COVID-19 Public Health Bulletin for the Île-de-France Region, November 2021

Published on 16 November 2021

Key Points

A consistent gradual increase in SARS-CoV-2 infection incidence and positivity rates was observed from Week 32/2020 through the peak of the second wave in Week 44/2020. Coinciding with the second national lockdown, viral circulation declined, then plateaued at a high level, before resuming an exponential phase starting in Week 06/2021 and reaching the peak of the third wave in Week 13/2021. This third wave corresponds to the spread of the Alpha variant. A significant increase in testing capacity is observed, with peak activity in S13/2021.
The detection rate for symptomatic cases is generally lower across all analysis periods than that estimated for asymptomatic cases. Conversely, the positivity rate is generally higher among symptomatic individuals.
Starting in Week 32/2020, the incidence rate is generally higher for asymptomatic cases under 15 years of age and 75 years and older. It is higher among symptomatic cases for those aged 15–64. For those aged 65–74, this rate is similar for symptomatic and asymptomatic cases.
At the peaks of the second and third waves, the eight departments in the Île-de-France region had incidence rates exceeding 400 cases per 100,000 inhabitants.
Unlike most regions in metropolitan France, the epidemic activity observed in Île-de-France during the third period was more intense than that observed during the second analysis period, regardless of the department or age group in question.

Île-de-France had the highest hospitalization and critical care admission rates in metropolitan France during periods 1 and 3, with the third period showing the highest rates: 456.2 per 100,000 inhabitants (hospitalization rate) and 109.6 per 100,000 inhabitants (rate of admission to critical care).
In total, between March 2020 and May 2021, 117,314 new hospitalizations (mostly among those over 80) and 24,696 new critical care admissions (mainly among those aged 60–79) were recorded.

Since March 2020, 1,054 patients (median age 63 years) confirmed positive for SARS-CoV-2 have been documented following admission to sentinel intensive care units in the Île-de-France region.
A moderate increase in the proportion of women admitted to intensive care was observed during the three periods.
94% to 98% of deceased cases had either a comorbidity or were aged 65 years or older.

4,917 COVID-19 episodes were reported in ESMS; 31% during the first period, 41% and 28% during the second and third periods, respectively.
The occurrence of confirmed COVID-19 cases was more pronounced during the first period. In total, there were 33,619 confirmed cases (51% of which occurred in the first period) among residents and 16,464 (47% of which occurred in the first period) among staff members. The majority of cases occurred in nursing homes.
Of the 7,658 deaths among residents, 77% occurred during the first period. 70% of these deaths occurred within the facility.
The incidence rate, hospitalization rate, and case fatality rate among residents were higher during the first period. The decline in the third period is linked to vaccination and high vaccination coverage in long-term care facilities.

The number of emergency department visits for suspected COVID-19 was higher during the first wave of the epidemic, while the second and third waves were more spread out over time.
The proportion of COVID-19-related activity among all emergency department visits was higher during the first wave, peaking at 32.7% in S13/2020.
The proportion of COVID-19-related hospitalizations among all hospitalizations following emergency department visits was higher during the first wave, peaking at 43.9% in week 13 of 2020.
The number of SOS Médecins calls was higher during the first and second waves (2,907 calls and 1,582 calls in S13/2020 and S43/2020, respectively) and more moderate but spread out during the third wave (853 calls in S12/2021).
The share of COVID-19-related activity among all SOS Médecins calls follows the same downward trends, with respective peaks of 29.8%, 14.8%, and 7.5%.
The activity levels of emergency departments and SOS Médecins are generally consistent.
The hospitalization rate (following a visit to the emergency department for suspected COVID-19) across all age groups increased significantly during the three study periods: it was 30.1% (first wave), 33.9% (second wave), and 47.2% (third wave).

A marked excess mortality (all causes) was observed during the three periods, with excess mortality estimated at +67% (period 1), +14% (period 2), and +15% (period 3) in Île-de-France.
Between March 2020 and May 2021, 25,700 COVID-19 deaths occurred in healthcare facilities, 21% of which were recorded in long-term care facilities.

The downward trends observed in incidence rates and hospital indicators are consistent with the upward trend in vaccination coverage across all age groups starting in week 52 of 2020.

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