A study by the Institut Pasteur explains that vaccination must be accompanied by additional health measures to slow the progress of coronavirus
The progress of the vaccination campaign against coronavirus Covid-19 in France will not, without additional restrictions, prevent a jump in hospitalisations to a level above the peak of the first wave, estimates a study by the Institut Pasteur published on Wednesday. This rebound in hospitalizations, down slightly since early February, is linked to the progression of the mutation of British origin of the coronavirus, estimated 50% more contagious than the historic strain. It should represent the majority (56%) of new cases from March 1st and almost all (91%) a month later, according to the researchers’ models.
On the assumption that 100,000 doses of vaccines per day would be distributed until April, then 200,000 thereafter, “we expect to have 28% less hospitalizations on April 1, and 46% on May 1”, compared to a scenario where there would be no vaccine available, explained Simon Cauchemez, responsible for mathematical modelling of infectious diseases at the institute. “We see that vaccination” has a real “impact on the health system”, he observes. But even if it “succeeds very strongly in mitigating the impact of variants”, the situation will remain “complicated without further reduction in transmission rates”.
Crush the dynamics of the epidemic to delay the recovery
While the timing of this new peak is difficult to predict, “in most scenarios we expect there to be a recovery”. The number of new hospitalizations could approach 4,500 per day, against about 3,750 at the peak of the first wave, and a little more than 2,500 for the second. French hospitals have recorded 9,362 hospitalisations over the last seven days, according to Sante Publique France, an average of 1,337 per day. To avoid this situation, “we have approaches that work well against the historic virus, but which risk being insufficient against the British mutation,” said Simon Cauchemez, referring in particular to the curfew.
While the government announced localised confinement over the weekend in the Alpes-Maritimes and Dunkirk, the team of researchers is not commenting on the effectiveness of this or that measure. But she notes that “achieving significant reductions in the transmission rate would make it possible to crush the dynamics of the epidemic and have a restart later, at a time when more people will be vaccinated”, underlines Simon Cauchemez.
In another study, the Pasteur Institute also estimates that around 17% of the adult population has now been infected with the Sars-CoV-2 virus and therefore “could have acquired immunity (at least partial and short-term) “. This rate varies greatly depending on the region, from around 5% in Brittany to 30% in Ile-de-France. Close to 25% in 20-39 year olds, it then decreases with age, to around 11% in those over 70. At the end of the first confinement, in May, the research organization estimated “that this proportion should be around 5% at the national level.