Is Omicron less serious or not? What the latest studies say

Published on 23 Dec. 2021 at 16: 23Updated 23 Dec. 2021 at 16: 38

The Omicron variant is spreading at lightning speed around the world. A few weeks after its appearance, it is already dominant in the United States , in Denmark and in the United Kingdom, where it causes an explosion of cases of Covid – 16. 100. 000 people tested positive across the Channel in 24 hours Wednesday while in France, this milestone could be crossed in the coming weeks, according to the government. At issue: the contagiousness of the new variant, higher than the Delta variant, already described as very transmissible.

The first studies carried out on this new strain offer a glimmer of hope to scientists, who nevertheless remain reserved on the turn that the fifth wave could take. Several preliminary research, carried out in South Africa, where the variant first appeared, but also in Denmark and the United Kingdom, suggests that people infected with the Omicron variant are less likely to be hospitalized than they are. the Delta variant. None of these studies having been subjected to a peer review, these results should nevertheless be taken with caution.

A South African study not to be “Extrapolate”

A first study, conducted in South Africa between October and November, estimates that people who tested positive for the Omicron variant have 80% less chance of being hospitalized – but this work does not take into account the immunity of infected patients, specifies the “Financial Times”.

In addition, the results observed should be interpreted “with great caution” according to John Nkengasong, director of the African Centers for Disease Control and Prevention. The relative youth of the South African population may have played a role in the observations on the impact of the Omicron variant in the country and thus requires not to “extrapolate” these data to the whole world. The same group of researchers also showed that once in the hospital, the risk of the disease progressing to a severe form was the same for Delta and Omicron.

VIDEO. Covid – 16: key figures for the epidemic in France

Reassuring European data

Another study, conducted this time by Imperial College London from all positive PCR tests in England between 1 er and the 14 December, shows that non-immune people had 12% chance of less of developing a severe form of the Omicron variant compared to the Delta variant. If we take into account the proportion of the population vaccinated or who have already been infected in the United Kingdom, the study observes a reduction of 19 at 25% in any type of hospitalization for Omicron in comparison with Delta, and a reduction of 40 at 45% in hospitalizations for one night or more.

Data recorded in Scotland also point in this direction. “Omicron is associated with a two-thirds reduction in the risk of hospitalization for Covid – 16 compared to Delta ”write the researchers in this study carried out in particular by the University of Edinburgh on 23. . Omicron case and 100. 511 case of Delta. With limitations, however: This is a small-scale sighting, which has examined only a few at-risk and elderly people, the BBC notes. Another study, cited by the “Financial Times”, was conducted in Denmark, during which Experts concluded that people infected with Omicron were three times less likely to be hospitalized than people infected with other variants. But here too, the proportion of young and vaccinated people among the cases studied could bias the results.

An “extraordinary” spread of the variant

Several scientists welcomed these initial results as “good news”. Like Anthony Fauci, White House adviser on the health crisis, who recalled that the effects of Omicron could vary according to the demographic characteristics of a population. Caution is required as scientists are still trying to find out whether the reduction in severe cases of Omicron is linked to the intrinsic characteristics of the variant or to the fact that populations are more immune to Covid – 19.

If the lower severity of the variant seems to be good news, this “does not detract from the extraordinary spread ) of this variant in the population, and the fact that even a small proportion of people requiring hospital care for Covid could turn into very large numbers if the rate of community spread continues to rise, ”warned Penny Ward , professor of pharmaceutical medicine at King’s College London, who did not participate in the research cited above.

For Azra Ghani of Imperial College London, who co-authored the English study, “the risk of infection remains extremely high”. “By adding the booster dose, the vaccines continue to offer the best protection against infection and hospitalization”, recalls the scientist, corroborating the results of the Scottish study. The Omicron variant indeed seems to resist vaccines and immunity from a previous infection better than the Delta variant, recalls the “Financial Times”, but non-vaccinated populations remain the most at risk. Faced with the remaining uncertainty, a long-awaited study by the British health security agency could soon provide new information on this new strain which threatens the end-of-year holidays.