Don’t ignore that sneeze or scratch the back of your throat. What
coronavirus
variants continue to evolve and become harder to detect, as do the symptoms of COVID, allowing more people to unwittingly spread the virus.
Signs of infection are getting harder to tell apart from symptoms of a common cold or the flu, according to the latest update from the
Zoe Health Studya joint project of
researchers
at Harvard, Stanford and King’s College London.
A mild runny nose, headache, or sore throat could now precede a positive test result with one of omicron’s many ramifications.
Other indicators commonly reported during earlier phases of the pandemic, such as loss of taste and smell, have dropped down the list.
In addition to finding generally milder symptoms caused by omicron than previous variants, the study showed that symptoms also varied by vaccination status.
For example, nasal congestion is the third most frequently cited symptom in people who completed their initial two-dose vaccination series, while those who only received one injection reported sneezing, and for the unvaccinated, it is fever.
“What changed is people’s general immunity,” said Peter Chin-Hong, an infectious disease expert at UCSF who was not involved in the study. “On a continuous scale, as their bodies experience more with COVID, the symptoms are milder overall.”
In other words, the virus threat remains unchanged. But thanks to widespread immunity derived from vaccinations and previous infection, most people are now better equipped to fight off the more serious manifestations of the disease.
“Through painful steps, many deaths, and millions of infections, as a population, our immune systems have become stronger and more intelligent,” said Jorge Salinas, an epidemiologist at Stanford, who was also not involved in the study. “Humans are not the same as in 2020. Now we can recognize the virus and modulate the response to infection.”
Splitting the data into three categories (fully vaccinated, partially vaccinated, and unvaccinated), Zoe Health researchers found that the four most common symptoms of COVID-19 among all groups now are sore throat, runny nose, persistent cough, and headache.
“Overall, we saw similar symptoms of COVID-19 reported overall on the app by people who had and had not been vaccinated,” the researchers wrote. “However, those who had already received an injection reported fewer symptoms over a shorter period of time, suggesting they were getting less severely ill and getting better more quickly.”
So how did the lists differ? Here are the main symptoms for each group, according to daily data collected by the UK app Zoe.
fully vaccinated
1. Sore throat
2. Runny nose
3. Stuffy nose
4. Persistent cough
5. Headache
A dose of vaccine
1. Headache
2. Runny nose
3. Sore throat
4. Sneezing
5. Persistent cough
not vaccinated
1. Headache
2. Sore throat
3. Runny nose
4. Fever
5. Persistent cough
Despite the evolutionary nature of the virus, the
Centers for Disease Control and Prevention website
it still highlights loss of smell, shortness of breath, and fever on its list of telltale signs of infection, even though they ranked 6th, 29th, and 8th, respectively, on the Zoe list of vaccinated people.
“A persistent cough now ranks at number 5 if you have received two doses of vaccines, so it is no longer the main indicator of having COVID,” the researchers said.
A
one year study
earlier this year, of more than 60,000 people tested for the coronavirus in San Francisco, they found similar changes in
Symptoms of COVID-19
over time, including fewer reports of loss of smell, once considered a trademark of the disease.
More people reported upper respiratory infection symptoms during the omicron surge than in previous waves, according to researchers at UCSF and the Chan Zuckerberg Biohub in coordination with
the San Francisco Latino Task Force. Patients also experienced fewer cases of systemic problems like fever and body aches.
“Our report and others showed that a transition occurred with clinical symptoms more common with omicron to a higher proportion of people with congestion, more common with sore throat, and less common with loss of smell or taste compared with delta and the variant earlier,” he said. Dr. Diane Havlir, an infectious disease expert at UCSF and lead author of the San Francisco study.
Salinas said these changes are to be expected: “It is beginning to behave like other respiratory viruses.”
But as the symptoms of COVID-19 become milder and easier to ignore, the urgency to get tested becomes greater. Public health officials anticipate another spike in cases this winter with people spending more time indoors and traveling for the holidays.
Early detection of positive cases is vital to slow the spread of the virus and prevent further immunoevasive strains of the virus from emerging.
There is no guarantee that future variants will continue to cause milder disease, even among those vaccinated.
Chin-Hong said the tests are also a good protection for high-risk people, especially if they face possible delays in acquiring treatments like the antiviral drug Paxlovid, which is in demand.
“A lot of people are not being diagnosed now because they don’t think it’s a big deal,” he said. “But getting a diagnosis will open the door for therapy.”
An earlier version of this story misrepresented the most common symptoms for unvaccinated people and those with one dose.
Aidin Vaziri (he/he) is a writer for the San Francisco Chronicle. Email: avaziri@sfchronicle.com