ABSTRACT
Background: A rapid increase in incidence of the SARS-CoV-2 Omicron variant in France in December 2021, while the Delta variant was prevailing since July 2021. Aim: To determine whether the risk of occurrence of a serious hospital event in adults following symptomatic SARS-CoV-2 infection differs for Omicron versus Delta. Methods: A retrospective cohort study from 06/12/2021 to 07/01/2022. The outcome was a serious hospital event (admission to intensive care unit OR admission to critical care unit OR death). Omicron and Delta symptomatic cases were matched on the week of virological diagnosis and on age. Risk was adjusted for age, sex, vaccination status, presence of comorbidity and region of residence using Cox proportional-hazards model. Results: 149,064 cases were included of which 497 had a serious hospital event (447 in the Delta arm, 50 in the Omicron arm). The risk of serious event was lower among Omicron versus Delta cases (adjusted Hazard Ratio, aHR=0.13 CI95 0.09-0.18 in 18 to 79 yo, aHR=0.30 CI95 0.17-0.54 in 80+ yo). The risk increased sharply with age and was lower in vaccinated compared to unvaccinated, without interaction between variant and vaccination status (aHR=0.15 CI95 0.11-0.19 for 18-79 yo with primary vaccination versus unvaccinated), was higher in cases with comorbidities (aHR = 3.70 CI95 2.66-5.13 fort 18-79 yo with very-high-risk comorbidity versus no comorbidity) and in males. Conclusion: This study confirms the lower severity of Omicron. The vaccine protection is essential in the elderly as they have a high risk of severe hospital events following infection with Omicron, even if much this risk is lower than with Delta.
Subject(s)
COVID-19 , DeathABSTRACT
Background In March 2020, many cases of COVID-19 were reported in three socially deprived neighbourhoods of the city of Perpignan, in the south of France, where large sedentary gypsy communities live. A study to measure seroprevalence was conducted in July 2020 to assess the level of contamination in these neighbourhoods after the first wave of the pandemic, and to identify factors associated with seropositivity. Methods SCoPe is a cross-sectional survey conducted in selected persons aged six years old and over living in three neighbourhoods in Perpignan. Households were selected by systematic sampling and participants by random sampling. Collected blood samples were tested for SARS-CoV-2 IgG and IgM antibodies using the EIecsys(R) immunoassay to target the coronavirus's spike protein. Antibody seroprevalence was estimated from weighted data and associated factors were investigated using multivariate logistic regression. Results The seroprevalence of anti-SARS-CoV-2 antibodies was 35.4% (95% CI: 30.2-41.0). Over a fifth of seropositive individuals (21.7% ([14.1-31.8]) did not report any COVID-19 symptom. People aged 15-64 years old were at greater risk of seropositivity than those aged 65 years or over. Obesity prevalence was 40.7% (35.8-45.8) and obese people were more likely to be seropositive (aOR=2.0 [1.1-3.8]). The risk of being seropositive was higher in households with clinical COVID-19 cases (One case: aOR=2.5 [1.3-5.0]). In the neighbourhood with the highest measured seroprevalence, people living in a dwelling with 1-2 rooms had a higher risk of being seropositive than those living in a 4-room house (aOR=2.8 [1.2-6.3]). Working during the lockdown was associated with a lower risk of seropositivity (aOR=0.2 [0.03-1.0]). Conclusion Transmission prevalence of the SARS-COV-2 virus in this vulnerable population was very high during the COVID-19 pandemic's first wave. Our results highlight the need to strengthen and adapt preventive measures by taking into account all social determinants of health, especially housing conditions.
Subject(s)
COVID-19ABSTRACT
France has been heavily affected by the SARS-CoV-2 epidemic and went into lockdown on the 17th March 2020. Using models applied to hospital and death data, we estimate the impact of the lockdown and current population immunity. We find 2.6% of infected individuals are hospitalized and 0.53% die, ranging from 0.001% in those <20y to 8.3% in those >80y. Across all ages, men are more likely to be hospitalized, enter intensive care, and die than women. The lockdown reduced the reproductive number from 3.3 to 0.5 (84% reduction). By 11 May, when interventions are scheduled to be eased, we project 3.7 million (range: 2.3-6.7) people, 5.7% of the population, will have been infected. Population immunity appears insufficient to avoid a second wave if all control measures are released at the end of the lockdown.