For nearly two years, the basic concern in the management of the epidemic remains to limit its effects on the hospital system. What consequences will this winter wave in which Omicron replaces Delta have on the hospital? Several elements, if they give an idea of the trend, make it difficult to provide an answer.
In recent weeks, under the effect of the Omicron variant, the cases of contamination have exploded compared to what we had known. There are now nearly 300,000 new cases every day. Vaccination has, in fact, lost effectiveness in the face of this variant. “Among symptomatic cases, Omicron is overrepresented in vaccinated people, while Delta is overrepresented in non-vaccinated people”, underlines Drees. This reflects a possible vaccine escape: Omicron further crosses the barrier created by the vaccine.
But itHow many of these cases will weigh on the hospital? Since its appearance, successive studies have pointed to a potentially lower gravity than Delta. “The first signals from the United Kingdom showed an increase in conventional hospitalizations, and not necessarily resuscitations”, notes Jonathan Roux, specialist in epidemiology and biostatistics at the School of Advanced Studies in Public Health in Rennes.? “It seems to stay more in the upper region of the respiratory system and is not going to lodge in the lungs, which could explain why it generates fewer serious forms”.
New French data published this week reinforce the idea that this proportion seems less important in the case of Omicron. A study by the AP-HP (Assistance Publique – Hôpitaux de Paris) finds a lower risk of a transition to critical care for Omicron patients than those affected by Delta.
Above all, national data published by Drees, the statistics service of the Ministry of Health, indicate that the length of hospitalization for Omicron patients appears to be shorter. It decreases by about a third compared to Delta, from 6.5 days for hospitalized patients with Omicron compared to 9.8 days with Delta. “An American study prepublished this week also confirms that patients stay in hospital for less time”
, adds Jonathan Roux, for whom the difference is explained by the fact that “the treatments are less heavy, conventional oxygen therapy makes it possible to fight against this Omicron variant”.
Note, however: the risk of hospitalization remains significant with Omicron. The observations of Drees show that vaccination protects a little less against hospitalizations than for Delta. “The WHO reminds us that Omicron should not be considered as a mild cold, because it can lead people to the hospital”, underlines the Rennes epidemiologist.
Even before Omicron, another element came to add its effects: the vaccine booster dose. With the Delta variant, an immune escape was already observed after five to six months. In other words, the effectiveness of the vaccine against severe cases decreases after a certain time.
The appearance of Omicron has accentuated this question: protection against this variant is, in fact, reinforced with the booster dose. Because if, in its presence, the vaccine acts less effectively, it continues to provide very important protection.
“According to the studies available, there is a drop in the protection offered by two doses against severe forms, in comparison with Delta”, confirms Jonathan Roux. “We see that the 3rd dose allows this rate of protection to be increased to around 90%”.
Like previous waves, but even more so with a variant that causes hundreds of thousands of new cases every day, the effect of the barrier gestures currently applied will determine the height of the incoming hospital wave. This is what the modellers at the Institut Pasteur point out in the latest update of their scenarios, with an eloquent figure: a 20% reduction in our contacts “could reduce the size of the peak in hospitalizations by 50%”.
“We risk having a high number of patients who will arrive in conventional hospitalization”, observes Jonathan Roux, while emphasizing that “we have many more conventional hospital beds in France than intensive care beds”. And on the side of these services dedicated to the most serious cases, the tension should not be as strong as that which could exist. “Modeling from the Institut Pasteur shows, in a high transmission scenario, that in critical care, there is no risk of reaching previously known levels”.
Another aspect is underlined by the scientists: the question of the duration of hospitalization. If this is reduced, “the pressure on conventional hospitalization services could be reduced”, underline the Pasteur researchers. Researchers who insist, despite everything, on the uncertainty that remains around this variant, and the major effect of the limitation of close contacts. An aspect also highlighted by Jonathan Roux: “Not everything will go through vaccination, because Omicron manages to circumvent immunity”.
letelegramme Fr Trans