According to the ZOE COVID study, which monitors self-reported symptoms in participants using a smartphone app, those infected with Omicron are less likely to be hospitalized and lose their sense of smell than people with Delta.
The study also found that some of the “most debilitating symptoms” of COVID-19, such as brain fog, burning eyes, dizziness, fever and headaches, were also less common in Omicron cases.  Participants infected with Omicron were also less likely to report coughing, according to the study.
“The prevalence of symptoms characterizing an omicron infection differs from that of the Delta SARS-CoV-2 variant, apparently with less involvement of the lower respiratory tract and a reduced chance of hospitalization,” the study authors wrote.
However, the researchers report two symptoms that were “consistently prevalent” in both variants, regardless of the vaccination status of each – sore throat and hoarse voice.
The findings were published Thursday in the medical journal The Lancet with reviewers and will be presented at the European Conference on Clinical Microbiology and Infectious Diseases later this month.
Researchers from King’s College London studied the symptoms of 63,002 vaccinated participants in the United Kingdom who tested positive for COVID-19 between 1 June 2021 and 27 November 2021, when the Delta variant was the dominant strain, and on 22 December 2021 until on January 17, 2022, when Omicron became dominant.
Patients from each group were matched and compared with one person of the same age, sex, and vaccination dose in the other group.
The study did not compare symptoms, hospital admissions or duration of infection from the two variants in unvaccinated individuals.
According to the findings, the biggest difference in symptoms between the two variants is the loss of smell, which occurred in 52.7 percent of Delta cases compared to less than 20 percent of Omicron cases.
The researchers found that the symptoms lasted an average of 6.9 days when infected with Omicron, compared with 8.9 days for those infected with the Delta variant.
The shorter duration of Omicron symptoms was also more pronounced in people with three doses of the vaccine, underscoring the importance of booster shots, the researchers said.
“Shorter onset of symptoms suggests – pending confirmation from viral load studies – that the period of infection may be shorter, which in turn will affect workplace health policies and public health guidelines,” the authors wrote. of studying.
In addition, the study found that hospital admissions were 25 percent lower during the Omicron-dominated period.
The study supports previous findings showing that the Omicron variant is milder in vaccinated populations in terms of severity, although it is more contagious than the Delta variant.
According to the Public Health Service of Canada, common symptoms of COVID-19 include runny nose, headache, new or worsening cough, shortness of breath, fever, sneezing, fatigue, body aches, and loss of smell or taste.
However, the agency notes that these symptoms may vary from person to person in different age groups, as well as depending on the variant with which they are infected.


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