- Sore throats and runny noses are increasingly common in people vaccinated with Omicron.
- But Omicron patients report fewer cases of fever, cough, and loss of taste or smell.
- The tables below show which symptoms of Omicron are most common and how they compare to previous variants.
Almost as soon as Omicron started spreading, doctors noticed slight differences in their patients’ symptoms compared to previous variants. Mild cold-like symptoms such as sore throat, sneezing and runny nose were increasingly common – but old hallmarks of COVID-19 like fever, cough and loss of taste or smell had diminished.
“The most reported symptoms of Omicron are definitely cold-like, especially in vaccinated people,” Dr. Claire Steves, scientist involved in the Zoe COVID Symptom Study, said in a recent video.
The Zoe study uses a smartphone app to record how hundreds of thousands of people feel every day across the UK. It offers a comprehensive overview of the evolution of COVID-19 symptoms during the pandemic, especially with the advent of the Delta and Omicron variants.
The following chart shows how Omicron’s symptoms compare to those of its predecessors, based on data collected by the Zoe app.
Runny nose, headache, fatigue, sneezing and sore throat were the top five symptoms among people in the UK who have tested positive for COVID-19 in recent weeks. Meanwhile, only 44% of people in this group reported a persistent cough and 29% reported a fever. Loss of taste or smell was even less common, as shown in the table below.
Although the data does not distinguish between vaccinated and unvaccinated people, 70% of the UK population received at least two doses of the vaccine on Thursday.
Omicron cases often begin with an irritated sore throat, headache, and congestion
Dr. Jorge Moreno said he recently saw an influx of COVID-19 cases at his outpatient clinic in Connecticut. Most of these patients are vaccinated, he said, so their symptoms tend to be milder and relatively short-lived.
Many patients begin with a dry, scratchy throat that causes sharp pain when swallowing.
“It’s a very important symptom,” Moreno, an assistant professor of medicine at Yale School of Medicine, told Insider. “It’s not like a little tickle in the throat. If they report it, they say their throat is raw.”
Sore throats are often associated with sinus congestion and headaches, he added, followed by a cough a day or two later. At a press conference in December, Ryan Noach, CEO of Discovery Health, South Africa’s largest private insurer, said Omicron patients typically report a sore throat first, followed by a nasal congestion, a dry cough and body aches.
“Cough is always part of the symptoms, [but] it’s not as bad as before,” Moreno said. Vaccinated people, he added, “don’t have these respiratory symptoms as much.”
Loss of smell is also relatively rare in Omicron patients.
As of this month, less than 20% of people in the UK who have recorded a positive COVID-19 test were recording the symptom in the Zoe app. In June, when the Delta variant was dominant in the UK, loss of smell was the sixth most common COVID-19 symptom among fully vaccinated people. In March, before Delta was detected and vaccines were widely available, 60% of UK adults aged 16-65 on the Zoe app reported a loss of sense of smell at some point in their illness.
By contrast, fatigue is increasingly pronounced among outpatients, who often report feeling tired and achy, Moreno said.
“I’ve seen a lot more people report fatigue as one of their main symptoms,” he said. “These are youngsters who can usually get through things. They need rest. They need sleep. They nap more.”
Why are the symptoms of COVID-19 changing?
Scientists don’t know exactly why COVID-19 symptoms change.
Vaccines help reduce the severity of the disease, but Omicron could be a less virulent virus on its own. Two recent lab studies, which have not been peer-reviewed, suggest that Omicron may be less effective at attacking lung cells than previous variants. Another not yet peer-reviewed study, published Wednesday, found that Omicron inherently reduced the risk of serious hospitalization or death from COVID-19 by 25% compared to Delta.
Omicron can also change the way the virus replicates or collects in the body. A December study from the University of Hong Kong, which has not been peer-reviewed, found that Omicron replicates 70 times faster in the main airways, or bronchi, compared to Delta, but 10 times slower in lung tissue. Another pre-print study, published earlier this month, showed that the viral load from an Omicron infection peaked in saliva one to two days before peaking in nasal swabs – a sign that Omicron can infect the throat before it infects the nose.
Still, doctors have noticed a clear gradient of symptoms depending on a person’s vaccination status.
“Unvaccinated people follow a slightly longer and more difficult journey,” Moreno said. “Vaccinated people have a middle course. Boosted people, in many cases, it’s almost like an old cold: sinus symptoms, sore throat.”
Before Omicron, Moreno said, his COVID-19 patients felt crummy for about 10 to 14 days. Lately, he said, people who received a booster shot report shorter bouts of illness than those who received fewer or no doses.
“These individuals who are boosted, within five days, seven days of the onset of their symptoms, their energy levels return,” he said. “Their symptoms are resolved.”