COVID-19 Epidemiological Update, March 18, 2021. Already at high levels, viral circulation continues to rise, exacerbating hospital strain, which is critical in some regions

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Published on 19 March 2021

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Published weekly, the epidemiological update on COVID-19 surveillance provides a detailed analysis of the indicators established by Santé publique France and its network of partners to track the progression of the epidemic and guide public policy decisions. In week 10, all indicators—already at high levels—were on the rise, with a 14% increase in the number of new infections. Pressure on the hospital system continues to mount and is critical in certain regions. There has been a slight increase in the proportion of hospitalizations and admissions to intensive care units among young adults, reflecting the rise in SARS-CoV-2 infections in the 15–75 age group and a possible increase in case severity linked to the predominant circulation of variants of concern. Indicators of viral circulation and hospitalization among those aged 75 and older continue to decline, reflecting the protective effect of the vaccination coverage achieved in this population. In this context, adherence to individual and collective preventive measures and the acceleration of vaccination in the coming weeks remain major challenges in countering these unfavorable trends.

Virus transmission, already high, is on the rise in nearly all metropolitan areas

The number of new cases nationwide increased by 14% in Week 10 (March 8–14). There were 169,470 new confirmed cases, averaging 24,210 confirmed cases per day. The increase in incidence was observed across all age groups except for those aged 75 and older, where it remained stable.

Île-de-France, Hauts-de-France, and Provence-Alpes-Côte d’Azur remain the hardest-hit regions in Week 10, with the highest incidence rates (above 300 per 100,000 inhabitants and above 400 for Île-de-France), as well as the highest rates of hospitalizations and intensive care admissions. It should be noted that in Île-de-France, the incidence rate rose sharply: 426 per 100,000 inhabitants vs. 354 in Week 9, an increase of 20%.

In mainland France, estimates of the effective reproduction number (R_e) calculated from the three data sources were significantly greater than 1: virological data (RT-PCR and antigen tests, SI-DEP) (1.12), emergency department visits (1.05), and hospitalizations of COVID-19 patients (SIVIC) (1.02).

Severe strain due to the increase in patients in hospitals and critical care units

The number of hospitalized COVID-19 patients in France remains very high, with 25,552 people hospitalized as of March 16, while the weekly hospitalization rate rose again in Week 10 (+5%). The rate of admissions to critical care units continued to rise more sharply in Week 10 (+11% compared to Week 09). This trend is reflected in a steady increase in the number of people currently hospitalized in critical care units: as of March 16, 2021, 4,260 patients were hospitalized there (compared to 3,928 on March 9, an increase of 8.5%).

There is evidence of a possible increase in case severity linked to the widespread circulation of variants of concern. Indeed, starting in Week 4, an increase in the ratio of critical care admissions to the number of symptomatic cases was observed among patients aged 15 to 64, suggesting a possible increase in disease severity among these patients, which is more pronounced among young adults (ages 15–44). Among the latter, however, the rate of admission to critical care remains low compared to that of older age groups.

The 20I/501Y.V1 (UK) variant now accounts for 72% of screened tests

According to indicators generated from SI-DEP, at the national level in Week 10:

72.0% corresponded to a suspected 20I/501Y.V1 (UK) variant, compared to 65.8% in week 09
5.0% were suspected cases of the 20H/501Y.V2 (ZA) or 20J/501Y.V3 (BR) variants, compared to 4.9% in week 09, respectively.

These variants were detected in all metropolitan regions. The proportion of suspected cases of the 20I/501Y.V1 (UK) variant was greater than 50% (among screened positive tests) in 91 metropolitan departments (compared to 79 departments in week 09).

The results of the Flash#4 survey, based on whole-genome sequencing, confirm the regional heterogeneity of variant circulation among the 12 regions represented in this survey and an increase in their prevalence in most of these regions. Among 1,572 SARS-CoV-2-positive samples analyzed, from 98 public and private medical laboratories, 63.2% were due to the 20I/501Y variant.V1, 5.2% were due to the 20H/501Y.V2 variant, and 0.1% to the 20J/501Y.V3 variant.

Genomic surveillance: an emerging variant of clade 20C in Brittany

Variant surveillance is conducted using samples representative of viruses circulating in the population and is based on three principles:

A real-time snapshot of the circulation of variants of interest across the region. Analysis of screening data via SI-DEP, which enables daily monitoring of suspected cases of known variants of interest and an assessment of their spread throughout the region.
Identification and characterization of the emergence of new variants via specific FLASH studies involving the sequencing of a random sample of specimens (prior to any screening)
Enhanced epidemiological surveillance

According to a virological and epidemiological risk analysis (transmissibility, pathogenicity, or immune escape) conducted by the CNR and Santé publique France, variants are classified into three levels: variants of interest (whose impact on the epidemic is demonstrated and justifies specific surveillance and management measures at the national level); variants to monitor (whose impact is potential and for which the CNR is implementing national and international monitoring as well as specific virological analyses to assess their characteristics); other identified variants (which do not present any risk characteristics).

The new variant (derived from Clade 20C) detected as part of a cluster at a hospital in the Côtes d’Armor region is classified as a variant to monitor. To date, there is no evidence that this variant is more transmissible or causes more severe disease, but the emergence of this variant is under investigation and the situation is being monitored across the region through specific surveillance.

More than 1.2 million people have received their first dose of the vaccine since March 9, 2021

As of March 16, 2021:

5,445,157 people have received at least one dose of the COVID-19 vaccine, and 2,295,732 people have been fully vaccinated with two doses, representing 8.1% and 3.4% of the population in France, respectively.
89.4% of residents in nursing homes (Ehpad) or long-term care facilities (USLD) have received a first dose of the vaccine, and 68.5% have received two doses. Additionally, 50.0% of healthcare workers in nursing homes or long-term care facilities have received at least one dose of the vaccine.

Given the high level of viral circulation and significant strain on the healthcare system, the strict enforcement of all individual and collective measures is more essential than ever. It remains crucial that anyone exhibiting symptoms suggestive of COVID-19 immediately self-isolate and undergo a diagnostic test as soon as possible. The use of digital tools (TousAntiCovid) is recommended to strengthen contact tracing and rapid isolation measures.

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