A monocentric prospective study was conducted. The study was settled in a public nursing home located in the Ile de France region in France, accounting for 66 beds. The entire population of residents was followed from March 17th, 2020 to June 11th, 2020 after a member of the health care personnel had been tested positive to SARS-Cov2 from nasopharyngeal swab on March 16th, 2020 (positive result received on March 17th, 2020).
The study was conducted in accordance with Declaration of Helsinki and national and institutional standards. According with the current French legislation, approval by the local ethic committee was not demanded because a non-interventional research was conducted; meaning that all procedures and drugs administrated did not differed from daily clinical practice [9, 10]. Patients were informed about the inclusion in a non-interventional retrospective study. No patient or legal representative expressed opposition for the inclusion in this study.
After the first confirmed COVID-19 case among health care personnel, the first three consecutive symptomatic members of health care personnel were tested and they resulted positive to SARS-Cov2. These results justified the prosecution of the extraordinary measures, the surveillance for the rest of nursing home population (residents and health care personnel) and the reinforcement of the nursing staff. Subsequently, test for SARS-Cov2 was not systemically proposed to members of health care personnel and SARS-Cov2 molecular test was only administrated according to medical decision case by case. Probable COVID-19 cases among health care personnel were systemically confined at home.
During the time-frame analysed, all residents who developed COVID-19 symptoms after June 17th, 2020 were classified as “suspected cases” and they were isolated with implementation of contact and air precautions and room confinement, according with recommendations of the Health Regional Agency (Agence Régionale de Santé ou ARS) . All suspected cases were tested negative for influenza virus infection by rapid flu test. Only one suspected case was tested for COVID-19 by nasopharyngeal swab and classified as “confirmed case” after positive result of SARS-Cov2 PCR, according with International definition . The patient was randomly selected among the first four suspected cases with the purpose of identifying a possible cluster of COVID-19 and justifying the continuation of isolation for suspected cases and surveillance for the rest of nursing home population (residents and health care personnel). No other molecular tests were performed among nursing home residents because of the necessity of SARS-Cov2 PCR sparing as a consequence of the lack of reagents in the entire French territory and prioritisation for in-hospital diagnosis. Once available, serology test was performed retrospectively in the entire resident population at the end of the study. Serology test were performed from June 8th, 2020 to June 11th, 2020 using the Roche® SARS-CoV-2 assay .
All COVID-19 suspected cases were re-classified as “probable cases” according with the French survey protocol among nursing homes. This protocol defines probable case not only in presence of acute respiratory illness or fever (and no other aetiology fully explains the clinical presentation) but also in presence of any other symptom compatible with COVID-19 (and no other aetiology fully explains the clinical presentation). According with this protocol all probable cases were signalled to ARS . The following signs and symptoms were used for the definition of probable case: fever, severe respiratory distress requiring oxygen therapy, cough, conjunctivitis, nasal congestion, abnormal pulmonary noise at chest examination, diarrhoea, abdominal pain, fatigue, fall, neurologic troubles, lymphopeniain the complete blood count [14–17]. Fall and neurologic troubles were included among symptoms because they could reveal a marked asthenia. Sensitivity and sensibility of diagnosis based only on symptoms were calculated using serology as reference.
At the end of the study period, patients were distributed in groups according to the following criteria: i) presence of COVID-19 symptoms (symptomatic probable COVID-19 case group and asymptomatic resident group); ii) SARS-Cov2 serology results (seropositive resident group and seronegative resident group).
Residents’ files were analysed to collect the following personal parameters and co-morbidities: age, gender, grade of autonomy, not normal nutritional status (obesity or underweight), 2019–2020 seasonal flu vaccination, arterial hypertension, heart failure, atrial fibrillation, ischemic heart disease, thromboembolic venous disease, chronic obstructive pulmonary disease, solid or hematologic neoplasia, chronic kidney disease and diabetes. For the grade of autonomy, the autonomy, gerontorology, iso-resources group (autonomie, gerontology groupe iso resources or AGGIR) panel was used because it is the actual legal instrument for evaluating autonomy in aged people in France. According to this panel, the minimal AGGIR grade 1 is given to elderly patients who are confined at bed and needing a continuous surveillance while the maximal AGGIR grade 6 is given to patients with preserved autonomy . Chronic kidney disease was defined for estimated glomerular filtration rate < 60 ml/min . For nutritional status, obesity and underweight were defined for values of body mass index (BMI) > 24.9 and BMI < 18.5, respectively . Also, data about the following co-medications were collected: loop diuretics, thiazide diuretics, α-blocker antihypertensive drugs, calcium channel blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, β-blockers, insulin, metformin and other anti-diabetic drugs.
The following analysis were performed: i) chronologic description of new probable cases and deaths from March 17th, 2020 to June 11th, 2020 among residents and health care personnel; ii) sensitivity and specificity calculation for diagnosis based only on symptoms; iii) description of COVID-19 symptoms in probable cases among residents; iv) between-group (probable COVID-19 cases among residents vs asymptomatic residents) comparison of personal parameters, co-morbidities and co-medications; v) between-group (seropositive resident group vs seronegative resident group) comparison of personal parameters, co-morbidities and co-medications.
The following statistic tests were performed: χ2-test for qualitative variables and Student’s T-test for quantitative variables. Quantitative variables were presented in the text as mean values. R, the language for statistical computing (Vienna, Austria, https://www.r-project.org/) was used to perform all statistical analysis. Nominal statistical significance was set at p < 0.050.