Understanding the immune responses elicited by SARS-CoV-2 infection is critical in terms of protection against reinfection and, thus, for public health policy and vaccine development for COVID-19. In this study, using either live SARS-CoV-2 particles or retroviruses pseudotyped with the SARS-CoV-2 S viral surface protein (Spike), we studied the neutralizing antibody (nAb) response in serum samples from a cohort of 140 SARS-CoV-2 qPCR-confirmed infections, including patients with mild symptoms and also more severe forms, including those that required intensive care. We show that nAb titers correlated strongly with disease severity and with anti-spike IgG levels. Indeed, patients from intensive care units exhibited high nAb titers; conversely, patients with milder disease symptoms had heterogeneous nAb titers, and asymptomatic or exclusive outpatient-care patients had no or low nAbs. We found that nAb activity in SARS-CoV-2-infected patients displayed a relatively rapid decline after recovery compared to individuals infected with other coronaviruses. Moreover, we found an absence of cross-neutralization between endemic coronaviruses and SARS-CoV-2, indicating that previous infection by human coronaviruses may not generate protective nAbs against SARS-CoV-2. Finally, we found that the D614G mutation in the spike protein, which has recently been identified as the current major variant in Europe, does not allow neutralization escape. Altogether, our results contribute to our understanding of the immune correlates of SARS-CoV-2-induced disease, and rapid evaluation of the role of the humoral response in the pathogenesis of SARS-CoV-2 is warranted.

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This study investigated the relation between working conditions, in terms of physical and psychological demand, and upper-limb and neck musculoskeletal disorders (ULNMD) in female staff working in direct contact with the elderly in nursing homes. A cross-sectional survey was conducted in 105 nursing homes in France. Data on nursing-home working conditions were collected by questionnaire from occupational physicians and by self-administered questionnaire from staff. Psychosocial demand at work was assessed on Siegrist’s questionnaire and ULNMD on the Nordic questionnaire. 2,328 employees were included: 628 housekeepers, 1,372 nursing assistants and 328 nurses. During the previous 12 months, 50% of the subjects (1,160) had presented with a musculoskeletal complaint concerning the neck, 38% (881) the shoulders, 10% (246) the elbows and 22% (520) the wrists. 9% (219) reported effort/reward imbalance on the 2004 Siegrist questionnaire and 42% were in a situation of over-commitment. ULNMD complaints were associated not only with physical occupational factors but also with psychosocial factors (effort/reward imbalance and over-commitment), both before and after adjustment on individual and occupational factors. Prospective studies are needed to clarify the causal role of occupational, including, organizational, psychosocial factors in ULNMD outcomes. Preventive approaches should take account of both physical and psychosocial occupational factors.

Background: Exercise therapy is recommended to treat non-specific low back pain (LBP). Home-based exercises are promising way to mitigate the lack of availability of exercise centers. In this paper, we conducted a systemic review and meta-analysis on the effects of home-based exercise on pain and functional limitation in LBP. Method: PubMed, Cochrane, Embase and ScienceDirect were searched until April 20th, 2021. In order to be selected, studies needed to report the pain and functional limitation of patients before and after home-based exercise or after exercise both in a center and at-home. Random-effect meta-analyses and meta-regressions were conducted. Results: We included 33 studies and 9588 patients. We found that pain intensity decreased in the exclusive home exercise group (Effect size = −0.89. 95% CI −0.99 to −0.80) and in the group which conducted exercise both at-home and at another setting (−0.73. −0.86 to −0.59). Similarly, functional limitation also decreased in both groups (−0.75. −0.91 to −0.60, and −0.70, −0.92 to −0.48, respectively). Relaxation and postural exercise seemed to be ineffective in decreasing pain intensity, whereas trunk, pelvic or leg stretching decreased pain intensity. Yoga improved functional limitation. Supervised training was the most effective method to improve pain intensity. Insufficient data precluded robust conclusions around the duration and frequency of the sessions and program. Conclusion: Home-based exercise training improved pain intensity and functional limitation parameters in LBP.