severity is, of course, a big factor in whether you need medical care, and anyone who has a truly mild case of COVID-19 can usually just rest up at home, according to Salamon.
"If someone has mild symptoms — they really feel OK, like a cold or moderate flu-like symptoms — you can ride it through," she said.
But if your symptoms start to worsen, Salamon said that's a good time to check in with your family doctor or local COVID-19 clinic.
Dr. Srinivas Murthy, a clinical associate professor at the University of British Columbia's faculty of medicine, said that given the stories emerging about previously healthy people dying unexpectedly, it's worth getting any concerning COVID-19 symptoms assessed.
And since your oxygen levels can drop without you knowing it right away, Murthy suggests that anyone with a confirmed COVID-19 infection . The small, electronic devices painlessly measure your blood oxygen level, which typically falls between 95 and 100 per cent in healthy people.
Chagla agreed it's a smart strategy to keep tabs on how you're doing, even if your breathing doesn't seem laboured.
"If you're starting to get under 95, that's getting into the range where that's not normal," he explained. "And if you're getting under 92, that's the range where you might need supplemental oxygen, which means you need a medical assessment at that point."
If you start to feel any shortness of breath, Chagla said that's also a key symptom that should prompt a trip to your local COVID-19 clinic.
"That's often, in a young person, the first sign that their oxygen levels are too low for them to compensate."
Things can go downhill quickly from there, he warned, with signs of impending critical illness including crushing chest pain, extreme shortness of breath and heart palpitations — any of which mean you should "immediately go to an emergency room."
Parents need to watch kids' symptoms, too
You can gauge your own symptoms if you're the one infected, but what if your child is the one suffering from a COVID-19 infection?
While severe cases remain rare among kids and teens, Dr. Christopher Sulowski, chief of the pediatric emergency department at McMaster Children's Hospital in Hamilton, that there are warning signs parents can watch for that are worth a trip to your local hospital.
WATCH | What to watch out for if your child has COVID-19:
Just like in adults with COVID-19, parents should monitor for any changes in their child's breathing. If it seems unusual or laboured, Sulowski said that's cause for concern. And if a child is coughing to the point where they can't catch their breath or is struggling to breathe in general, it's time to seek prompt medical attention.
It's also important to keep children hydrated when they're ill, he said, and signs of dehydration — things like excessive vomiting or fewer trips to the bathroom — would also warrant a trip to the ER.
The bottom line for anyone with a COVID-19 infection, medical experts agreed, is that COVID-19 clinics and hospitals are available to care for patients — and anyone concerned about their worsening symptoms shouldn't hold off on making the trip.
"If you're worried enough, go seek care," Murthy said.