In Week 12 (March 21–27), the spread of SARS-CoV-2 intensified across the country, confirming the resurgence of the epidemic for the third consecutive week. The incidence rate, which is on the rise, exceeded the threshold of 1,000 cases per 100,000 inhabitants in all metropolitan regions. The highest rates were observed among those aged 10–19 and 30–49. New hospitalizations increased while the number of deaths continued to decline. As of March 28, 83.2% of those aged 65 and older and 71.1% of residents in nursing homes or long-term care facilities had received a booster shot, with this proportion having changed little since the previous week. Given the current context of a continued acceleration in the spread of SARS-CoV-2 and influenza viruses, adherence to preventive measures (wearing masks in enclosed spaces or areas with high crowding, handwashing, and ventilating enclosed spaces) is essential for prevention, 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 120,000 new cases diagnosed on average per day

Nationally, the incidence rate exceeded the threshold of 1,000 cases per 100,000 inhabitants in week 12. This rate continued to rise (+42% from the previous week) across all age groups for the third consecutive week. The incidence rate was highest among those aged 10–19, 30–39, and 40–49 (>1,600/100,000). The effective R number (1.35) rose again. The testing rate also continued to rise (+27%). Similarly, the positivity rate was on the rise and reached 30.5%. It was highest among those aged 40–49 and 10–19, though increases were steeper among the oldest age group (50–89) as in the previous week.
In mainland France, the incidence rate continued to rise in all regions, ranging from +17% in Nouvelle-Aquitaine to +78% in Île-de-France. The highest rates were observed in Brittany (1,800, +35%) and Corsica (1,746, +41%). In the overseas territories, the incidence rate was highest and rising in Réunion (1,341, +21%). High rates were observed in Martinique (1,063, -37%) and Guadeloupe (938, -3%).

Increase in new hospitalizations and admissions to critical care

Nationally, the number of new hospital admissions increased in week 12 (+5%), and new admissions to critical care units rose slightly (+2%). The number of deaths in hospitals and long-term care facilities continued to decline. All-cause mortality remained within the usual range of fluctuation.
In metropolitan France, rates of new hospitalizations were rising in several regions, notably in Pays de la Loire, Île-de-France, Centre-Val de Loire, and Auvergne-Rhône-Alpes. In the overseas territories, the rate of new hospitalizations was highest in Réunion, where it remained stable.

The BA.2 sublineage remains dominant and accounts for 84% of sequences

Sequencing data confirm the dominance of Omicron in France. Omicron accounted for more than 99.9% of interpretable sequences in the Flash S11 survey (March 14).
The BA.2 sublineage of the Omicron variant is now the majority in France, accounting for 84% of the 2,329 sequences in the Flash S11 survey. The rise of BA.2 at the expense of BA.1 is observed throughout mainland France, but at varying levels across regions. In the overseas departments and regions (DROM), BA.2 also appears to be on the rise. While BA.2 has been shown to be more transmissible than BA.1, the two sublineages are similar in terms of immune evasion and severity.

The AY.4/BA.1 (XD) recombinant has been classified as a variant under monitoring (VUM) since the variant risk assessment of March 23, 2022. As of March 28, 63 sequences had been detected in France. These sequences correspond to cases from several regions of metropolitan France. The XD variant accounts for less than 0.1% of interpretable sequences since the Flash S01 survey, including in the Flash S11 survey (March 14). In addition, 54 confirmed (via sequencing) or suspected (linked to a confirmed case) cases of infection with the XD variant were investigated by the regional units of Santé publique France in collaboration with the CNR and the laboratories of the EMERGEN consortium. While the majority of cases had received a complete primary vaccination series (54%), including 24% who had received the first booster dose, only three cases (6%) reported a previous SARS-CoV-2 infection, which is lower than with Omicron (14% of the 468 cases investigated between November 2021 and January 2022). Compared to Omicron, the proportion of cases reporting a loss of taste or smell was higher among cases of infection with the XD variant.

More than 73% of people aged 18 and older have received a booster dose

As of March 28, 2022, the estimated vaccination coverage in the general population was 79.5% for a complete primary vaccination series and 58.6% for the booster dose. Vaccination coverage for the booster dose was 73.2% among those aged 18 and older and 83.2% among those aged 65 and older. In addition, 9.4% of children aged 10 to 11 had received a first dose of the vaccine (3.2% for those aged 5 to 9). 93.5% of residents in nursing homes or long-term care facilities had received a full primary vaccination series, and 71.1% had received a booster dose.

Following the latest recommendations regarding the second booster dose for people aged 80 and older as well as for residents in nursing homes or long-term care facilities, vaccination coverage data for the second booster dose will be published shortly.

In addition, Santé publique France is publishing an update on the surveillance of COVID-19 cases among healthcare workers in healthcare facilities and the report on the surveillance of cases of pediatric multisystem inflammatory syndrome.