Key Points

In Week 43, the incidence rate of new COVID-19 cases remained generally stable in Île-de-France compared to the previous week. Given the shift in testing patterns following the removal of reimbursement for tests and the school holidays, the indicator should be interpreted with caution, as a slight underestimation cannot be ruled out. The increase in the positivity rate among symptomatic individuals confirmed the resurgence of SARS-CoV-2 circulation observed in the region since Week 41. Against a backdrop of increased social contact, reduced adherence to preventive measures, incomplete vaccination coverage—particularly among children—potential waning of immunity over time, and falling temperatures, all indicators must be closely monitored in the coming weeks.

In Week 43, the crude incidence rate among residents of the Île-de-France region remained stable for the second consecutive week at 73 cases per 100,000 inhabitants (vs. 71 per 100,000 in Week 42). The stability of the incidence rate in the region masked disparities across departments and age groups. The testing rate continued the downward trend that began in Week 33. In Week 43, the decrease in testing was primarily due to lower testing rates among children under 15, owing to school holidays. The positivity rate increased among those under 15 and, to a more moderate extent, among those aged 30–44 and 65–74. The rise in positivity continued among symptomatic individuals. The Delta variant has remained the dominant strain in Île-de-France since Week 25.

At the hospital level, new hospitalizations, critical care admissions, and in-hospital deaths show an apparent weekly decrease. This reduction should be interpreted with caution, particularly due to a possible delay in data entry into the SI-VIC system, as the entry delay is likely to increase significantly during the holiday period, compounded by a public holiday on November 1. At the regional level, the number of deaths from all causes and across all age groups in Île-de-France remained within the usual fluctuation range.

In week 43, 75.7% of the Île-de-France population had received at least one dose of the vaccine, and 73.2% were fully vaccinated. The rate of increase in vaccination coverage, however, remained low (VAC-SI data as of November 2, 2021, not shown).

Against the backdrop of schools and workplaces reopening and persistently high viral circulation, vaccinating all eligible individuals remains essential and must be combined with high adherence to other preventive measures, particularly adherence to barrier measures, limiting high-risk contacts, and self-isolation in the event of symptoms, a confirmed infection, or contact with a confirmed case. It is the combination of various individual and collective measures that helps limit the transmission of SARS-CoV-2 and can be decisive in reducing viral circulation and preventing severe cases and further strain on hospitals.