Nationwide, the incidence rate was declining among younger age groups and showing signs of stabilizing among those aged 60 and older. In France, as of October 5, 2021, 75.2% of the population had received at least one dose of the vaccine, and 72.9% were fully vaccinated. As adherence to preventive measures has waned, vaccination combined with other preventive measures (adherence to preventive measures, limiting high-risk contacts, and self-isolation in the event of symptoms, a confirmed infection, or contact with a confirmed case) remains essential to maintaining the current favorable trend in the epidemic.

The public health situation continues to improve overall

Nationally, in week 39, the incidence rate continued to decline, with 48 new cases per 100,000 inhabitants (-16%), or an average of 4,609 cases diagnosed per day. The incidence rate was decreasing among those under 60 and tended to stabilize among older age groups. It remained higher among adults under 50 and children. The testing rate, including antigen and PCR tests (excluding self-tests), remained very high, reaching 4,580 per 100,000 inhabitants (-3%). It was stable or decreasing in all age groups, except among 10- to 19-year-olds (5,274, +34%). The positivity rate was slightly down to 1.0% (-0.2 percentage points).

In hospitals, the decline in indicators continued, with 1,228 new hospitalizations (-23%) and 306 new admissions to intensive care (-27%). As of October 5, there were 7,157 COVID-19 patients currently hospitalized, including 1,292 in intensive care.

Slight decrease in indicators in French Guiana, which remain at very high levels

In week 39, the incidence rate in French Guiana had decreased slightly (-8%), with 494 cases per 100,000 inhabitants. This slight downward trend is observed throughout the territory but must be confirmed in the coming days. Hospitalizations across all departments were down slightly, with 85 hospitalizations in week 39 compared to 115 in week 38: this decrease mainly concerns the Cayenne hospital. However, the number of admissions to critical care remained high at 20 (compared to 23 in Week 38), reflecting the rise in confirmed cases observed two weeks earlier. This increase mainly concerns the Western Hospital, which was the sector most recently impacted by the fourth wave.

In week 39, 23.4% of the population of French Guiana was fully vaccinated. Compared to the previous week, vaccination coverage had increased very little across all age groups (less than 1%). Those aged 12–17 and those aged 75 and older were the least vaccinated, and vaccination was progressing more slowly in these age groups.

Fourth wave: fewer hospitalizations and deaths than previous waves

The fourth wave of the COVID-19 epidemic, linked primarily to the Delta variant, began in early July 2021. The incidence rate reached a first peak on July 29 (week 30), rising to 225 per 100,000 inhabitants, followed by a second peak of 248 per 100,000 inhabitants on August 12 (week 32).

Over the same period, the weekly rate of new hospitalizations peaked 20 days after the first incidence peak and 6 days after the second peak (29 and 15 days for deaths). Compared to the number of cases, the levels reached (7.9 per 100,000 for new hospitalizations and 1.1 for deaths) were lower than those observed during previous waves.

Two hypotheses can be put forward to explain the observed time lags and the reduced impact of the fourth wave on hospital admissions and deaths:

• Since vaccination is highly effective in preventing severe cases, the high vaccination coverage among older adults starting in late June may have significantly reduced the occurrence of severe cases in this population, and consequently, the number of hospitalizations and deaths. While less effective in curbing viral transmission, vaccination may also have helped slow the spread of SARS-CoV-2.

• Furthermore, the virus initially circulated primarily among young adults, amid reduced adherence to preventive measures in late June 2021: during this fourth wave, 80% of confirmed cases were under the age of 50 (vs. 61% between September 2020 and June 2021). Younger people, who were also largely unvaccinated at that time, were therefore the most affected by SARS-CoV-2, while presenting a lower risk of hospitalization. Viral circulation then spread to older adults, who are more likely to develop severe forms of the disease, leading to a second peak in incidence, followed by a peak in hospitalizations.

More than 50 million French people have received a first dose of the vaccine

On October 5, the estimated vaccination coverage in France based on Vaccin Covid was 75.2% (50,482,515) for at least one dose and 72.9% (48,911,033) for full vaccination. Among those aged 12 and older, 50,462,348 had received at least one dose (87.3%) and 48,897,142 (84.6%) were fully vaccinated.

As of October 5, 93.5% of residents in nursing homes (residential care facilities for dependent elderly individuals) or long-term care units had received at least one dose of the vaccine (91.4% were fully vaccinated). Among private healthcare professionals, vaccination coverage continues to rise: 96.0% had received at least one dose and 94.5% were fully vaccinated.