Effects of Vitamin D on COVID-19 Infection and Prognosis: A Systematic Review

Vitamin D: A key player in COVID-19 immunity and lessons from the pandemic to combat immune-evasive variants

As of the 7th of July 2024, 775,754,322 confirmed cases of COVID-19, including 7,053,902 deaths worldwide, had been reported to the WHO (World Health Organization). Nevertheless, untill the 15th of July 2024, a total of 13,578,710,228 vaccine doses had been administered, with almost no country spared from COVID-19 attacks. The pathophysiology of this virus is complicated, and several symptoms require a deep understanding of the actual mechanisms. It is unclear why some patients develop severe symptoms while others do not, although literature suggests a role for vitamin D. Vitamin D plays a crucial role in the infection or in ameliorating the severity of symptoms. The mechanism of action of vitamin D and vitamin D deficiency (VDD) is well understood. VDD is associated with increased hospitalization of severely ill patients and increased levels of COVID-19-caused mortality. Recent studies suggest that vitamin D levels and genetic variations in the vitamin D receptor (VDR) gene significantly impact the severity and outcomes of COVID-19, especially in the infections caused by Delta and Omicron variants. Furthermore, VDD causes immune system dysregulation upon infection with SARS-CoV-2, indicating that vitamin D sufficiency is crucial in fighting against COVID-19 infection. The therapeutic effect of vitamin D raises interest in its potential role as a prophylactic and treatment adjunct. We evaluate the immunomodulatory effects of vitamin D and its ability to enhance the efficacy of new antiviral drugs like molnupiravir and paxlovid against SARS-CoV-2. This review discusses the role of vitamin D sufficiency and VDD in COVID-19 initiation and progression, emphasizing the molecular mechanisms by which vitamin D exerts its actions as a proactive step for the next pandemic. However, there is still no clear evidence of vitamin D's impact on prevention and treatment, leading to contradictory findings. Therefore, large-scale randomized trials are required to reach a definitive conclusion. A bibliometric analysis of publications related to vitamin D, immunity, and COVID-19 revealed a significant increase in research activity in this area, particularly in 2020-2024, underscoring the growing recognition of vitamin D's potential role in the context of the pandemic.

Serum 25-hydroxyvitamin D levels and health outcomes of hospitalization owing to COVID-19: a retrospective cross-sectional study

OBJECTIVE

We investigated the role of serum 25(OH)D (25-hydroxyvitamin D) in COVID-related health outcomes.

METHODS

We conducted a retrospective cross-sectional study using data of the National Center of Disease Control and Public Health, Georgia. We extracted patient data including length of hospital stay, transfer to the intensive care unit, requirement for oxygen therapy, treatment with glucocorticoids, and symptoms. After obtaining written informed consent, 384 individuals were enrolled. We divided participants into three groups according to 25(OH)D levels: group 1 = 25(OH)D <12 ng/mL (n = 83), group 2 = 25(OH)D 12-20 ng/mL (n = 141), and group 3 = 25(OH)D >20 ng/mL (n = 160).

RESULTS

The odds ratio (OR) for hospitalization in group 1 versus group 2 was 8.7 (95% confidence interval [CI] 3.6-21.3) and 5.6 for group 1 versus 3 (95% CI 2.7-11.9). Regarding oxygen therapy, OR = 28.41 for group 1 versus 2 (95% CI 3.7-220.5) and OR = 5.2 for group 1 versus 3 (95% CI 1.9-14.1). Regarding treatment with glucocorticoids, OR = 3.7 for group 1 versus 2 (95% CI 1.1-12.5) and OR = 8.4 for group 1 versus 3 (95% CI 1.8-40.7).

CONCLUSION

COVID-19-related morbidity was associated with decreased serum 25(OH)D levels. Future studies should investigate the potential role of vitamin D sufficiency in preventing SARS-CoV-2 infection and mortality.

High risk of malnutrition among hospitalised coronavirus disease 2019 (COVID-19) patients is associated with mortality and other clinical outcomes

INTRODUCTION

Increasing evidence indicates an association between nutritional status and Coronavirus disease 2019 (COVID-19) disease severity. The aim of the study was to describe the risk of malnutrition, body mass index (BMI) and vitamin D status of hospitalised COVID-19 patients and assess whether they are associated with duration of hospital stay, intensive care unit (ICU) admission, mechanical ventilation, and mortality.

METHODS

The study is a descriptive retrospective study of 273 patients with COVID-19 admitted to Hospital from February 2020 to March 2021. Patients were screened for risk of malnutrition using a validated screening tool. BMI was calculated from height and weight. Insufficient Vitamin D status was defined as 25(OH)vitD <50 nmol/L. Logistic regression analysis was used to assess the association between indicators of nutritional status of patients with COVID-19, and outcomes such as duration of stay >7 days, ICU admission, mechanical ventilation, and mortality. Interaction between risk of malnutrition and BMI of ≥30 kg/m2 was assessed using the likelihood ratio test with hospital stay, ICU admission, mechanical ventilation, and mortality as outcomes.

RESULTS

Screening for risk of malnutrition identified 201 (74%) patients at a medium to high risk of malnutrition. Patients defined as being at a medium or high risk of malnutrition were more likely to be hospitalised for >7 days compared to those defined as low risk (OR: 10.72; 95% CI: 3.9-29.46; p < 0.001 and OR: 61.57; 95% CI: 19.48-194.62; p < 0.001, respectively). All patients who were admitted to ICU (n = 41) and required mechanical ventilation (n = 27) were defined as having medium or high risk of malnutrition. High risk of malnutrition was also associated with increased odds of mortality (OR: 8.87; 955 CI 1.08-72,96; p = 0.042). BMI of ≥30 kg/m2 (43%) and 25(OH)vitD <50 nmol/L (20%) were not associated with duration of stay >7 days or mortality, although BMI ≥30 kg/m2 was associated with increased risk of ICU admission (OR: 7.12; 95% CI: 1.59-31.94; p = 0.010) and mechanical ventilation (OR: 8.86; 95% CI: 1.12-69.87; p = 0.038). Interactions between risk of malnutrition and BMI ≥30 kg/m2 were not significant to explain the outcomes of hospital stay >7 days, ICU admission, mechanical ventilation, or mortality.

CONCLUSION

High risk of malnutrition among hospitalised COVID-19 patients was associated with longer duration of hospital stay, ICU admission, mechanical ventilation and mortality, and BMI ≥30 kg/m2 was associated with ICU admission and mechanical ventilation. Insufficient Vitamin D status was not associated with duration of hospital stay, ICU admission, mechanical ventilation, or mortality.

Serum vitamin D3 (25-OH vit D3) concentrations and hemogram changes in calves with enzootic pneumonia

BACKGROUND

Enzootic pneumonia is an important disease complex associated with insufficient colostrum intake after birth, adverse environmental conditions, and stress. Vitamin D deficiency may be an important predisposing factor for this disease.

OBJECTIVE

This study aimed to investigate in calves with enzootic pneumonia.

METHODS

A total of 30 calves, aged 3-5 months, under the same care and feeding conditions were used. Groups were formed according to Clinical Respiratory Scoring as the group with mild/moderate enzootic pneumonia (n = 10), the group with severe enzootic pneumonia (n = 10), and the healthy control group (n = 10) without any disease. Blood samples were collected from the jugular vein of animals in all groups on Day 0; a complete blood count was performed, and serum vitamin D levels were measured using the Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method.

RESULTS

Although no statistical differences were observed in total leukocyte, lymphocyte, eosinophil, basophil, hemoglobin, and hematocrit levels between groups, statistically significant differences in blood neutrophil, monocyte, and erythrocyte counts were found between the groups. Monocyte counts were statistically decreased in the mild/moderate group compared with the control group. Neutrophil counts were significantly higher in the mild/moderate and severe groups than in the control group. Erythrocyte counts were increased in the mild/moderate and severe groups compared with the control group. Vitamin D concentrations were statistically lower in the mild/moderate and severe groups than in the control group. However, no statistical differences in Vitamin D concentrations were observed between the mild/moderate and severe groups. There was a negative and significant correlation between erythrocyte counts and vitamin D concentrations (r = -0.64, P < .0001). While erythrocyte counts increased in the severe group compared with the mild/moderate group, vitamin D concentrations decreased. Also, a negative and significant correlation was observed between platelet counts and vitamin D concentrations (r = -0.74, P < .0001).

CONCLUSIONS

The results of this study determined that serum vitamin D concentrations in calves with pneumonia were lower than those in healthy calves. Detailed studies on the etiologic and prognostic importance of low vitamin D levels in calves with enzootic pneumonia may provide valuable data for prevention and treatment.

Association of air pollution and weather conditions during infection course with COVID-19 case fatality rate in the United Kingdom

Although the relationship between the environmental factors, such as weather conditions and air pollution, and COVID-19 case fatality rate (CFR) has been found, the impacts of these factors to which infected cases are exposed at different infectious stages (e.g., virus exposure time, incubation period, and at or after symptom onset) are still unknown. Understanding this link can help reduce mortality rates. During the first wave of COVID-19 in the United Kingdom (UK), the CFR varied widely between and among the four countries of the UK, allowing such differential impacts to be assessed. We developed a generalized linear mixed-effect model combined with distributed lag nonlinear models to estimate the odds ratio of the weather factors (i.e., temperature, sunlight, relative humidity, and rainfall) and air pollution (i.e., ozone, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]) using data between March 26, 2020 and September 15, 2020 in the UK. After retrospectively time adjusted CFR was estimated using back-projection technique, the stepwise model selection method was used to choose the best model based on Akaike information criteria and the closeness between the predicted and observed values of CFR. The risk of death reached its maximum level when the low temperature (6 °C) occurred 1 day before (OR 1.59; 95% CI 1.52-1.63), prolonged sunlight duration (11-14 h) 3 days after (OR 1.24; 95% CI 1.18-1.30) and increased [Formula: see text] (19 μg/m3) 1 day after the onset of symptom (OR 1.12; 95% CI 1.09-1.16). After reopening, many COVID-19 cases will be identified after their symptoms appear. The findings highlight the importance of designing different preventive measures against severe illness or death considering the time before and after symptom onset.

Bosentan and Pulmonary Hypertension Caused by COVID-19: A Pilot Randomized Double-blind Clinical Study

INTRODUCTION/OBJECTIVE

Coronavirus disease 2019 (COVID-19) has been the biggest pandemic in history, with severe complications, such as acute respiratory distress syndrome and pulmonary hypertension (PH). An endothelin-1 (ET-1) receptor antagonist, such as bosentan, may be beneficial in treating elevated ET-1 levels. Hence, our study aimed to evaluate the therapeutic effects of bosentan in patients with COVID-19-induced PH.

METHODS

A single-centre, randomized, double-blind study involving 72 participants was carried out; 36 received bosentan and the other 36 received a placebo. Pulmonary arterial pressure, tricuspid valve pressure gradient, and right atrial pressure were measured using echocardiography. The Cox proportional hazards regression model was used to investigate the impact of bosentan and patients' age on mortality during a 6-month follow-up period.

RESULTS

In-hospital mortality was significantly lower in the case group (13%) compared with the control group (33.3%) (P=0.003). Additionally, bosentan improved echocardiographic parameters, such as systolic pulmonary artery pressure and tricuspid regurgitation gradient (P=0.011 and P=0.003, respectively). Bosentan use was a significant predictor of long-term mortality rates for 600 days [age-adjusted hazard ratio of 5.24 (95% CI 1.34 to 20.46)].

CONCLUSION

This study provided a mixed perspective on the use of bosentan therapy in patients with COVID-19-related PH. Bosentan effectively reduced in-hospital mortality and improved echocardiographic measures. However, the treatment group showed an increased requirement for supplemental oxygen therapy and long-term mortality. Further studies with larger sample sizes are necessary to elucidate the effects of bosentan in PH following COVID-19.

Vitamin D levels in Portuguese military personnel

INTRODUCTION

In Portugal, most adults have inadequate levels of vitamin D. Active duty military personnel need to be always ready for duty, perform tasks in specific contexts and overcome high physical and mental demands, which raises the relevance of knowing their vitamin D levels. This study aims to characterise vitamin D levels of Portuguese active duty military personnel and evaluate the effect of military status on the prevalence of vitamin D sufficiency, adjusted for season of the year, age and gender.

METHODS

A retrospective cross-sectional study, based on vitamin D measurements carried out at the Armed Forces Hospital between 2014 and 2020, was fulfilled including the variables age, gender, vitamin D level and dosing date for military personnel and civilians. Comparison of proportions test and the generalised linear regression model were used for data analysis with a significance level of 5%.

RESULTS

Out of 2782 subjects, 62.7% were military personnel. Mean±SD level of vitamin D was 24.5±10.6 ng/mL and 23.7±11.5 ng/mL in military personnel and civilians, respectively. In the military personnel, the prevalence of vitamin D sufficiency, insufficiency and deficiency was, respectively, 25.2%, 40.1% and 34.6%. Prevalence of vitamin D sufficiency was similar in the civilians cohort and, also, between Armed Forces branches. Military status had no effect on the prevalence of vitamin D sufficiency, especially after adjustments.

CONCLUSIONS

We present data on vitamin D levels of Portuguese active duty military personnel. Our results found that military personnel are no more at risk of vitamin D inadequacy than civilians, but only a quarter of active duty military personnel had vitamin D sufficiency. Therefore, they can benefit from vitamin D levels assessment towards vitamin D levels optimisation. Further studies are still needed, especially among military personnel with higher risk of vitamin D deficiency.

Dietary supplements to reduce symptom severity and duration in people with SARS-CoV-2: a double-blind randomised controlled trial

BACKGROUND

COVID-19 has caused morbidity, hospitalisation and mortality worldwide. Despite effective vaccines, there is still a need for effective treatments, especially for people in the community. Dietary supplements have long been used to treat respiratory infections, and preliminary evidence indicates some may be effective in people with COVID-19. We sought to evaluate whether a combination of vitamin C, vitamin D3, vitamin K2 and zinc could improve overall health and decrease symptom burden in outpatients diagnosed with COVID-19.

METHODS

Participants were randomised to receive either vitamin C (6 g), vitamin D3 (1000 units), vitamin K2 (240 μg) and zinc acetate (75 mg) or placebo daily for 21 days and were followed for 12 weeks. An additional loading dose of 50 000 units vitamin D3 (or placebo) was given on day one. The primary outcome was participant-reported overall health using the EuroQol Visual Assessment Scale summed over 21 days. Secondary outcomes included health status, symptom severity, symptom duration, delayed return to usual health, frequency of hospitalisation and mortality.

RESULTS

90 patients (46 control, 44 treatment) were randomised. The study was stopped prematurely due to insufficient capacity for recruitment. The mean difference (control-treatment) in cumulative overall health was -37.4 (95% CI -157.2 to 82.3), p=0.53 on a scale of 0-2100. No clinically or statistically significant differences were seen in any secondary outcomes.

INTERPRETATION

In this double-blind, placebo-controlled, randomised trial of outpatients diagnosed with COVID-19, the dietary supplements vitamin C, vitamin D3, vitamin K2 and zinc acetate showed no clinically or statistically significant effects on the documented measures of health compared with a placebo when given for 21 days. Termination due to feasibility limited our ability to demonstrate the efficacy of these supplements for COVID-19. Further research is needed to determine clinical utility.

TRIAL REGISTRATION NUMBER

NCT04780061.

Vitamin D Influences the Activity of Mast Cells in Allergic Manifestations and Potentiates Their Effector Functions against Pathogens

Mast cells (MCs) are abundant at sites exposed to the external environment and pathogens. Local activation of these cells, either directly via pathogen recognition or indirectly via interaction with other activated immune cells and results in the release of pre-stored mediators in MC granules. The release of these pre-stored mediators helps to enhance pathogen clearance. While MCs are well known for their protective role against parasites, there is also significant evidence in the literature demonstrating their ability to respond to viral, bacterial, and fungal infections. Vitamin D is a fat-soluble vitamin and hormone that plays a vital role in regulating calcium and phosphorus metabolism to maintain skeletal homeostasis. Emerging evidence suggests that vitamin D also has immunomodulatory properties on both the innate and adaptive immune systems, making it a critical regulator of immune homeostasis. Vitamin D binds to its receptor, called the vitamin D receptor (VDR), which is present in almost all immune system cells. The literature suggests that a vitamin D deficiency can activate MCs, and vitamin D is necessary for MC stabilization. This manuscript explores the potential of vitamin D to regulate MC activity and combat pathogens, with a focus on its ability to fight viruses.

Association of serum vitamin D concentration with the final course of hospitalization in patients with COVID-19

Background

Vitamin D deficiency is a substantial public health problem. The present study evaluated the association between vitamin D concentration and hospitalization and mortality risk in patients with coronavirus disease 19 (COVID-19).

Methods

This study used the COronavirus in LOwer Silesia (COLOS) dataset collected between February 2020 and June 2021. The medical records of 474 patients with confirmed severe acute respiratory syndrome 2 (SARS-CoV-2) infection, and whose vitamin D concentration was measured, were analyzed.

Results

We determined a significant difference in vitamin D concentration between discharged patients and those who died during hospitalization (p = 0.0096). We also found an effect of vitamin D concentration on the risk of death in patients hospitalized due to COVID-19. As vitamin D concentration increased, the odds ratio (OR) for death slightly decreased (OR = 0.978; 95% confidence interval [CI] = 0.540-0.669). The vitamin D concentration cutoff point was 15.40 ng/ml. In addition, patients with COVID-19 and serum 25-hydroxyvitamin D (25(OH)D) concentrations < 30 ng/ml had a lower survival rate than those with serum 25(OH)D ≥ 30 ng/ml (log-rank test p = 0.0018). Moreover, a Cox regression model showed that patients with an estimated glomerular filtration rate (eGFR) ≥ 60 ml/min/1.73 m2 and higher vitamin D concentrations had a 2.8% reduced risk of mortality (hazard ratio HR = 0.972; CI = 0.95-0,99; p = 0.0097).

Conclusions

The results indicate an association between 25(OH)D levels in patients with COVID-19 and the final course of hospitalization and risk of death.

Effects of Vitamin D Supplementation and Degradation on the Innate Immune System Response: Insights on SARS-CoV-2

Vitamin D has been proven to be a strong stimulator of mechanisms associated with the elimination of pathogens. Because of its recognized effectiveness against viral infections, during SARS-CoV-2 infection, the effects of Vitamin D supplementation have been the object of debate. This study aims to contribute to this debate by the means of a qualitative phenomenological mathematical model in which the role of Vitamin D and its interactions with the innate immune system are explicitly considered. We show that Vitamin D influx and degradation can be considered as possible control parameters for the disease evaluation and recovery. By varying Vitamin D influx, three dynamical scenarios have been found with different modalities of recovery from the disease. Inside each scenario, Vitamin D degradation has been related to different degrees of severity in disease development. Interestingly, the emergence of hysteretic phenomenologies when Vitamin D influx is too low can be related to the onset of Long-COVID syndrome, confirming clinical evidence from recent studies on the topic.

Vitamin D Deficiency in COVID-19 Patients and Role of Calcifediol Supplementation

Hypovitaminosis D has been associated with worse outcome in respiratory tract infections, with conflicting opinions regarding its role in Coronavirus-19 disease (COVID-19). Our study aimed to evaluate the possible relationship between 25-OH vitamin D (25OHD) values and the following conditions in patients hospitalized for COVID-19: prognosis, mortality, invasive (IV) and non-invasive (NIV) mechanical ventilation, and orotracheal intubation (OTI). A further objective was the analysis of a possible positive effect of supplementation with calcifediol on COVID-19 severity and prognosis. We analyzed 288 patients hospitalized at the San Giovanni di Dio Hospital in Florence and the Santa Maria alle Scotte Hospital in Siena, from November 2020 to February 2021. The 25OHD levels correlated positively with the partial pressure of oxygen and FiO2 (PaO2/FiO2) ratio (r = 0.17; p < 0.05). Furthermore, when we analyzed the patients according to the type of respiratory support, we found that 25OHD levels were markedly reduced in patients who underwent non-invasive ventilation and orotracheal intubation (OTI). The evaluation of the length of hospitalization in our population evidenced a longer duration of hospitalization in patients with severe 25OHD deficiency (<10 ng/mL). Moreover, we found a statistically significant difference in the mortality rate between patients who had 25OHD levels below 10 ng/mL and those with levels above this threshold in the total population (50.8% vs. 25.5%, p = 0.005), as well as between patients with 25OHD levels below 20 ng/mL and those with levels above that threshold (38.4% vs. 24.6%, p = 0.04). Moreover, COVID-19 patients supplemented with calcifediol presented a significantly reduced length of hospitalization (p < 0.05). Interestingly, when we analyzed the possible effects of calcifediol on mortality rate in patients with COVID-19, we found that the percentage of deaths was significantly higher in patients who did not receive any supplementation than in those who were treated with calcifediol (p < 0.05) In conclusion, we have demonstrated with our study the best prognosis of COVID-19 patients with adequate vitamin D levels and patients treated with calcifediol supplementation.

Vitamin D in pediatric age: Current evidence, recommendations, and misunderstandings

In recent years vitamin D has been in the spotlight of many researchers for its possible role in various disorders, including autoimmune and infectious diseases. Even if vitamin D deficiency remains a major public health problem, its symptomatic manifestations are less and less common in clinical practice, and pediatric age represents a “gray area” where vitamin D supplementation is often administered in the absence of an effective evaluation of its status. Moreover, a poor knowledge about different definitions of “deficiency,” “insufficiency,” and similar terms is spread among clinicians, while guidelines are not univocal, especially after the first year of life. The aim of this brief opinion paper is to sum up recent evidence about vitamin D status and its supplementation in pediatrics, in order to better clarify a common definition of its deficiency. The aim of this opinion article is to raise awareness on this topic among clinicians and encourage a discussion on the real need for routine 25-hydroxycholecalciferol serum evaluation and its supplementation.

A Prospective Analysis of Vitamin D Levels in Pregnant Women Diagnosed with Gestational Hypertension after SARS-CoV-2 Infection

The great majority of existing studies suggests that the prognosis and outcomes of SARS-CoV-2 infections are improved with adequate vitamin D levels, with or without supplementation. Simultaneously, whether vitamin D supplementation during pregnancy lessens the chance of developing gestational hypertension is controversial. The objective of the present research was to evaluate whether vitamin D levels during pregnancy differ substantially among pregnant women who develop gestational hypertension following SARS-CoV-2 infection. The current research was designed as a prospective cohort following the pregnant women admitted to our clinic with COVID-19 until 36 weeks of gestation. Total vitamin D (25(OH)D) levels were measured in the three study groups in which pregnant women with COVID-19 during pregnancy and a diagnosis of hypertension after 20 weeks of gestation were considered the group of cases (GH-CoV). The second group (CoV) included those with COVID-19 and no hypertension, while the third group (GH) included those with hypertension and no COVID-19. It was observed that 64.4% of SARS-CoV-2 infections in the group of cases occurred during the first trimester, compared to 29.2% in the first trimester among the controls who did not develop GH. Normal vitamin D levels were measured at admission in a significantly higher proportion of pregnant women without GH (68.8% in the CoV group vs. 47.9% in the GH-CoV group and 45.8% in the GH group). At 36 weeks of gestation, the median values of 25(OH)D in the CoV group was 34.4 (26.9-39.7) ng/mL compared to 27.9 (16.2-32.4) ng/mL in the GH-CoV group and 29.5 ng/mL (18.4-33.2) in the GH group, while the blood pressure measurements remained over 140 mmHg among the groups who developed GH. There was a statistically significant negative association between serum 25(OH)D levels and systolic blood pressure (rho = -0.295; p-value = 0.031); however, the risk of developing GH was not significantly higher among pregnant women with COVID-19 if the vitamin D levels were insufficient (OR = 1.19; p-value = 0.092) or deficient (OR = 1.26; p-value = 0.057). Although insufficient or deficient vitamin D among pregnant women with COVID-19 was not an independent risk factor for the development of GH, it is likely that an association between first-trimester SARS-CoV-2 infection and low vitamin D plays a key role in developing gestational hypertension.

An overview on role of nutrition on COVID-19 immunity: Accumulative review from available studies

The novel coronavirus infection (COVID-19) conveys a serious global threat to health and economy. A common predisposing factor for development to serious progressive disease is presence of a low-grade inflammation, e.g., as seen in diabetes, metabolic syndrome, and heart failure. Micronutrient deficiencies may also contribute to the development of this state. Therefore, the aim of the present study is to explore the role of the nutrition to relieve progression of COVID-19. According PRISMA protocol, we conducted an online databases search including Scopus, PubMed, Google Scholar and web of science for published literatures in the era of COVID-19 Outbreak regarding to the status of nutrition and COVID-19 until December 2021. There were available studies (80 studies) providing direct evidence regarding the associations between the status of nutrition and COVID-19 infection. Adequate nutritional supply is essential for resistance against other viral infections and also for improvement of immune function and reduction of inflammation. Hence, it is suggested that nutritional intervention which secures an adequate status might protect against the novel coronavirus SARS-CoV-2 (Severe Acute Respiratory Syndrome - coronavirus-2) and mitigate its course. We also recommend initiation of adequate nutritional supplementation in high-risk areas and/or soon after the time of suspected infection with SARS-CoV-2. Subjects in high-risk groups should have high priority for applying this nutritive adjuvant therapy that should be started prior to administration of specific and supportive medical measures.

Sleep Disturbance and Immunological Consequences of COVID-19

The overarching importance of sleep was further emphasized during the pandemic of COVID-19. The subjects infected by COVID-19 frequently experience sleep disturbances; some are long-lasting problems and decrease the quality of life. Insomnia is the most studied sleep disorder associated with COVID-19. Insomnia affects patients who have experienced an infection and the general population. Good sleep is important in maintaining mental and physical health, including immune system functions. The interconnections between insomnia, the immune system, and COVID-19 are complex. Insomnia triggers numerous immune system dysregulations and makes individuals more vulnerable to respiratory infections. This narrative review overviews the influence of the COVID-19 pandemic on the immune system through sleep disorders.

Influence of the COVID-19 pandemic on the vitamin D status of children: A cross-sectional study

Coronavirus disease 2019 (COVID-19), as well as its prevention and control measures, seriously affected people's livehood, which may have affected the body's level of vitamin D (VD). This study aimed to investigate the effect of the COVID-19 pandemic on the VD status of children in Zhengzhou, China. In this study, we included 12 272 children in 2019 (before the COVID-19 pandemic) and 16 495 children in 2020 (during the COVID-19 pandemic) to examine the changes in VD levels and deficiency rates among children before and during the COVID-19 pandemic. Total VD levels in 2020 were significantly higher than those in 2019 (26.56 [18.15, 41.40] vs. 25.98 [17.92, 40.09] ng/ml, p  < 0.001). Further analysis revealed that during the COVID-19 pandemic control period in 2020, the VD levels in February, March, and April were lower than those in the same months of 2019, while the VD deficiency rates were significantly higher. Additionally, our data revealed that VD levels decreased significantly with age. Among children older than 6 years, the VD deficiency rate exceeded 50%. These results indicate that we should pay close attention to VD supplementation during the COVID-19 pandemic control period and in children older than 6 years of age.

Vitamin D Deficiency in Both Oral and Systemic Manifestations in SARS-CoV-2 Infection: Updated Review

The specialized literature emphasizes the fact that vitamin D has a potentially beneficial effect in the context of the current COVID-19 pandemic. The purpose of this article is to highlight the role of vitamin D, both prophylactic and curative, in the treatment of patients diagnosed with COVID-19. Even though its relevance is still unknown and causes various controversies, there is currently no specific treatment for patients diagnosed with COVID-19. There are various prevention strategies with new vaccination schedules, but additional randomized and clinical trials are still needed to combat this pandemic. In addition to the systemic manifestations of SARS-CoV-2 infection, oral manifestations of this disease have also been described in the literature. The etiology of oral manifestations associated with COVID-19 infection and vitamin D deficiency remains controversial. In the present studies, oral manifestations such as salivary gland infections, aphthae, erythema, gingivitis, ulcers, etc. have been reported. This is a new topic, and the prevalence of manifestations is described in only a few studies, which is inconsistent with the number of COVID-19 cases reported since the beginning of the pandemic. The clinical symptomatology in patients with current COVID-19 infection is polymorphic. Whether the oral manifestation is directly caused by SARS-CoV-2 or a secondary manifestation remains an important topic to analyze and discuss.

Association between Vitamin D Status and Secondary Infections in Patients with Severe COVID-19 Admitted in the Intensive Care Unit of a Tertiary-Level Hospital in Turkey

There are several studies showing that the vitamin D status can determine risk of COVID-19 infections, severity and mortality from coronavirus disease 2019 (COVID-19). However, the association between vitamin D (25(OH)D) and secondary infections in the prognosis of COVID-19 patients has not been reported yet. The aim was to investigate whether the vitamin D status affects the rates of secondary infections in patients with severe COVID-19 hospitalized in the intensive care unit (ICU) of a tertiary-level hospital in Turkey. The data of 194 patients with diagnosis of severe COVID-19 who were admitted to the ICU from March 2020 to June 2021 and older than 18 years were evaluated in this retrospective study. The patients were divided into two groups according to total serum 25(OH)D level as normal group (≥20 ng/mL) and low group (<20 ng/mL). The 25(OH)D level was low in 118 (60.8%) and normal in 76 (39.2%) patients. The mean age of the low group was significantly higher than that of the normal group (67.02 ± 14.47 vs. 61.70 ± 14.38; p = 0.013). The systolic and diastolic blood pressure as well as the Glasgow coma scale score of the low group were significantly lower than that of the normal group (p = 0.004, 0.002 and 0.001, respectively). The intubation rate and APACHE (Acute Physiology and Chronic Health Evaluation) score of the low group was significantly higher than that of the normal group (p = 0.001). The platelets number and blood pH decreased, and the neutrophil/lymphocyte ratio, procalcitonin, lactate, urea, creatinine and lactate dehydrogenase concentrations increased significantly in the low group (p < 0.05). The mortality rate was 79.7% in the low group and 22.4% in the normal group (p < 0.001). Microbiological growth was observed in 68.6% of the normal group and 52.6% of the normal group (p = 0.025). The number of cultures with resistant bacteria was significantly higher in the low group (25.9%) than that in the normal group (17.5%) (p = 0.035). The severe COVID-19 patients hospitalized with vitamin D deficiency may have increased risks of poor prognosis and mortality due to secondary infections in the ICU.

Serum vitamin D levels and COVID-19 during pregnancy: A systematic review and meta-analysis

Background

Serum vitamin D levels are reported to be associated with the risk of incidence and severity of COVID-19 in the general population. During pregnancy, immune system alterations in line with changes in vitamin D metabolism may affect the course of COVID-19. Thus, we aimed to systematically review the association between vitamin D, pregnancy, and COVID-19.

Methods

A systematic literature search was conducted in PubMed, Scopus, Web of Science, Embase, and Google Scholar until the end of May 2022. Mean differences (MD) with 95% CI were used as desired effect sizes to assess the association of serum vitamin D levels with the risk of incidence and severity of COVID-19 in pregnant women.

Results

Among 259 records, 7 and 6 studies were included in the systematic review and meta-analysis, respectively. All included studies had acceptable quality. Our results demonstrated an insignificant difference between infected women and non-infected controls (MD = -2.55 ng/ml, 95% CI: −6.85 – 1.74). But serum vitamin D levels in severe/moderate cases compared to mild ones (MD = −2.71 ng/ml, 95% CI: −4.18 to −1.24) are significantly lower.

Conclusion

Based on the current evidence, serum vitamin D level does not associate with the risk of SARS-CoV-2 infection among pregnant women, but we find a significant association with the severity of the disease. These findings may be helpful in similar conditions and future studies to better understand the complex immune alterations during pregnancy.

Immunoceuticals: Harnessing Their Immunomodulatory Potential to Promote Health and Wellness

Knowledge that certain nutraceuticals can modulate the immune system is not new. These naturally occurring compounds are known as immunoceuticals, which is a novel term that refers to products and systems that naturally improve an individual's immuno-competence. Examples of immunoceuticals include vitamin D3, mushroom glycans, flavonols, quercetin, omega-3 fatty acids, carotenoids, and micronutrients (e.g., zinc and selenium), to name a few. The immune system is a complex and highly intricate system comprising molecules, cells, tissues, and organs that are regulated by many different genetic and environmental factors. There are instances, such as pathological conditions, in which a normal immune response is suboptimal or inappropriate and thus augmentation or tuning of the immune response by immunoceuticals may be desired. With infectious diseases, cancers, autoimmune disorders, inflammatory conditions, and allergies on the rise in both humans and animals, the importance of the use of immunoceuticals to prevent, treat, or augment the treatment of these conditions is becoming more evident as a natural and often economical approach to support wellness. The global nutraceuticals market, which includes immunoceuticals, is a multi-billion-dollar industry, with a market size value of USD 454.55 billion in 2021, which is expected to reach USD 991.09 billion by 2030. This review will provide an overview of the immune system, the importance of immunomodulation, and defining and testing for immunocompetence, followed by a discussion of several key immunoceuticals with clinically proven and evidence-based immunomodulatory properties.

Nutrition Guidelines for Improved Clinical Care

Given the importance of poor nutrition as a cause for human chronic disease, it is surprising that nutrition receives so little attention during medical school training and in clinical practice. Specific vitamins, minerals, fatty acids, amino acids and water in the diet are essential for health, and deficiencies lead or contribute to many diseases. Proper use of the dietary guidelines and nutrition facts labeling can improve nutritional status and lead to the consumption of a healthy diet. COVID-19 has altered access to nutritious foods for millions and increased awareness of the importance of diet and immune function. An improved appreciation for nutrition will improve the outcomes of clinical care.

Analysis of the Nutritional Value of the Diets Presented in Women's and Sports Magazines before and during the COVID-19 Pandemic

For consumers, among the most important sources of information related to nutrition are popular journals and magazines, including women’s and sports, but the diets presented there may lead to unhealthy weight-control behaviors. The aim of the study was to assess the nutritional value of regular and low-calorie diets presented in Polish women’s and sports magazines before and during COVID-19 pandemic. The study was based on two popular Polish magazines—one women’s magazine and one sports magazine, which regularly present various types of diets. The nutritional value of all the diets published from January 2014 to May 2022 was analyzed. The total number of included single-day menus was n = 119, while for analysis they were stratified based on: type of magazine (published in the women’s magazine n = 41 and in the sports magazine n = 78), year of publication (before the COVID-19 pandemic n = 78 and during n = 41), and type of diet (regular n = 61 and low-calorie n = 58). The analysis included the energy value and nutritional value. For the type of magazine, the diets published in the sports magazine were characterized by a higher intake of fat (p < 0.0001 for intake in grams and in % of energy) and calcium (p = 0.0330), whereas the diets published in the women’s magazine were characterized by a higher intake of carbohydrates (p = 0.0226 for intake in grams, and p = 0.0002 for intake in % of energy) and fiber (p = 0.0163). For the year of publication, the diets published during the COVID-19 pandemic were characterized by a higher intake of protein (p = 0.0166 for intake in grams), sodium (p = 0.0465), calcium (p < 0.0001), vitamin D (p = 0.0197), vitamin B6 (p = 0.0207), and vitamin B12 (p = 0.0277), whereas the diets published before the COVID-19 pandemic were characterized by a higher intake of carbohydrates (p = 0.0243 for intake in % of energy). For the type of diet, the regular diets were characterized by a higher energy value (p = 0.0020), as well as by a higher intake of fat (p = 0.0162 for intake in grams), carbohydrates (p = 0.0390 for intake in grams), mono- and oligosaccharides (p = 0.0084 for intake in % of energy), fiber (p < 0.0001), magnesium (p = 0.0323), iron (p = 0.0307), and vitamin B6 (p = 0.0204). The nutritional value of the diets presented in the Polish women’s and sports magazines was not justified by the type of magazine or type of diet, associated with the target group, which may cause the following of improperly balanced diets. However, the changes in the typical nutritional value of diets presented in the Polish women’s and sports magazines during the COVID-19 pandemic were justified by some specific needs for the prevention and treatment of COVID-19.

Prognostic Value of Catestatin in Severe COVID-19: An ICU-Based Study

Catestatin is a pleiotropic peptide with a wide range of immunomodulatory effects. Considering that patients with a severe COVID-19 infection have a major immunological dysregulation, the aim of this study was to evaluate catestatin levels in patients with COVID-19 treated in the intensive care unit (ICU) and to compare them between the fatal and non-fatal outcomes. The study included 152 patients with severe COVID-19, out of which 105 had a non-fatal outcome and 47 had a fatal outcome. Serum catestatin levels were estimated by an enzyme-linked immunosorbent assay in a commercially available diagnostic kit. The results show that catestatin levels were significantly lower in the fatal group compared to the non-fatal group (16.6 ± 7.8 vs. 23.2 ± 9.2 ng/mL; p < 0.001). Furthermore, there was a significant positive correlation between serum catestatin levels and vitamin D levels (r = 0.338; p < 0.001) while there was also a significant positive correlation between serum catestatin levels and growth differentiation factor-15 (GDF-15) levels (r = −0.345; p < 0.001). Furthermore, multivariate logistic regression showed that catestatin, GDF-15 and leukocyte count were significant predictors for COVID-19 survival. These findings imply that catestatin could be playing a major immunomodulatory role in the complex pathophysiology of the COVID-19 infection and that serum catestatin could also be a predictor of a poor COVID-19 outcome.

Vitamin D and SARS-CoV2 infection, severity and mortality: A systematic review and meta-analysis

To assess the evidence on SARS-CoV2 infection and Covid-19 in relation to deficiency and supplementation of vitamin D, we conducted a systematic review up to April 2021. We summarised data from 38 eligible studies, which presented risk estimates for at least one endpoint, including two RCT and 27 cohort-studies: 205565 patients with information on 25OHD status and 2022 taking vitamin D supplementation with a total of 1197 admitted to the ICU or who needed invasive mechanical ventilation or intubation and hospital stay, and more than 910 Covid-19 deaths. Primary outcomes were severity and mortality and the main aim was to evaluate the association with vitamin D supplementation. Random effects models showed that supplementation was associated with a significant lower risk of both Covid-19 severe disease (SRR 0.38, 95% CI 0.20-0.72, 6 studies) and mortality (SRR 0.35, 95% CI 0.17-0.70, 8 studies). There were no statistically significant dose differences between studies: summary estimates with regular doses remain statistically significant, suggesting that higher doses are not necessary. For patients on vitamin D supplementation, a greater reduction in mortality risk emerged in older individuals and at higher latitudes. Regarding the quality of studies, assessed using the New Castle-Ottawa quality scale, the analysis revealed in most cases no statistically significant differences between low, medium or high quality studies. We found significant associations of vitamin D supplementation with Covid-19, encompassing risks of disease worsening and mortality, especially in seasons characterized by 25OHD deficiency and with not severe patients. Dedicated randomized clinical studies are encouraged to confirm these results.

Standard of care for COVID-19 in randomized clinical trials registered in trial registries and published in preprint servers and scholarly journals: a cross-sectional study

BACKGROUND

The concept of standard of care (SoC) treatment is commonly utilized in clinical trials. However, in a setting of an emergent disease, such as COVID-19, where there is no established effective treatment, it is unclear what the investigators considered as the SoC in early clinical trials. The aim of this study was to analyze and classify SoC reported in randomized controlled trial (RCT) registrations and RCTs published in scholarly journals and on preprint servers about treatment interventions for COVID-19.

METHODS

We conducted a cross-sectional study. We included RCTs registered in a trial registry, and/or published in a scholarly journal, and/or published on preprint servers medRxiv and bioRxiv (any phase; any recruitment status; any language) that aim to compare treatment interventions related to COVID-19 and SoC, available from January 1, 2020, to October 8, 2020. Studies using "standard" treatment were eligible for inclusion if they reported they used standard, usual, conventional, or routine treatment. When we found such multiple reports of an RCT, we treated those multiple sources as one unit of analysis.

RESULTS

Among 737 unique trials included in the analysis, 152 (21%) reported that SoC was proposed by the institutional or national authority. There were 129 (18%) trials that reported component(s) of SoC; the remaining trials simply reported that they used SoC, with no further detail. Among those 129 trials, the number of components of SoC ranged from 1 to 10. The most commonly used groups of interventions in the SoC were antiparasitics (62% of the trials), antivirals (57%), antibiotics (31%), oxygen (17%), antithrombotics/anticoagulants (14%), vitamins (13%), immunomodulatory agents (13%), corticosteroids (12%), analgesics/antipyretics (12%). Various combinations of those interventions were used in the SoC, with up to 7 different types of interventions combined. Posology, timing, and method of administration were frequently not reported for SoC components.

CONCLUSION

Most RCTs (82%) about treatment for COVID-19 that were registered or published in the first 9 months of the pandemic did not describe the "standard of care" they used. Many of those interventions have, by now, been shown as ineffective or even detrimental.

Vitamin D deficiency predicts 30-day hospital mortality of adults with COVID-19

Background & aims

Several studies have shown conflicting results for the relationship between vitamin D deficiency and COVID-19 outcomes. Here, we aimed to evaluate whether plasma 25(OH)D levels predict mortality in adults admitted with COVID-19, considering potential confounders.

Methods

We conducted a retrospective cohort study that included 115 adults (age 62.1 ± 17.6 years, 65 males) admitted to a Brazilian public hospital for severely symptomatic COVID-19. Subjects were classified into two groups according to their plasma levels of 25(OH)D: sufficiency (≥50 nmol/L) and the deficiency (<50 nmol/L). The diagnosis of COVID-19 was performed using real-time polymerase chain reaction (qPCR). In addition, direct competitive chemiluminescence immunoassay assessed serum 25(OH)D levels.

Results

The all-cause 30-day mortality was 13.8% (95% CI: 6.5%–21%) in the group of patients with sufficient plasma 25(OH)D levels and 32.1% (95% CI: 14.8%–49.4%) among those with deficient plasma 25(OH)D levels. Cox regression showed that plasma 25(OH)D levels remained a significant predictor of mortality even after adjusting for the covariates sex, age, length of the delay between symptom onset and hospitalization, and disease severity (HR = 0.98, 95% CI: 0.96–1.00; p = 0.02).

Conclusion

Vitamin D deficiency predicts higher mortality risk in adults with COVID-19.

High-dose vitamin D versus placebo to prevent complications in COVID-19 patients: Multicentre randomized controlled clinical trial

Background

The role of oral vitamin D₃ supplementation for hospitalized patients with COVID-19 remains to be determined. The study was aimed to evaluate whether vitamin D₃ supplementation could prevent respiratory worsening among hospitalized patients with COVID-19.

Methods and findings

We designed a multicentre, randomized, double-blind, sequential, placebo-controlled clinical trial. The study was conducted in 17 second and third level hospitals, located in four provinces of Argentina, from 14 August 2020 to 22 June 2021. We enrolled 218 adult patients, hospitalized in general wards with SARS-CoV-2 confirmed infection, mild-to-moderate COVID-19 and risk factors for disease progression. Participants were randomized to a single oral dose of 500 000 IU of vitamin D₃ or matching placebo. Randomization ratio was 1:1, with permuted blocks and stratified for study site, diabetes and age (≤60 vs >60 years). The primary outcome was the change in the respiratory Sepsis related Organ Failure Assessment score between baseline and the highest value recorded up to day 7. Secondary outcomes included the length of hospital stay; intensive care unit admission; and in-hospital mortality. Overall, 115 participants were assigned to vitamin D₃ and 105 to placebo (mean [SD] age, 59.1 [10.7] years; 103 [47.2%] women). There were no significant differences in the primary outcome between groups (median [IQR] 0.0 [0.0–1.0] vs 0.0 [0.0–1.0], for vitamin D₃ and placebo, respectively; p = 0.925). Median [IQR] length of hospital stay was not significantly different between vitamin D₃ group (6.0 [4.0–9.0] days) and placebo group (6.0 [4.0–10.0] days; p = 0.632). There were no significant differences for intensive care unit admissions (7.8% vs 10.7%; RR 0.73; 95% CI 0.32 to 1.70; p = 0.622), or in-hospital mortality (4.3% vs 1.9%; RR 2.24; 95% CI 0.44 to 11.29; p = 0.451). There were no significant differences in serious adverse events (vitamin D₃ = 14.8%, placebo = 11.7%).

Conclusions

Among hospitalized patients with mild-to-moderate COVID-19 and risk factors, a single high oral dose of vitamin D₃ as compared with placebo, did not prevent the respiratory worsening.

Trial registration

ClincicalTrials.gov Identifier: NCT04411446.

Relationship of anti-SARS-CoV-2 IgG antibodies with Vitamin D and inflammatory markers in COVID-19 patients

Several studies have found an association of COVID-19 disease severity with Vitamin D deficiency and higher levels of anti-SARS-CoV-2 IgGs. The aim of this study was to determine whether levels of Vitamin D and "inflammatory state" influence the magnitude of anti-SARS-CoV-2 IgGs levels in COVID-19 patients. For this purpose, in 67 patients levels of anti-SARS-CoV-2 IgG were measured in week 4 whereas in 52 patients levels of Vitamin D were measured in week 1 after symptom onset. We found that low Vitamin D levels were significantly associated with age and disease severity whereas there was a trend without significance, towards negative correlation of Vitamin D with anti-SARS-CoV-2 IgG. Anti-SARS-CoV-2 IgG were significantly higher in older ages, patients with severe disease, diabetes and those who received corticosteroid and antibiotic therapy. There was a positive correlation of anti-SARS-CoV-2 IgG with IL-6, CRP, LDH, ESR and with percentages of granulocytes. In conclusion, Vitamin D and anti-SARS-CoV-2 IgG share common parameters associated with inflammatory state. However, even though Vitamin D protects against severe forms of COVID-19 it could not directly affect anti-SARS-CoV-2 IgG production.

Clinical aspects of SARS-CoV-2 infection and vitamin D : COVID-19 and the endocrine system: special issue for reviews in endocrine and metabolic disorders (Felipe Casaneuva, Editor in Chief) A. Giustina and JP Bilezikian, Guest Editors

In December 2019, the first cases of severe acute respiratory syndrome due to a new coronavirus (SARS-Cov-2), later designated as Covid-19, were described in China. With rapid advance of the infection to several continents, in March 2020, WHO declared this to be a pandemic. In April 2020, the first papers suggesting a possible role of Vitamin D deficiency in the severity of this infection began to appear and dozens of articles evaluating a potential relationship of vitamin D with COVID have emerged subsequntly. This possibility was raised based on pre-existing evidence of the effects of Vitamin D on the immune system, and more specifically on acute respiratory viral infections. In addition, most Covid-19 victims belong to groups at risk for vitamin D deficiency such as the elderly, obese, chronically ill, and specific ethnic groups. Although with some contradictory reports exist, most observational and cohort studies find a relationship of low vitamin D status with greater Covid severity, others, including the few interventional studies available show inconsistent results. This paper aims to present the rapidly expanding literature to date regarding the clinical relevance of vitamin D in Covid-19 and, consequently, the reasonableness of avoiding its deficiency to keep the immune system able to respond in the best way to this acute viral infection. In the meantime, we wait for publication of several prospective randomized controlled studies that are underway, evaluating the effects of treatment with vitamin D or metabolites on the severity of Covid-19 outcomes.

Antioxidant, anti-inflammatory and immunomodulatory roles of vitamins in COVID-19 therapy

oxidative stress is caused by an abundant generation of reactive oxygen species, associated to a diminished capacity of the endogenous systems of the organism to counteract them. Activation of pro-oxidative pathways and boosting of inflammatory cytokines are always encountered in viral infections, including SARS-CoV-2. So, the importance of counteracting cytokine storm in COVID-19 pathology is highly important, to hamper the immunogenic damage of the endothelium and alveolar membranes. Antioxidants prevent oxidative processes, by impeding radical species generation. It has been proved that vitamin intake lowers oxidative stress markers, alleviates cytokine storm and has a potential role in reducing disease severity, by lowering pro-inflammatory cytokines, hampering hyperinflammation and organ failure. For the approached compounds, direct antiviral roles are also discussed in this review, as these activities encompass secretion of antiviral peptides, modulation of angiotensin-converting enzyme 2 receptor expression and interaction with spike protein, inactivation of furin protease, or inhibition of pathogen replication by nucleic acid impairment induction. Vitamin administration results in beneficial effects. Nevertheless, timing, dosage and mutual influences of these micronutrients should be carefullly regarded.

Association of vitamin D deficiency with COVID-19 severity and mortality in Iranian people: a prospective observational study

Background

As the coronavirus disease 2019 (COVID-19) pandemic continues to escalate, it is important to identify the prognostic factors related to increased mortality and disease severity. To assess the possible associations of vitamin D level with disease severity and survival, we studied 248 hospitalized COVID-19 patients in a single center in a prospective observational study from October 2020 to May 2021 in Tehran, Iran.

Methods

Patients who had a record of their 25-hydroxyvitamin D level measured in the previous year before testing positive with COVID-19 were included. Serum 25-hydroxyvitamin D level was measured upon admission in COVID-19 patients. The associations between clinical outcomes of patients and 25-hydroxyvitamin D level were assessed by adjusting for potential confounders and estimating a multivariate logistic regression model.

Results

The median (interquartile range) age of patients was 60 years (44–74 years), and 53% were male. The median serum 25-hydroxyvitamin D level prior to admission decreased with increasing COVID-19 severity (P=0.009). Similar findings were obtained when comparing median serum 25-hydroxyvitamin D on admission between moderate and severe patients (P=0.014). A univariate logistic regression model showed that vitamin D deficiency prior to COVID-19 was associated with a significant increase in the odds of mortality (odds ratio, 2.01; P=0.041). The multivariate Cox model showed that vitamin D deficiency on admission was associated with a significant increase in risk for mortality (hazard ratio, 2.35; P=0.019).

Conclusions:

Based on our results, it is likely that deficient vitamin D status is associated with increased mortality in COVID-19 patients. Thus, evaluating vitamin D level in COVID-19 patients is warranted.

An Overview of Systematic Reviews of the Role of Vitamin D on Inflammation in Patients with Diabetes and the Potentiality of Its Application on Diabetic Patients with COVID-19

Almost two years have passed since the outbreak reported for the first time in Wuhan of coronavirus disease 2019 (COVID-19), due to severe acute respiratory syndrome (SARS)-CoV-2 coronavirus, rapidly evolved into a pandemic. This infectious disease has stressed global health care systems. The mortality rate is higher, particularly in elderly population and in patients with comorbidities such as hypertension, diabetes mellitus, cardiovascular disease, chronic lung disease, chronic renal disease, and malignancy. Among them, subjects with diabetes have a high risk of developing severe form of COVID-19 and show increased mortality. How diabetes contributes to COVID-19 severity remains unclear. It has been hypothesized that it may be correlated with the effects of hyperglycemia on systemic inflammatory responses and immune system dysfunction. Vitamin D (VD) is a modulator of immune-response. Data from literature showed that vitamin D deficiency in COVID-19 patients increases COVID-19 severity, likely because of its negative impact on immune and inflammatory responses. Therefore, the use of vitamin D might play a role in some aspects of the infection, particularly the inflammatory state and the immune system function of patients. Moreover, a piece of evidence highlighted a link among vitamin D deficiency, obesity and diabetes, all factors associated with COVID-19 severity. Given this background, we performed an overview of the systematic reviews to assess the association between vitamin D supplementation and inflammatory markers in patients with diabetes; furthermore, vitamin D’s possible role in COVID-19 patients was assessed as well. Three databases, namely MEDLINE, PubMed Central and the Cochrane Library of Systematic Reviews, were reviewed to retrieve the pertinent data. The aim of this review is to provide insight into the recent advances about the molecular basis of the relationship between vitamin D, immune response, inflammation, diabetes and COVID-19.

Association of vitamin D deficiency with COVID-19 infection severity: Systematic review and meta-analysis

BACKGROUND

We sought to evaluate the association between vitamin D deficiency and the severity of coronavirus disease 2019 (COVID-19) infection.

METHODS

Multiple databases from 1 January 2019 to 3 December 2020 were searched for observational studies evaluating the association between vitamin D deficiency and severity of COVID-19 infection. Independent reviewers selected studies and extracted data for the review. The main outcomes of interest were mortality, hospital admission, length of hospital stay and intensive care unit admission.

RESULTS

Seventeen observational studies with 2756 patients were included in the analyses. Vitamin D deficiency was associated with significantly higher mortality (odds ratio [OR]: 2.47, 95% confidence interval [CI]: 1.50-4.05; 12 studies; hazard ratio [HR]: 4.11, 95% CI: 2.40-7.04; 3 studies), higher rates of hospital admissions (OR: 2.18, 95% CI: 1.48-3.21; 3 studies) and longer hospital stays (0.52 days; 95% CI: 0.25-0.80; 2 studies) as compared to nonvitamin D deficient status. Subgroup analyses based on different cut-offs for defining vitamin D deficiency, study geographic locations and latitude also showed similar trends.

CONCLUSIONS

Vitamin D deficiency is associated with greater severity of COVID-19 infection. Further studies are warranted to determine if vitamin D supplementation can decrease the severity of COVID-19.

Herbal Remedies, Nutraceuticals, and Dietary Supplements for COVID-19 Management: An Update

Currently, the world is facing a Coronavirus pandemic with a grave deficiency of specific therapy for Coronavirus Disease (COVID-19). Moreover, scientists attempt to discover the most refined approach to prevent this condition. Regarding COVID-19 infection, herbal medicines with immunomodulatory effects may offer patients a promising preventive treatment option. Several ayurvedic and Traditional Chinese Medicine (TCM) are effective during this worrisome Coronavirus pandemic i.e. Tinospora cordifolia (Willd.) Miers, Withania somnifera (L.) Dunal, Scutellaria baicalensis Georgi, Curcuma longa L. etc. TCM was shown to be utilized with over 90% efficacy when the COVID-19 pandemic broke out in early 2020. In addition to herbal treatments and nutraceutical drugs, dietary supplements such as vitamins and amino acid derivatives also play a significant part in COVID-19 management. Diet can assist in regulating inflammation, while nutraceuticals can aid in the prevention of viral invasion. Functional amino acids (e.g., arginine, cysteine, glutamate, glutamine, glycine, taurine, and tryptophan) and glutathione, which are all abundant in animal-sourced foodstuffs, are crucial for optimum immunity and health in humans and animals. The goal of this article is to thoroughly evaluate recent statistics on the effectiveness of herbal medicines in COVID-19, the antiviral activity of nutraceuticals, and the significance of these results in creating dietary supplements that would enhance innate immunity and contribute as preventive measures against severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2).

Common genetic aspects between COVID-19 and sarcoidosis: A network-based approach using gene expression data

The pandemic situation of novel coronavirus disease 2019 (COVID-19) is a global threat on our current planet, with its rapid spread and high mortality rate. Sarcoidosis patients are at high risk to COVID-19 severity for having lung injuries as well as treating with immunosuppressive agents. So, physicians are in dilemma whether they should use immunosuppressive agents or not for the patients with sarcoidosis history and COVID-19 infection. Therefore, common factors should be identified to provide effective treatment. For determining the common genes between COVID-19 and sarcoidosis, GSE164805 and GSE18781 were retrieved from the Gene Expression Omnibus (GEO) database. Common upregulated genes were identified by using R language to investigate their involved pathways and gene ontologies (GO). With the aid of the STRING Cytoscape plugin tool, protein-protein interactions (PPIs) network was constructed. From the PPIs network, Hub genes and essential modules were detected by using Cytohubba, and MCODE respectively. For hub genes, TFs, TFs-miRNA, and drug, interaction networks were built through the NetworkAnalyst web platform. A total of 34 common upregulated genes were identified and among them, five hub genes, including TET2, MUC5AC, VDR, NFE2L2, and BCL6 were determined. In addition, a cluster having VDR and NFE2L2 was detected from the PPIs network. Moreover, 32 transcription factors and 9 miRNA were recognized for hub genes. Furthermore, vitamin D and some of its analogous compounds were obtained from the drug interaction network. In conclusion, hub genes identified in this study might have potential roles in modulating COVID-19 infection and sarcoidosis. However, further studies are required to corroborate this study.

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Sarcoidosis patients are at high risk to COVID-19 severity.

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This study aimed to find out common genetic factors for COVID-19 and Sarcoidosis.

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34 common upregulated genes were identified from GSE164805 and GSE18781 datasets.

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From common upregulated genes, five hub genes, VDR, NFE2L2, BCL6, TET2, and MUC5AC, were recognized.

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Hub genes associated with miRNA, TFs, and drug molecules were also identified.

Co-encapsulation of vitamin D and rutin in chitosan-zein microparticles

There is a growing interest in co-encapsulating multiple species to harness potential synergy between them, enhance their stability and efficacy in various products. The aim of this work was to co-encapsulate vitamin D3 and rutin inside chitosan-zein microparticles using a simple and easily scalable process for food fortification. This was achieved via anti-solvent precipitation coupled with spray-drying. Free-flowing powders of spherical microparticles with wrinkled surface and particle size < 10 μm were obtained. The encapsulation efficiency was 75% for vitamin D3 and 44% for rutin and this could be attributed to their different molecular size and affinity to the aqueous phase. The physicochemical properties were characterized by X-Ray powder diffraction and Fourier transform infrared spectroscopy. The two crystalline bioactive compounds were present in the microparticles in amorphous form, which would allow for better bioavailability when compared to non-encapsulated crystalline solid. Therefore, the obtained microparticles would be suitable for use as food ingredient for vitamin D3 fortification, with the co-encapsulated rutin acting as stability and activity enhancer.

Is There a Crucial Link Between Vitamin D Status and Inflammatory Response in Patients With COVID-19?

Background

Hypovitaminosis D has been suggested to play a possible role in coronavirus disease 2019 (COVID-19) infection.

Methods

The aim of this study is to analyze the relationship between vitamin D status and a biochemical panel of inflammatory markers in a cohort of patients with COVID-19. A secondary endpoint was to evaluate the correlation between 25OHD levels and the severity of the disease. Ninety-three consecutive patients with COVID-19-related pneumonia were evaluated from March to May 2020 in two hospital units in Pisa, in whom biochemical inflammatory markers, 25OHD levels, P/F ratio at nadir during hospitalization, and complete clinical data were available.

Results

Sixty-five percent of patients presented hypovitaminosis D (25OHD ≤ 20 ng/ml) and showed significantly higher IL-6 [20.8 (10.9-45.6) vs. 12.9 (8.7-21.1) pg/ml, p = 0.02], CRP [10.7 (4.2-19.2) vs. 5.9 (1.6-8.1) mg/dl, p = 0.003], TNF-α [8.9 (6.0-14.8) vs. 4.4 (1.5-10.6) pg/ml, p = 0.01], D-dimer [0.53 (0.25-0.72) vs. 0.22 (0.17-0.35) mg/l, p = 0.002], and IL-10 [3.7 (1.8-6.9) vs. 2.3 (0.5-5.8) pg/ml, p = 0.03]. A significant inverse correlation was found between 25OHD and all these markers, even adjusted for age and sex. Hypovitaminosis D was prevalent in patients with severe ARDS, compared with the other groups (75% vs. 68% vs. 55%, p < 0.001), and 25OHD levels were lower in non-survivor patients.

Conclusions

The relationship between 25OHD levels and inflammatory markers suggests that vitamin D status needs to be taken into account in the management of these patients. If vitamin D is a marker of poor prognosis or a possible risk factor with beneficial effects from supplementation, this still needs to be elucidated.

Formation of ideas about rational nutrition as an element of student’s environmental education

The aim of the work was to form ideas about rational nutrition as an element of ecological education of students by studying and discussing their eating behavior in relation to foods rich in vitamin D using quantitative descriptor-profile analysis. Quantitative descriptor-profile analysis showed that the “poorest” profiles have foods with the highest vitamin D. Thus, foods with a high vitamin D content do not fall into the circle of students’ dietary preferences. The results of the survey showed that the most frequently consumed foods for young people are fried potatoes, pizza, dumplings and cheese. Products such as cheese, butter, artificial red caviar, mushrooms (chanterelles) can be successfully used as a base for fortification with vitamin D, since they are positively perceived by students and affordable. It was shown that cheese is the only product that, when surveyed by 59 young people, was included both in the list of 5 most favorite and frequently consumed foods, and was selected from the list of 22 foods offered to the respondents containing significant amounts of vitamin D. The research carried out is the basis for forming students’ understanding of the importance of a balanced diet in the context of environmental education.

Vitamin D Dosing: Basic Principles and a Brief Algorithm (2021 Update)

Nowadays, in modern societies, many people can be at high risk to have low vitamin D levels. Therefore, testing of serum 25-hydroxy-vitamin D (25OH-D) levels should be performed before prescribing them vitamin D supplementation. However, in some cases the 25OH-D level assessment is not available at the right moment, e.g., due to mandatory quarantine of COVID-19 outpatients. Therefore, such patients could be advised to start taking moderate vitamin D doses (e.g., 4000 IU/day for adults), and their 25-OH-D levels could be checked later. The proposed algorithm also comprises vitamin D dosing principles when baseline 25OH-D levels are known.

Interleukin-37 is down-regulated in serum of patients with severe coronavirus disease 2019 (COVID-19)

Pro-inflammatory and anti-inflammatory cytokines are indicated to play a prominent role in mediating the immunopathogenesis of coronavirus disease 19 (COVID-19). Interleukin (IL-37) is one of the anti-inflammatory cytokines that has been proposed to be involved in disease progression but the data are not overwhelming. Therefore, a case-control study was performed to analyze IL-37 levels in serum of 100 patients with severe COVID-19 and 100 blood donors (control group). Median age was significantly higher in COVID-19 cases than in controls. Stratification by gender, body mass index and ABO and Rh blood group systems showed no significant differences between patients and controls. Chronic diseases (cardiovascular and diabetes) were observed in 57.0% of patients. Serum levels of IL-37 and vitamin D were significantly decreased in patients compared to controls. The low level of IL-37 was more pronounced in males, overweight/obese cases, blood group B or AB cases, Rh-positive cases, and cases with no chronic disease. Low producers of IL-37 were more likely to develop COVID-19 (odds ratio = 2.66; 95% confidence interval = 1.51-4.70; corrected probability = 0.015). Receiver operating characteristic curve analysis demonstrated that a low serum level of IL-37 was a good predictor of COVID-19. Spearman's rank correlation analysis showed that IL-37 and vitamin D were significantly correlated. In conclusion, IL-37 was down-regulated in serum of patients with severe COVID-19 compared to controls. This down-regulation may be associated with an increased risk of disease. Gender, body mass index, blood groups and chronic disease status may also affect IL-37 levels.

Vitamin D: Dosing, levels, form, and route of administration: Does one approach fit all?

The 4th International Conference on Controversies in Vitamin D was held as a virtual meeting in September, 2020, gathering together leading international scientific and medical experts in vitamin D. Since vitamin D has a crucial role in skeletal and extra-skeletal systems, the aim of the Conference was to discuss improved management of vitamin D dosing, therapeutic levels and form or route of administration in the general population and in different clinical conditions. A tailored approach, based on the specific mechanisms underlying vitamin D deficiency in different diseases that were discussed, was recommended. Specifically, in comparison to healthy populations, higher levels of vitamin D and greater amounts of vitamin D were deemed necessary in osteoporosis, diabetes mellitus, obesity (particularly after bariatric surgery), and in those treated with glucocorticoids. Emerging and still open issues were related to target vitamin D levels and the role of vitamin D supplementation in COVID-19 since low vitamin D may predispose to SARS-CoV-2 infection and to worse COVID-19 outcomes. Finally, whereas oral daily cholecalciferol appears to be the preferred choice for vitamin D supplementation in the general population, and in most clinical conditions, active vitamin D analogs may be indicated in patients with hypoparathyroidism and severe kidney and liver insufficiency. Parenteral vitamin D administration could be helpful in malabsorption syndromes or in states of vitamin D resistance.Specific guidelines for desired levels of vitamin D should be tailored to the different conditions affecting vitamin D metabolism with the goal to define disease-specific normative values.

Accuracy of Machine Learning Models to Predict Mortality in COVID-19 Infection Using the Clinical and Laboratory Data at the Time of Admission

Aim

This study aimed to develop a predictive model to predict patients’ mortality with coronavirus disease 2019 (COVID-19) from the basic medical data on the first day of admission.

Methods

The medical data including the demographic, clinical, and laboratory features on the first day of admission of clinically diagnosed COVID-19 patients were documented. The outcome of patients was also recorded as discharge or death. Feature selection models were then implemented and different machine learning models were developed on top of the selected features to predict discharge or death. The trained models were then tested on the test dataset.

Results

A total of 520 patients were included in the training dataset. The feature selection demonstrated 22 features as the most powerful predictive features. Among different machine learning models, the naive Bayes demonstrated the best performance with an area under the curve of 0.85. The ensemble model of the naive Bayes and neural network combination had slightly better performance with an area under the curve of 0.86. The models had relatively the same performance on the test dataset.

Conclusion

Developing a predictive machine learning model based on the basic medical features on the first day of admission in COVID-19 infection is feasible with acceptable performance.

Ultraviolet-A light increases mitochondrial anti-viral signaling protein in confluent human tracheal cells via cell-cell signaling

Mitochondrial antiviral signaling (MAVS) protein mediates innate antiviral responses, including responses to certain coronaviruses such as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We have previously shown that ultraviolet-A (UVA) therapy can prevent virus-induced cell death in human ciliated tracheal epithelial cells (HTEpC) infected with coronavirus-229E (CoV-229E), and results in increased intracellular levels of MAVS. In this study, we explored the mechanisms by which UVA light can activate MAVS, and whether local UVA light application can activate MAVS at locations distant from the light source (e.g. via cell-to-cell communication). MAVS levels were compared in HTEpC exposed to 2 mW/cm² narrow band (NB)-UVA for 20 min and in unexposed controls at 30–40% and at 100% confluency, and in unexposed HTEpC treated with supernatants or lysates from UVA-exposed cells or from unexposed controls. MAVS was also assessed in different sections of confluent monolayer plates where only one section was exposed to NB-UVA. Our results showed that UVA increases the expression of MAVS protein. Further, cells in a confluent monolayer exposed to UVA conferred an elevation in MAVS in cells adjacent to the exposed section, and also in cells in the most distant sections which were not exposed to UVA. In this study, human ciliated tracheal epithelial cells exposed to UVA demonstrate increased MAVS protein, and also appear to transmit this influence to confluent cells not exposed to UVA, likely via cell-cell signaling.

Italian Public Health Expenditure for Vitamin D is still high: New Outlook to Saving From a Consumption Analysis in the Liguria Region

PURPOSE

Italian expenditure for vitamin D greatly increased in the last few years, reaching €314 million ($376.8 million) in 2019. In Italy, the main cause of the increase in public spending for vitamin D is the marketing of high-cost medicines. At national and regional levels, some interventions have been performed to reduce expenditure, but spending has continued to increase. The aim of this work is to propose a new saving strategy determined by an analysis of a significant sample of the market.

METHODS

Data on the use of vitamin D formulations, including data for the different active substances that represent its pharmaceutical analogue and composition of groups of equivalence, were extrapolated from the Italian Medicines Agency transparency lists and from the Farmadati database. Data on pharmaceutical expenditure were obtained from the Data Warehouse of Liguria Region; the composition of this expenditure was analyzed in detail, focusing on the characteristics of the pharmaceutical preparations and their cost (price per defined daily dose).

FINDINGS

Vitamin D expenditure paralleled that of cholecalciferol, the most used active ingredient, which in Liguria increased from €643,352 ($772,022.4) in 2010 to €8,006,574 ($9,607,888.8) in 2019 (increase of 1144%). Spending focused on high-cost formulations, exceeding 90% of total cholecalciferol cost in 2019. We simulated a possible optimization of the expense for cholecalciferol by applying a revised price to all the cholecalciferol consumptions in high-cost products because these formulations do not have an added therapeutic value, finding that the saving would be at least 60%. National data on the detailed expenditure composition for vitamin D are not available, but we found a strong resemblance between total cholecalciferol expenditure time series in Italy and the Liguria Region.

IMPLICATIONS

The expense of cholecalciferol and consequently the expense of vitamin D could be optimized by modifying the reimbursement of high-cost formulations. At a national level, savings should be proportional to that estimated for the Liguria Region. On the basis of the 2019 data, Italian savings with respect to total cholecalciferol expenditure should be €170.65 million ($204.78 million); per capita cholecalciferol expenditure would shift from €4.66 ($5.59) to €1.84 ($2.21).

Vitamin D Deficiency Is Associated With Higher Hospitalization Risk From COVID-19: A Retrospective Case-control Study

CONTEXT

One risk factor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is postulated to be vitamin D deficiency. To better understand the role of vitamin D deficiency in the disease course of COVID-19, we undertook a retrospective case-control study in North West England.

OBJECTIVE

To examine whether hospitalization with COVID-19 is more prevalent in individuals with lower vitamin D levels.

METHODS

The study included individuals with test results for serum 25-hydroxyvitamin D (25[OH]D) between April 1, 2020, and January 29, 2021, from 2 districts in North West England. The last 25(OH)D level in the previous 12 months was categorized as "deficient" if less than 25 nmol/L and "insufficient" if 25 to 50 nmol/L.

RESULTS

The study included 80 670 participants. Of these, 1808 were admitted to the hospital with COVID-19, of whom 670 died. In a primary cohort, median serum 25(OH)D in nonhospitalized participants with COVID-19 was 50.0 nmol/L (interquartile range [IQR], 34.0-66.7) vs 35.0 nmol/L (IQR, 21.0-57.0) in those admitted with COVID-19 (P < 0.005). In a validation cohort, median serum 25(OH)D was 47.1 nmol/L (IQR, 31.8-64.7) in nonhospitalized vs 33.0 nmol/L (IQR, 19.4-54.1) in hospitalized patients. Age-, sex-, and season-adjusted odds ratios for hospital admission were 2.3 to 2.4 times higher among participants with serum 25(OH)D <50 nmol/L compared with those with normal serum 25(OH)D levels, without excess mortality risk.

CONCLUSION

Vitamin D deficiency is associated with higher risk of COVID-19 hospitalization. Widespread measurement of serum 25(OH)D and treatment of insufficiency or deficiency may reduce this risk.

The role of vitamin D in prevention OF COVID-19 and its severity: an umbrella review

BACKGROUND AND AIM

Vitamin D is known to modulate immune response and its deficiency was associated with respiratory distress in patients hospitalized for pneumonia. Nevertheless, numerous reviews on vitamin D in COVID-19 patients have shown conflicting results, as previously reported also for other respiratory diseases (e.g., influenza).

METHODS

This umbrella review aims to assess whether low serum 25-OHD is associated with susceptibility to COVID 19, their severity, and mortality. A total of 1559 studies were excluded after the title, abstract and full-text articles screening and 9 papers were included in this review: 2 systematic reviews and 7 metanalysis.

RESULTS

The findings of this review that summarized studies from 5 WHO regions (European Region, Region of the Americas, South-East Asia Region, Eastern Mediterranean Region, Western Pacific Region) to exclusion only African region, show that low serum 25-OHD levels are associated with higher infection risks for COVID-19.

CONCLUSIONS

Although the umbrella findings indicate a potential role of vitamin D deficiency in COVID-19 severity in hospitalized patients and showing an association between Vitamin D supplementation and COVID-19 severity, however, more robust data from randomized controlled trials are further needed to confirm a possible association with the mortality rates.

The Complex Interplay between Immunonutrition, Mast Cells, and Histamine Signaling in COVID-19

There is an ongoing need for new therapeutic modalities against SARS-CoV-2 infection. Mast cell histamine has been implicated in the pathophysiology of COVID-19 as a regulator of proinflammatory, fibrotic, and thrombogenic processes. Consequently, mast cell histamine and its receptors represent promising pharmacological targets. At the same time, nutritional modulation of immune system function has been proposed and is being investigated for the prevention of COVID-19 or as an adjunctive strategy combined with conventional therapy. Several studies indicate that several immunonutrients can regulate mast cell activity to reduce the de novo synthesis and/or release of histamine and other mediators that are considered to mediate, at least in part, the complex pathophysiology present in COVID-19. This review summarizes the effects on mast cell histamine of common immunonutrients that have been investigated for use in COVID-19.

Prognostic Role of Metabolic Syndrome in COVID-19 Patients: A Systematic Review Meta-Analysis

Background: The prevalence and prognostic implications of metabolic syndrome (MetS) in patients infected by the SARS-CoV-2 remain unclear. We performed a systematic review and meta-analysis of prevalence and mortality risk in COVID-19 patients with MetS. Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in abstracting data and assessing validity. We searched MEDLINE and Scopus to locate every article published up to 1 September 2021, reporting data on MetS among COVID-19 patients. The pooled prevalence of MetS was calculated using a random effects model and presented using the related 95% confidence interval (CI), while the mortality risk was estimated using the Mantel-Haenszel random effects models with odds ratio (OR) and related 95% CI. Statistical heterogeneity was measured using the Higgins I² statistic. Results: Six studies, enrolling 209.569 COVID-19 patients [mean age 57.2 years, 114.188 males (54.4%)] met the inclusion criteria and were included in the final analysis. The pooled prevalence of dyslipidaemia was 20.5% of cases (95% CI: 6.7–47.8%, p = 0.03), with high heterogeneity (I² = 98.9%). Pre-existing MetS was significantly associated with higher risk of short-term mortality (OR: 2.30, 95% CI: 1.52–3.45, p < 0.001), with high heterogeneity (I² = 89.4%). Meta-regression showed a direct correlation with male gender (p = 0.03), hypertension (p < 0.001), DM (p = 0.01) and hyperlipidaemia (p = 0.04), but no effect when considering age (p = 0.75) and chronic pulmonary disease (p = 0.86) as moderators. Conclusions: MetS represents a major comorbidity in about 20% of COVID-19 patients and it is associated with a 230% increased risk of short-term mortality.

Vitamin D in infectious complications in critically ill patients with or without COVID-19

25-hydroxyvitamin D [25(OH)D] is an important immunomodulator, whose deficiency may aggravate the incidence and outcome of infectious complications in patients admitted to the intensive care unit. The most recognized extra-skeletal action of vitamin D is the regulation of immune function. Host defense against intracellular pathogens depends upon both innate and adaptive immunity. It has been suggested that vitamin D regulates the pro-inflammatory endothelial response to lipopolysaccharide, rendering it a role in the sepsis cascade. Recent studies have indicated that vitamin D deficiency may be associated with worse outcomes in patients with coronavirus disease 2019 (COVID-19), such as more severe disease and higher mortality rates. To this end, clinical trials with vitamin D supplementation are being carried out in an effort to improve COVID-19 outcomes. In this review, we will discuss the role of vitamin D in the immune response, and more specifically its effect on immune cells. Subsequently, we will provide an overview of the studies that have investigated the predictive value of vitamin D in critical illness outcomes, and its therapeutic value as a supplement in critically ill patients. Finally, the emerging role of vitamin D deficiency in COVID-19 infection risk, and worse outcomes will be discussed.