Key Points

• In Week 12 (March 22–28, 2021), epidemiological indicators of SARS-CoV-2 circulation in Île-de-France showed a marked increase. The levels reached during this third wave of the epidemic by most indicators (incidence rate, emergency room visits, hospital indicators) exceeded the peak values observed during the second wave in October–November 2020.

• The incidence rate continued to rise sharply in Week 12 in Île-de-France, reaching 642 cases per 100,000 inhabitants. The increase was marked in all departments of the region and across all age groups, with the exception of those aged 75 and older, among whom the increase was very limited. The positivity rate, meanwhile, remained stable in Week 12.

• The rise in epidemiological indicators in Île-de-France was reflected in consultations for acute respiratory infections within the Sentinelles network, in SOS Médecins calls, and in emergency room visits for “suspected COVID-19,” all of which saw an increase in Week 12.

• The strain—already very high for several weeks on the hospital system in Île-de-France—intensified as the number of new hospitalizations and admissions to critical care continued to rise sharply. The rise in these hospital indicators reflects the actual increase in the number of SARS-CoV-2 infections as well as a possible increase in case severity linked to the predominant circulation of variants of concern suspected of being more transmissible and causing more severe infections. The age of patients admitted to critical care appears to have been shifting over the past several weeks, with a trend toward younger patients.

• At the same time, single-dose vaccination coverage in Île-de-France continued to rise, in line with the vaccination strategy, reaching 10.7% of the general population.

• The regional epidemiological situation is likely to worsen further in the coming weeks. Maintaining the systematic adoption of preventive measures remains essential in the current context.