Since the discovery of the first cases of the Omicron variant, governments around the world have been closing their borders in fear.  Omicron has been classified as "worrying" by the WHO and Omicron is still very much a mystery to the scientific world.
 On the genetic side, this variant has an unusually high number of mutations, including about 30 in the Spike protein, the key to entry of the virus into the body. Based on experience with previous variants, it is known that some of these mutations may be associated with increased transmissibility and decreased vaccine effectiveness.

"If we base ourselves on genetics, indeed, it is something very particular which can be worrying", affirmed on November 26 to the AFP Vincent Enough, of the National Center of Reference of the respiratory viruses of the Pasteur Institute in Paris.

The South African scientists released this Friday, based on the analysis of 35,670 re-infections identified in nearly 2.8 million individuals who tested positive, the risk of catching Covid-19 again is increased with the Omicron variant. According to their research, it is three times more contagious than the Beta and Delta variants.

Between November 1 and 27, the risk of reinfection observed was three times higher compared to waves linked to the Beta and Delta variants. "The Omicron variant is associated with a substantial ability to escape immunity from prior infection," concludes the study, which was made available Thursday on the medRxiv pre-publication site but has not yet been peer-reviewed.

"We believe that previous infection does not protect against Omicron," Anne von Gottberg, an infectious disease specialist at South Africa's National Institute of Communicable Diseases (NICD), had earlier said. However, according to initial observations, people re-infected with the variant often had less severe symptoms, she said.  
 "We have no information on the vaccination status of individuals in our data, so we can't draw any conclusions about Omicron's ability to escape vaccine-induced immunity," warned Juliet Pulliam, from South Africa's Stellenbosch University, and lead author of the study, on Twitter. The majority of experts remain largely cautious on the subject for the moment.

"It is urgent to adopt the RNA vaccines and boosters to the variants in circulation," said the French virologist Etienne Decroly on Twitter. If it is necessary to change the existing vaccines, we may be able to get them approved within three to four months," as soon as manufacturers "start to modify" their serums, said Emer Cooke, the head of the European Medicines Agency on November 30.

Pfizer and Johnson & Johnson (J&J) said Monday that they and Moderna had begun work on a new version of their covid vaccine specifically targeting Omicron in case current vaccines are not effective enough against the new variant.
 According to the WHO, the variant is now present in at least 22 countries, including four African countries: Ghana, Nigeria, Botswana and South Africa.  The number of official cases of Covid-19 has increased by 54% on the continent over the last seven days compared to the previous days, due to the exponential increase in infections in South Africa, where it is already dominant. Two weeks ago, that country was reporting about 300 cases a day. On Wednesday, it reported 8,561 new cases, compared to 4,373 the day before.

In France, nine cases of contamination have been reported so far. After Reunion Island, the first three cases detected in mainland France were announced on Thursday, in the Ile-de-France, in the Haut-Rhin and in the Vendée, each time in travellers returning from Africa. In Europe, cases have been detected in other European countries such as Spain, Switzerland, the Netherlands, Norway, Germany, Belgium and the United Kingdom.

In the United States, five cases of the Omicron variant were confirmed on Thursday in New York State, one in California, one in Minnesota and one in Hawaii, bringing the total of confirmed cases in the country to 10.

Australia announced on Friday the first three cases of Omicron in Sydney, despite a ban on foreigners entering the country and flight restrictions to southern Africa.