In week 21 (May 23–29, 2022), the spread of SARS-CoV-2 continued to slow, though at a less pronounced rate than in previous weeks. The decline in the incidence rate was smaller in certain age groups, and a trend toward stabilization was observed in some regions. At the same time, the number of hospital admissions continued to decrease. In the overseas territories, virological indicators remained very high and continued to rise in Martinique.

The BA.2 sublineage of the Omicron variant was by far the most prevalent, accounting for 94% of interpretable sequences in the Flash S20 survey (May 16). An increase in the presence of the L452 mutation in screening tests (12% in S21) was again observed this week in connection with the rise of certain Omicron sublineages, including BA.4 and BA.5. This is further confirmed by sequencing data, which showed an increase in the detection of these sublineages. The detection of BA.4 and BA.5 in Flash surveys is increasing: 0.8% for BA.4 and 5% for BA.5 in Flash S20-2022, compared to 0.5% and 1.5% in Flash S19-2022. In South Africa, where BA.4 and BA.5 were initially detected, the peak of the epidemic wave associated with these two sublineages passed in mid-May, and its impact was very moderate. Additional information is available in the variant risk analysis dated May 18, 2022.

The XD recombinant, detected at low levels since early January 2022, accounts for less than 0.1% of interpretable sequences in Flash S19 and was not detected during Flash S20.

As of May 30, only 32.4% of those aged 60–79 and 27.5% of those aged 80 and older who were eligible for the second booster dose had actually received it. Given that SARS-CoV-2 continues to circulate, adherence to preventive measures remains essential to maintaining the favorable trend in the epidemic. Furthermore, vaccination efforts must continue, particularly in areas where the virus remains widespread, as well as for the second booster dose among eligible individuals, especially those who are vulnerable. Maintaining other recommended measures is also necessary in the event of symptoms, a positive test result, or exposure to a confirmed case.