Fatigue, fever and cough. These are the three most frequent symptoms in people infected with the Omicron variant, which has become the majority in France. For two weeks, this variant has contributed to the rise in the number of contaminations with around 300,000 new cases every day, according to figures from health authorities. Much more contagious than its Delta counterpart, it has been spotted in “74% of tests screened”, reports Public Health France (SFP) in its last epidemiological bulletin of January 6.
If the majority of cases positive for the Omicron variant are symptomatic, they are mildly, the organization notes., who studied 338 cases and tends to recognize a “lesser severity” of infection with Omicron. However, the medical community is careful not to draw hasty conclusions about the symptoms caused by Omicron, in the absence of scientific publications on the subject. Franceinfo takes stock of the elements known to date.
Fatigue, cough and fever for most patients
A trio of symptoms comes out on top with asthenia first, or abnormal fatigue, for 43% of the 338 people surveyed by Public Health France on January 4. This symptom is followed closely by cough (40%) and fever (35%). Signs that are more and more similar to those of the flu and are less severe than those caused by the Delta variant: thus, Omicron would affect more the upper respiratory tract, such as the bronchi, and less the lungs. But Public Health France specifies that the majority of patients surveyed by the organization are on average 32 years old and a small proportion of them had risk factors.
This palette is also described by some English patients as part of the Zoe Covid study which is working, via data collected in the homonymous application, to define the symptoms of patients. Work carried out under the aegis of Tim Spector, professor of genetic epidemiology at King’s College London. “For most people, a positive Omicron case will look a lot more like a cold, starting with a sore throat, runny nose and headache,” he detailed on the Zoe Covid site (article in English).
For most patients, all of these symptoms (cough, fatigue, sore throat and headache, and runny nose) seem to last between two and four days, according to a study conducted in Norway on 111 patients, and published on the site of the medical journal eurosurveillance.org, which notably publishes articles on epidemiology (article in English). The incubation period of the virus is also shorter, going from one week with the previous variants to three days on average, as specified this opinion of the Scientific Council of December 26.
Night sweats, but less loss of taste or smell
Unlike its predecessors, the Omicron variant would less often cause loss of taste and smell, one of the typical symptoms of Covid-19 until then. Only 6% of patients surveyed by Public Health France noticed anosmia or ageusia, or even both simultaneously.
On the other hand, medical teams have noted other symptoms, rather rare so far, including night sweats. At a press conference organized by the South African Ministry of Health at the end of December, doctor Unben Pillay explained that the Omicron variant could cause sweating and wake up the patient in the middle of the night. This symptom would distinguish it from other variants.
In the United Kingdom, a skin symptom has also been noticed in some children whereas it does not appear in any adult. In any case, this is the conclusion of the observations of a general practitioner interviewed on the channel. Skynews (in English) : In about 15% of children infected with the Omicron variant, it has been observed a sudden appearance of small buttons and red patches on the skin. However, to date, no published scientific study has corroborated this pediatric skin symptom.
An infection with less risk of hospitalization
According to the first observations carried out in South Africa, and according to a study from the University of Hong Kong (article in English) which is not yet peer reviewed, the Omicron strain is believed to infect more and more quickly the bronchi, leaving out the lungs. Another study, carried out on mice in Liverpool (United Kingdom), goes in the same direction and suggests that Omicron would infect the lungs less than previous variants, thus generating fewer severe forms of Covid-19, reports Release.
The British health agency (UKHSA) has also concluded, with caution, that the risk of developing a severe form with Omicron was three times lower than with the Delta variant. As for hospitalizations, they are shorter, with a 40 to 45% drop in the risk of staying in hospital one night or more. Patients generally need less oxygen.
In France, the rate of hospitalization after going to the emergency room for suspicion of Covid-19 fell from 50% to 36% in the last two weeks of December, when Omicron became the majority. Public Health France reminds however that these data should be interpreted with caution. In fact, cases of infections with the Omicron variant are still mostly observed in a young population, and therefore less at risk.
Milder symptoms for the vaccinated
Another important fact comes into account when assessing the graduation of symptoms caused by Omicron: the latter is meeting more and more people who have been vaccinated. And the more advanced the patients are in their vaccination schedule, the less the symptoms seem strong.
Thus, for people who have received their booster dose, an infection with Omicron can be like a cold. At their home, “Omicron tends to produce milder infections”, Dr William Schaffner, infectious disease expert at Vanderbilt University Medical Center in Nashville, USA, told NBC News (article in English). However, at present, studies on the subject are lacking. “What we haven’t seen yet is a substantial body of information on what the Omicron will do in unvaccinated people, ” he specifies.
While waiting to learn more, epidemiologist Antoine Flahault, also director of the Institute of Global Health at the Faculty of Medicine of the University of Geneva, ensures that vaccination remains important “to avoid severe forms” related to Omicron.