Feasibility of large-scale population testing for SARS-CoV-2 detection by self-testing at home.

The simplicity and low cost of rapid point-of-care tests greatly facilitate large-scale population testing, which can contribute to controlling the spread of the COVID-19 virus. We evaluated the applicability of a self-testing strategy for SARS-CoV2 in a population-based, cross-sectional study in Cantabria, Spain, between April and May 2020. For the self-testing strategy, participants received the necessary material for the self-collection of blood and performance of a rapid antibody test using lateral flow immunoassay at home without the supervision of healthcare personnel. A total of 1,022 participants were enrolled. Most participants correctly performed the COVID-19 self-test the first time (91.3% [95% CI 89.4-92.9]). Only a minority of the participants (0.7%) needed the help of healthcare personnel, while 6.9% required a second kit delivery, for a total valid test result in 96.9% of the participants. Incorrect use of the self-test was not associated with the educational level, age over 65, or housing area. Prevalence of IgG antibodies against SARS-CoV2 for subjects with a valid rapid test result was 3.1% (95% CI 2.2-4.4), similar to the seroprevalence result obtained using a conventional approach carried out by healthcare professionals. In conclusion, COVID-19 self-testing should be considered as a screening tool.

Socio-economic factors do also matter: comments on the article "can climatic factors explain the differences in COVID-19 incidence and severity across the SPANISH regions?: an ecological study".

Phosri et al., commented on our previous study about the influence of climate variables at the beginning of the SARS-CoV-2 pandemic in Spain. They showed the impact of the association of gross domestic product (GDP) with the cumulative COVID-19 incidence per 105 inhabitants in our country and the rise of several methodologic issues. Here we discussed the main advantages and disadvantages of ecological studies and we advocate to test the hypothesis created in this type of studies using individual-level research designs.

Vitamin D Status in Hospitalized Patients with SARS-CoV-2 Infection.

BACKGROUND: The role of vitamin D status in COVID-19 patients is a matter of debate. OBJECTIVES: To assess serum 25-hydroxyvitamin D (25OHD) levels in hospitalized patients with COVID-19 and to analyze the possible influence of vitamin D status on disease severity. METHODS: Retrospective case-control study of 216 COVID-19 patients and 197 population-based controls. Serum 25OHD levels were measured in both groups. The association of serum 25OHD levels with COVID-19 severity (admission to the intensive care unit, requirements for mechanical ventilation, or mortality) was also evaluated. RESULTS: Of the 216 patients, 19 were on vitamin D supplements and were analyzed separately. In COVID-19 patients, mean ±â€…standard deviation 25OHD levels were 13.8 ±â€…7.2 ng/mL, compared with 20.9 ±â€…7.4 ng/mL in controls (P < .0001). 25OHD values were lower in men than in women. Vitamin D deficiency was found in 82.2% of COVID-19 cases and 47.2% of population-based controls (P < .0001). 25OHD inversely correlates with serum ferritin (P = .013) and D-dimer levels (P = .027). Vitamin D-deficient COVID-19 patients had a greater prevalence of hypertension and cardiovascular diseases, raised serum ferritin and troponin levels, as well as a longer length of hospital stay than those with serum 25OHD levels ≥20 ng/mL. No causal relationship was found between vitamin D deficiency and COVID-19 severity as a combined endpoint or as its separate components. CONCLUSIONS: 25OHD levels are lower in hospitalized COVID-19 patients than in population-based controls and these patients had a higher prevalence of deficiency. We did not find any relationship between vitamin D concentrations or vitamin deficiency and the severity of the disease.

Can climatic factors explain the differences in COVID-19 incidence and severity across the Spanish regions?: An ecological study.

BACKGROUND: Environmental factors play a central role in seasonal epidemics. SARS-CoV-2 infection in Spain has shown a heterogeneous geographical pattern This study aimed to assess the influence of several climatic factors on the infectivity of SARS-CoV-2 and the severity of COVID-19 among the Spanish Autonomous Communities (AA.CC.). METHODS: Data on coronavirus infectivity and severity of COVID-19 disease, as well as the climatic variables were obtained from official sources (Ministry of Health and Spanish Meteorological Agency, respectively). To assess the possible influence of climate on the development of the disease, data on ultraviolet radiation (UVR) were collected during the months before the start of the pandemic. To analyze its influence on the infectivity of SARS-CoV-2, data on UVR, temperature, and humidity were obtained from the months of highest contagiousness to the peak of the pandemic. RESULTS: From October 2019 to January 2020, mean UVR was significantly related not only to SARS-CoV-2 infection (cumulative incidence -previous 14 days- × 105 habitants, rho = - 0.0,666; p = 0.009), but also with COVID-19 severity, assessed as hospital admissions (rho = - 0.626; p = 0.017) and ICU admissions (rho = - 0.565; p = 0.035). Besides, temperature (February: rho = - 0.832; p < 0.001 and March: rho = - 0.904; p < 0.001), was the main climatic factor responsible for the infectivity of the coronavirus and directly contributed to a different spread of SARS-CoV-2 across the Spanish regions. CONCLUSIONS: Climatic factors may partially explain the differences in COVID-19 incidence and severity across the different Spanish regions. The knowledge of these factors could help to develop preventive and public health actions against upcoming outbreaks of the disease.