In Week 13 (March 28–April 3), SARS-CoV-2 transmission remained at a very high level throughout the country. While the rise in the incidence rate was slowing, new hospital and intensive care admissions were increasing. This trend was, however, uneven: the incidence rate was decreasing among those under 20. Similarly, at the regional level, incidence appeared to be stabilizing in certain metropolitan areas. Changes in incidence and testing rates should be interpreted with caution in the coming weeks, due to the increasingly frequent use of self-tests, which are not included in SI-DEP indicators unless confirmed by an antigen test or RT-PCR. The increase in the number of intensive care admissions must be closely monitored, given the flu epidemic, which is contributing to increased pressure on hospitals. As of April 4, 83.3% of those aged 65 and older had received a booster shot, and only 6.6% of those aged 80 and older had received a second booster dose. Given the current high circulation of SARS-CoV-2 and influenza viruses, as well as their impact on the healthcare system and hospitals, adherence to preventive measures (wearing masks in enclosed spaces or at large gatherings, handwashing, and ventilating enclosed spaces) is essential, particularly to protect vulnerable individuals. Vaccination efforts, including the second booster dose, must also continue among eligible populations. Similarly, adherence to other recommended measures is necessary in the event of symptoms, a positive test result, or exposure to a high-risk contact.

More than 135,000 new cases diagnosed on average per day

Nationally, the incidence rate was 1,434 cases per 100,000 inhabitants in week 13 (+7% vs. week 12). This rate continued to rise among adults for the fourth consecutive week but declined among those under 20. It nevertheless remained above 1,000 per 100,000 in all age groups except those under 10 years of age. The testing rate followed the same trend as the incidence rate (+5%). The positivity rate therefore changed little in week 13 but remained very high at 31.0% (+0.5 percentage points). It was declining among those under 20, supporting the hypothesis of a decrease in SARS-CoV-2 circulation in this age group, to be confirmed in the coming weeks. The effective reproduction number (Rt) remained above 1 (1.21), indicating that virus circulation was still on the rise.

In mainland France, the incidence rate continued to rise in all regions, with the exception of Brittany (1,779, -2%), Grand Est (1,581, -5%), and Nouvelle-Aquitaine (1,128, -2%), where it stabilized. All regions had an incidence rate above 1,000 per 100,000. The highest rates were observed in Corsica (1,979, +13%) and Brittany. In the overseas territories, the incidence rate was highest and still rising in Réunion (1,503, +12%). It was decreasing in Guadeloupe (811, -14%) and Martinique (735, -31%).

Continued rise in new hospital admissions and critical care admissions

Nationally, the number of new hospital admissions continued to rise (+7%) in Week 13. This increase was more pronounced for admissions to critical care units, a trend that began in Week 12: 795 (+14%) in Week 13 (unconsolidated data) and 697 (+12%) in Week 12. The number of deaths in hospitals and long-term care facilities began to rise again in Week 13, despite data still being unconsolidated (+2%).

In mainland France, critical care admission rates were rising in all regions except Hauts-de-France, Île-de-France, and Normandy, where they were stable or slightly declining. The highest rates were observed in Corsica (20.0, +23%), Normandy (18.8, +18%), Brittany (18.3, +10%), and Bourgogne-Franche-Comté (18.1, +26%). In the overseas territories, the rate of new hospitalizations remained highest in Réunion (11.5), while the rate of new admissions to intensive care was again highest in Guadeloupe (1.9).

Omicron remains dominant, with the BA.2 sublineage now accounting for 92% of sequences

Sequencing data confirm the dominance of Omicron in France. Omicron accounted for more than 99.9% of interpretable sequences in the Flash S12 survey (March 21).

The BA.2 sublineage of the Omicron variant was predominant in France, accounting for 92% of the 2,506 sequences in the Flash S12 survey (March 21). The rise of BA.2 at the expense of BA.1 was observed throughout mainland France and in the overseas departments and regions (DROM). While BA.2 has been shown to be more transmissible than BA.1, the two sublineages are similar in terms of immune evasion and disease severity.

The XD recombinant has been classified as a variant under monitoring (VUM) since the variant risk analysis of March 23, 2022, due to its genetic characteristics derived from the parent variants of concern (VOCs) (Delta AY.4 and Omicron BA.1). As of April 4, 65 sequences had been detected in France. These sequences correspond to cases from several metropolitan regions. The XD recombinant accounts for less than 0.1% of interpretable sequences from the Flash S01 (January 3) to Flash S11 (March 14) surveys, and was not detected during the Flash S12 survey.

6.6% of those aged 80 and older have received a second booster dose

As of April 4, 2022, the estimated vaccination coverage in the general population was 79.5% for a complete primary vaccination series and 58.7% for the booster dose. Vaccination coverage for the booster dose was 73.3% among those aged 18 and older and 83.3% among those aged 65 and older. In addition, 9.5% of children aged 10 to 11 had received a first vaccine dose (3.2% for those aged 5 to 9). Vaccination coverage for the second booster dose was 6.6% among those aged 80 and older. For residents in nursing homes or long-term care facilities, 93.5% had received a complete primary vaccination series, 71.3% had received a booster dose, and 2.7% had received a second booster.

Vaccination coverage data by department are published on Géodes, and data regarding the second booster dose have also been published there since April 7, 2022.