To the Editor, To face the new coronavirus disease 2019 (COVID-19) pandemic, the need for early and accurate diagnosis of the disease among suspected cases quickly became obvious for effective management, and for better control of the spread of the disease in the population. Since the beginning of this disease epidemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), reverse transcriptase-polymerase chain reaction (RT-PCR) has routinely been used to confirm the diagnosis. However, several authors have pointed out the poor performance of this technique, particularly in terms of sensitivity. 1,2 Indeed, according to some authors, sensitivity could be as low as 38% 3 (ie, not better than chance). This made it necessary to find a more sensitive test, given the contagiousness of SARS-CoV-2. We, therefore, read with great interest the article published in your journal by Cassaniti et al. 4 This article deals with the diagnosis of COVID-19 by serology (immunoglobulin m/immunoglobulin G) as a complementary approach to RT-PCR to improve its sensitivity. According to Cassaniti et al 4 and Xiang et al, 5 serology is faster to implement, less expensive, easier to use, and more accessible to staff with no specific laboratory training. 5 The article describes the metrological performances of

Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website.Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

Only 8.2% of the older adults presenting in the acute phase of CHIKV have typical forms, suggesting that the most-frequent clinical presentation of CHIKV in older adults differs from that in younger individuals.

Background: Vitamin D has diverse and extensive effects on the immune system, including activating innate immunity and reducing the overactive adaptive immune response. A systematic review was performed to identify and synthesize the best available evidence on the association between vitamin D level and risk of COVID-19, adverse outcomes and possible benefits of supplementation in aged 60 years or over. Methods: A literature search was performed in PubMed© and Scopus© for all publications from inception published before 15 March 2021. Studies reporting data from aged patients on vitamin D use and COVID-19 were included. Basic science articles, editorials and correspondence were excluded. Publication year, study design and setting, characteristics of the study population were extracted. This study is registered with PROSPERO, under the number CRD42020223993. Results: In total, 707 studies were identified, of which 11 observational studies were included in the final review. Four studies compared vitamin D-supplemented COVID-19 patients to non-supplemented patients, and seven compared patients with vitamin D deficiency to patients without deficiency. In all four studies, patients with vitamin D supplementation had better rates of primary clinical outcomes (death, the severity of the disease, oxygen therapy requirement…). In studies comparing patients with vitamin D deficiency and patients without vitamin D deficiency, those without vitamin D deficiency had better primary clinical outcomes (death rate, the severity of the disease, oxygen therapy requirement, invasive mechanical ventilation need…). Conclusion: This systematic review seems to support an association between vitamin D deficiency and the risk of COVID-19 in aged people. In addition, vitamin D deficiency appears to expose these subjects to a greater risk of adverse outcomes. Because of its simplicity of administration, and the rarity of side effects, including vitamin D in preventive strategies for certain viral diseases, it appears to be an attractive option.

ObjectiveThe primary objective was to identify predictive factors of inhospital death in a population of patients aged 65 years or older hospitalised with Chikungunya virus (CHIKV) infection. The secondary aim was to develop and validate a predictive score for inhospital death based on the predictors identified.DesignLongitudinal retrospective study from January to December 2014.SettingUniversity Hospital of Martinique.ParticipantsPatients aged ≥65 years, admitted to any clinical ward and who underwent reverse transcription PCR testing for CHIKV infection.OutcomeIndependent predictors of inhospital death were identified using multivariable Cox regression modelling. A predictive score was created using the adjusted HRs of factors associated with inhospital death. Receiver operating characteristic curve analysis was used to determine the best cut-off value. Bootstrap analysis was used to evaluate internal validity.ResultsOverall, 385 patients aged ≥65 years were included (average age: 80±8 years). Half were women, and 35 (9.1%) died during the hospital stay. Seven variables were found to be independently associated with inhospital death (concurrent cardiovascular disorders: HR 11.8, 95% CI 4.5 to 30.8; concurrent respiratory infection: HR 9.6, 95% CI 3.4 to 27.2; concurrent sensorimotor deficit: HR 7.6, 95% CI 2.0 to 28.5; absence of musculoskeletal pain: HR 2.6, 95% CI 1.3 to 5.3; history of alcoholism: HR 2.5, 95% CI 1.1 to 5.9; concurrent digestive symptoms: HR 2.4, 95% CI 1.2 to 4.9; presence of confusion or delirium: HR 2.1, 95% CI 1.1 to 4.2). The score ranged from 0 to 25, with an average of 6±6. The area under the curve was excellent (0.90; 95% CI 0.86 to 0.94). The best cut-off value was a score ≥8 points, with a sensitivity of 91% (82%–100%) and specificity of 75% (70%–80%).ConclusionsSigns observed by the clinician during the initial examination could predict inhospital death. The score will be helpful for early management of elderly subjects presenting within 7 days of symptom onset in the context of CHIKV outbreaks.