Contagiousness, symptoms, vaccine… What we know about the Omicron variant

Just weeks after its discovery in southern Africa, the Omicron variant has already overwhelmed the country. Thursday, December 30, in its weekly bulletin, the health agency Public Health France indicated that more than 62% of positive cases recorded in France were due to this mutation. A meteoric arrival on the territory, while the wave of Delta is still not over. Here is what we already know about this variant.

This is its main characteristic: its contagiousness seems to be much higher than the previous strains. “Omicron is dangerous in the sense of contamination”, explained in recent days on LCI Professor Didier Sicard, former president of the National Consultative Ethics Committee. “It’s a ratio of 1 to 10: the first virus we would give it 1, the Delta we would give it 3, and Omicron we would give it 10.”

A contagiousness superior to its predecessors which is confirmed in the French figures. In recent days, the country has steadily passed the 200,000 daily positive tests mark and the incidence rate exceeds 1,250 cases per 100,000 inhabitants. Unheard of since the start of the pandemic.

But France is far from being the only country affected by Omicron. This variant was quickly detected all over the world. It has even become the majority in several territories: Denmark, where the number of cases has multiplied by 46 in three months, the United Kingdom, ahead of France, Israel, the United States or even in France by a few days. South Africa, although the wave seems to have ended.

While Omicron is more contagious than the older strains, it also causes different symptoms. According to scientists, itchy throat, skin rashes – especially in children – muscle pain or even severe fatigue regularly characterize an infection with Omicron.

Other symptoms such as cough, runny nose, fever or vomiting have also been spotted by the Centers for Disease Control and Prevention in the United States, as well as night sweats. This time, no loss of taste or smell that characterized the previous strains.

The severe forms, if they still exist, also seem to be becoming less common. In South Africa, the first country to pass the Omicron wave, hospitals have not been overwhelmed despite contamination records. “Although the Omicron variant is highly transmissible, hospitalization rates have been lower than in previous waves”, noted the South African presidency. The number of deaths was also lower than in previous peaks.

The Minister of Health Olivier Véran prefers to observe the English data, “the biggest and most reliable recoil we have”, he indicated in recent days to the National Assembly. The first figures seem to confirm the South African finding. “The figures published Tuesday evening show an increase in hospitalizations of around 49% over one week”, he affirmed in front of the deputies. “It’s an acceleration, but there is no correlation with the increase in the circulation of the virus. With the number of positive cases recorded in England, one would have expected a much larger increase (in hospitalizations). “

One of the reasons Omicron seems to be pushing fewer people to hospitals could be its lower ability to reach the lungs. According to Deenan Pillay, professor of virology in London, this variant “seems to infect upper respiratory tract, throat cells”, rather than “the cells of the lungs”, he tells the Guardian. One way for the virus to be more transmissible, but less virulent. Conversely, “a virus which infects lung tissue well is more dangerous, but less transmissible”, explains the virologist.

To avoid saturating its healthcare services, France is banking on vaccination, and in particular the recall campaign. While this remains effective in preventing severe forms, it prevents contamination less than with Delta. “In the current context, if you are vaccinated with three doses, but positive for Covid-19, the infection will more likely come from the Omicron variant than from the Delta”, explained last week to LCI Philippe Amouyel, professor of public health at the Lille University Hospital. “Vaccination protects, although this variant is somewhat more resistant to the vaccine than its predecessor.”

According to data from Imperial College London, two months after the booster dose, protection against hospitalization caused by Omicron remains between 80% and 86%.