“The fifth wave has been here since mid-October”, said the President of the Scientific Council, Jean-François Delfraissy, Wednesday November 17 on France Inter. After the decline that began at the end of the summer, contaminations and hospitalizations have started to rise again, while the death curve is shaking.
This epidemic resumption displays an air of déjà vu: in the fall of 2020, the country was facing its second wave of Covid-19. While seasonality seems to play an important role, other factors, such as vaccination, clearly differentiate the two fall episodes. In support of infographics, franceinfo analyzes the main differences between these two waves and provides an overview of the current epidemic rebound.
How fast is the epidemic progressing, compared to the wave of autumn 2020?
The incidence rate, that is to say the number of contaminations per 100,000 inhabitants in a week, exceeded the threshold of 100 on Tuesday. In 2020, this symbolic rate was exceeded on September 14, but the contaminations had really exploded in October, leading to confinement from October 30. This year, the incidence rate has not exploded, but its sustained increase is enough to worry the authorities.
Renaud Piarroux, epidemiologist and head of department at the Pitié-Salpêtrière hospital in Paris, identifies three main causes for this recovery. “There are seasonal factors, linked in particular to the drop in temperatures; the relaxation of barrier measures, which people are fed up with; and a decrease in protection by vaccination.”
What changes from the fall wave of 2020 are vaccines, which reduce the risk of developing severe forms. We can observe this by comparing the new hospitalizations of patients with Covid-19 between the two periods. The two waves appear similar in terms of incidence, but the progression of hospitalizations in 2021 is slower. An observation to be refined in the coming days, in view of the recent worsening of the figures: the curve is close to the threshold of 500 new hospitalizations per day, on November 16. This, while hospitals are already affected by other seasonal pathologies, including an epidemic of bronchiolitis.
As for deaths in hospital linked to Covid-19, they barely shudder. Given the time lag between contamination, hospitalization and potential death, it seems too early to compare the current wave with that of autumn 2020 on this indicator.
Does the delisting of tests disrupt the monitoring of this new wave?
Notable difference concerning this rebound in autumn 2021: the testing policy is no longer the same. Since October 15, Covid-19 screening tests are no longer reimbursed in a number of situations. If you are not vaccinated, do not have a medical prescription, or are not in contact, you must pay between 22 and 44 euros, depending on the test performed. By reducing the possibility of doing “comfort tests”, the government wanted to reduce the bill and encourage the last French to be vaccinated.
As a result, the number of tests dropped. From around 440,000 samples taken every day around October 10, we went down to around 300,000 per day at the end of October.
The thermometer has therefore changed, confusing the monitoring of the epidemic a little. This is what the Scientific Council feared in an opinion delivered on October 5 : “A certain form of difficulty in interpreting epidemiological data could be increased from mid-October by the reduction in the number of tests carried out due to their delisting”.
As the tests remain free in many cases, the reduction in the number of samples has mainly concerned unvaccinated and non-symptomatic people, and has remained constant for others, who are more likely to receive a positive result. This does not prevent a slight underestimation of the incidence rate, since part of the comfort tests could still make it possible to detect positive people. “We don’t know exactly what we are missing”, concedes Renaud Piarroux.
In addition, the objective of encouraging vaccination by making paying for “comfort tests” does not seem really achieved, if we are to believe the curve for first-time injections, which has not seen a rebound since the start. second half of October. While 10% of French people over 18 have not yet received any dose, barely more than 17,000 first doses per day are injected, against more than 350,000 at the height of the campaign, in early August.
Why is vaccination becoming all the more strategic?
People who have not yet received any dose are more likely, in proportion to their total workforce, to pass through the doors of hospitals due to Covid-19, than people who have been fully vaccinated. The following graph shows how the unvaccinated people were already more affected during the fourth wave. As of October 31 (the date for which the latest figures are available), there were 11.74 new hospitalizations per million unvaccinated people, against 1.69 per million vaccinated people.
It is also a race against time that has started regarding the booster injections. Recent studies have confirmed the decline in protection from vaccination after several months. “Even if the immunity is good at one point, it can erode”, summarizes Renaud Piarroux. The health ministry insisted on Tuesday: “The absolute priority is the primary vaccination of the oldest people who have not yet been vaccinated, but also the acceleration of the recall campaign.” Time is running out: older people or people with co-morbidities are both the most vulnerable, and those who received their first doses longer ago.
More than 4.6 million booster doses have been injected so far, and the ministry said it was confident about the number of reservations made for the coming weeks, and the vaccine stocks. It plans new communication campaigns to speed up recalls, open to people over 65 and people with co-morbidities.
“We are not making enough effort to administer the booster doses, believes Renaud Piarroux, however. It’s seen as ‘do it if you want’, but we’re going to have to think about a third dose for everyone. “ Injections of “booster” doses for those over 50 should begin in early December. “The challenge is to see what situation we will find ourselves in before the Christmas holidays. If we control the transmission, it will be easier. If things go wrong like in Germany, it will fall on us at the worst possible time. . “