Why COVID-19 may now feel like a 'bad cold' — with headache, runny nose among most-reported symptoms
Data comes from U.K. symptom-tracking app, and experts say multiple factors could be at play
This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven't subscribed yet, you can do that by clicking here.
The most-reported symptoms of COVID-19 are now a headache, sore throat, and runny nose, according to the research team behind a U.K. symptom tracking app, and medical experts here in Canada say various factors could be causing the illness to feel more like a common cold.
The findings come from the ZOE COVID Symptom Study app, which allowed U.K. residents to report their daily symptoms throughout most of the pandemic, with scientific analysis provided by King's College London.
"Since the start of May, we've been looking at the top symptoms for the app users, and they're not the same as they were," said the team's lead researcher, Tim Spector, a professor of genetic epidemiology at King's College London, in a video statement released last week.
Headache, sore throat, runny nose and fever are now the top four reported symptoms, all while the more-infectious delta variant, also known as B1617, is sweeping mainly through people under 40 in the U.K.
"It's more like a bad cold in this younger population," Spector said.
Having a cough clocked in as the fifth most-reported symptom — less common than before, he said — while loss of smell is no longer in the top ten.
It's not clear based on the information released whether the researchers were looking specifically at symptoms reported by those who eventually tested positive for COVID-19, and the team did not respond to CBC News' requests for an interview. But other analyses by the group — including an update shared on Friday — have zeroed in on confirmed cases.
"Curiously, we did notice that people who had been vaccinated and then tested positive for COVID-19 were more likely to report sneezing as a symptom compared with those without a jab," the team wrote, noting anyone who's been vaccinated and starts sneezing frequently should consider getting tested.
WATCH | U.K. researcher says most-reported COVID-19 symptoms now milder:
In his statement, Spector stressed the shift in top-reported symptoms could be tied to the delta variant.
"All those are not the old, classic symptoms," he said.
"This variant seems to be working slightly differently."
But others say it's less likely that this highly-transmissible variant is causing an actual change in symptoms, and more likely that other factors — including the age of those getting infected, as Spector noted — may be behind the milder symptom reports.
Several Canadian experts who spoke to CBC News say vaccination programs prioritizing older adults, and a greater awareness of the range of symptoms, could both be playing a role in the shift, and it's a trend that could change how governments test and track COVID-19 infections in the months ahead.
Younger people more likely to have milder symptoms
Dr. Zain Chagla, an infectious diseases specialist with McMaster University in Hamilton, Ont., noted similar self-reported symptom data doesn't exist in Canada.
Still, he said it's likely COVID-19 is appearing more often as a cold-like illness here as well, not just the U.K., as more residents get vaccinated.
That could mean some people don't even realize they're infected, with more cases of mild COVID-19 flying under the radar.
"I would blame this more on factors in the hosts," said Chagla, "not the virus itself."
With older populations prioritized for vaccinations, younger people are more susceptible to getting infected from any coronavirus strain, and Chagla said they're more likely to have milder symptoms — unlike the acute shortness of breath and coughing typically associated with COVID-19 in more vulnerable age groups.
Canada's federal government currently lists a new or worsening cough, shortness of breath or difficulty breathing, and a temperature equal to or over 38 C — or even just feeling feverish — among the top symptoms suggesting someone may have COVID-19.
But the symptoms can "vary from person to person," officials note, with other possibilities including chills, fatigue, body aches, new loss of smell or taste, or gastrointestinal symptoms like diarrhea or vomiting.
Drawing comparisons between earlier and later rounds of symptom reporting may be tough since the age range of those still vulnerable to getting infected is changing, said infectious diseases specialist Dr. Andrew Morris, a professor at the University of Toronto.
"I think what we will find over time is that symptoms almost certainly vary according to age, and they may also vary according to strain or variants," he said.
It's also still not entirely clear why certain people have severe forms of the illness while others might not even know they're infected. Factors like older age and pre-existing health conditions, such as cardiovascular disease, can lead to worse medical outcomes, studies have long shown, though there have been rarer instances of young, healthy adults and children winding up hospitalized or even dying.
Jason Kindrachuk, a virologist and assistant professor at the University of Manitoba, noted that rising reports of mild symptoms on the U.K. app could also be tied to another factor: ever-greater awareness of the illness and the range of symptoms it causes.
"Is it truly that these are things that are related to some difference in the disease?" he questioned.
"Or is it more that we now are maybe more appreciative of those kind of minute differences, or those changes in our own health, and now maybe a little bit more prone to reporting those?"
WATCH | Deaths, hospitalizations from COVID-19 dropping among elderly:
Minor symptoms make testing more tricky
While it's good news if COVID-19 truly shows up more often like a common cold, a shift in commonly-experienced symptoms could have an impact on how regions tackle the rest of the pandemic.
Experts have warned pockets of the population with lower vaccination rates are still at risk for infections, and Chagla said milder experiences that don't warrant a trip to a testing centre or hospital could make it harder to track the virus' spread within vulnerable settings in the months ahead.
"It's going to make testing, as a strategy, a whole lot more difficult," he explained. "Especially with common symptoms being something like a headache — people get headaches for a lot of reasons."
That means community-based testing won't be a feasible option in Canada for much longer despite being a staple throughout much of the pandemic, Chagla said, since it's hard to expect people to rush out for a test at every run-of-the-mill symptom.
Instead, he said the focus should be on a targeted approach, such as testing patients for COVID-19 when they enter a hospital, or routine tests within other congregate-care settings.
Schools in particular should be a focus this fall, Chagla added, since, as it stands, only Canadian youth aged 12 and up are eligible to be vaccinated, leaving younger school-aged kids unprotected.
"We have to think about this long-term in terms of how we do surveillance, and how we monitor people, and what populations we continue to test," he said.
Kindrachuk also questioned whether people will fall back into old patterns once COVID-19 becomes less of a threat, or if the lessons of the pandemic — such as staying home when sick — will stick in the years ahead.
"I hope it's the latter… we've seen how quickly public health can change based on very self-driven or self-mediated responses, whether it's masking and staying at home or those types of activities," he said.
Various public health measures will stay in place while Canada reopens, and so far, that step-by-step process in most provinces has shown progress with rapidly-rising vaccination rates pushing down case growth, curbing the death toll, and easing pressure on the country's hospital system.
And, if the U.K. experience with shifting symptom reports proves true here as well, it could mean more people are experiencing COVID-19 as a far milder respiratory infection than the devastating illness that has taken the lives of 26 thousand Canadians over the last year-and-a-half.
"If you take the risk profile down to influenza, it fundamentally changes how we deal with this pathogen ... it's not something that shuts down society," Chagla said.
This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven't subscribed yet, you can do that by clicking here.
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