We adopted the WHO’s definition of post-COVID-19 condition—which had been used in the first study conducted in early 2022—in order to compare the situation in France before and after the major waves of SARS-CoV-2 infection linked to the Omicron variant. To compare our results with those from the United Kingdom and the United States, we also used the definitions from those two countries. Furthermore, to assess the burden of long COVID more precisely, we distinguished several forms of post-COVID-19 condition based on the level of impact (severe, moderate, or no impact) of the selected symptoms on daily activities. Finally, we asked survey participants whether they “believed they had experienced a long-haul form of COVID-19” (reported long COVID or perceived long COVID).

The agreement between the categorizations derived from the different definitions was found to be low or moderate, with Kappa coefficients (ranging from 0 for agreement due solely to chance to 1 for perfect agreement) varying from 0.18 to 0.59. For example, 47% and 29% of individuals who met the criteria of the U.S. (National Center for Health Statistics, US-NCHS) and UK (Office for National Statistics, UK-ONS) definitions, respectively, also met the WHO’s definition of post-COVID-19 condition. Similarly, less than half (43%) of those meeting the WHO’s definition of post-COVID-19 condition believed they had had long COVID. These discrepancies, which affected both genders and all age groups, led us to present prevalence estimates according to the various definitions used to date in population-based studies. The WHO definition of post-COVID-19 condition offers the advantage of distinguishing different levels of symptom impact on activities of daily living.

The prevalence of post-COVID-19 conditions, as defined by the WHO, was estimated at 4.0% of the French adult population, and at 2.4% and 1.2%, respectively, when considering cases with moderate and severe impacts on people’s daily lives. Among those with post-COVID-19 conditions, 31% had had the condition for more than twelve months, and 22% for more than eighteen months. Furthermore, the reported prevalence of long COVID was 7.1%, and 7.6% and 13.4%, respectively, using the U.S. and U.K. definitions.

It was higher among women (5.4%) and lower among older adults (2.2% for those over 65 and 1.7% for those over 75) and among people living alone (2.5%). These differences were observed across all definitions used. They primarily reflect higher SARS-CoV-2 exposure among women and lower exposure among older adults and those living alone.

Among people who had been infected with SARS-CoV-2 more than three months prior, the prevalence of post-COVID-19 condition according to the WHO definition was 8%, ranging from 5.3% (men) to 10.2% (women), 14.9% (job seekers), and 18.6% (following hospitalization for COVID-19); 21% of these individuals had been infected during the Delta variant wave and 53% during the Omicron waves.

While the prevalence of post-COVID-19 conditions remained at 4% in the general population between the beginning and end of 2022, the prevalence of post-COVID-19 conditions calculated among participants reporting at least one infection, however, dropped significantly: from 30% observed at the beginning of 2022 to 8% by the end of the year. The Omicron variants of 2022 (or their occurrence in vaccinated individuals) have indeed been associated, in several studies, with a lower risk of post-COVID-19 condition than previous variants. This explains why the prevalence of long COVID in the general population remained stable (4%), while the proportion of the French population infected with SARS-CoV-2 rose from 13% to 48% between the beginning and end of 2022 (infections lasting more than three months).

Our analyses have identified numerous and varied risk factors for long COVID, including demographic, social, occupational, medical (comorbidities), behavioral, and perceptual factors, as well as those related to SARS-CoV-2 infection. This multiplicity of factors suggests that this condition should not be viewed solely as a direct complication of SARS-CoV-2 infection, but rather understood and represented within a broad network of contextual, medical, psychological, occupational, and social factors that increase an individual’s risk of long COVID, beyond the infection itself. In addition to vaccination and certain protective behaviors against SARS-CoV-2 infection, these contextual factors should be given greater consideration in strategies aimed at reducing the burden of long COVID in the population.

Analyses are still underway to clarify the condition’s impact on quality of life and to identify population groups—whether clinical (identifiable by specific symptoms) or sociodemographic—at risk of severe deterioration in quality of life.

Despite the stabilization of prevalence in France in 2022, the issue of epidemiological surveillance of long COVID—and particularly post-COVID-19 conditions—remains, although it has become challenging amid a sharp decline in the use of SARS-CoV-2 testing. The latest prevalence estimates from the United States, which has continued monthly surveillance of long COVID, show that the phenomenon is not on the decline as of early 2024. The need for follow-up or epidemiological surveillance is particularly relevant for prolonged cases (31% of cases) and those whose symptoms have a significant or very significant impact on daily activities (30%), and likely on healthcare and social protection systems.