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Article

Vitamin D Status and SARS-CoV-2 Positivity in Lebanon Among Adults: A Cross-Sectional Study in South Lebanon

by
Ahmed A. Madar
1,*,
Firass Al Lababidi
1,
Filali Samia
2 and
Haakon E. Meyer
1,3
1
Department of Community Medicine and Global Health, Institute of Health and Society, University of Oslo, 0318 Oslo, Norway
2
Hammoud Hospital Medical Center, Sidon P.O. Box 652, Lebanon
3
Physical Health and Ageing, Norwegian Institute of Public Health, 0213 Oslo, Norway
*
Author to whom correspondence should be addressed.
COVID 2025, 5(7), 97; https://doi.org/10.3390/covid5070097
Submission received: 25 March 2025 / Revised: 18 June 2025 / Accepted: 19 June 2025 / Published: 27 June 2025
(This article belongs to the Special Issue COVID and Public Health)
Versions Notes

Abstract

Background: The COVID-19 pandemic has affected countries globally, causing significant respiratory tract symptoms, including shortness of breath, coughing, chest tightness, and wheezing. Vitamin D has been proposed to play a key role, especially in upper respiratory tract infections. Recently, numerous studies and reports associating low serum 25-hydroxyvitamin D levels (s-25-(OH)D) and adverse outcomes in COVID-19 have emerged. We aimed to assess the association between vitamin D status and SARS-CoV-2 positivity among adults in Lebanon. Method: A cross-sectional study was conducted, recruiting 384 participants aged 18–75 years from a university hospital in South Lebanon. Background variables were collected through structured questionnaires. Serum 25(OH)D levels were measured using electrochemiluminescence immunoassay, and SARS-CoV-2 positivity was assessed through PCR testing. Results: The mean s-25(OH)D level was 46.8 nmol/L (SD 28.1), and 30% of the participants had vitamin D deficiency (s-25-(OH)D level <30 nmol/L). SARS-CoV-2 positivity was reported in 28% of participants. However, no significant association was found between s-25(OH)D levels and SARS-CoV-2 positivity. This study had several limitations, including potential selection bias due to recruiting participants from a hospital for PCR testing, the collection of data across different seasons, and the refusal of several eligible individuals to participate. Additionally, the lack of data on participants’ immunization status and assay variability may impact the generalizability and interpretation of the findings. Conclusion: There was a high prevalence of vitamin D insufficiency among adults participating in COVID-19 tests in Lebanon, but it was not associated with SARS-CoV-2 positivity.

1. Introduction

COVID-19, caused by the SARS-CoV-2 virus, was declared a global pandemic by the World Health Organization (WHO) in March 2020 [1]. As of now, WHO statistics report over 521 million confirmed cases and more than 6 million deaths globally [2]. The pandemic has led to significant research efforts to understand risk factors, develop treatment options, create vaccines, and identify prognostic markers [3]. Among these, vitamin D has drawn attention for its potential role in modulating immune responses and reducing the risk of respiratory infections [4,5,6].
Vitamin D is a fat-soluble vitamin essential for calcium homeostasis and bone health, but it also has roles in regulating the immune system. It has been shown to modulate both innate and adaptive immune responses, reducing excessive inflammatory reactions while enhancing the body’s ability to fight infections [7,8]. Of particular interest is its potential to prevent upper respiratory tract infections. Studies suggest that maintaining adequate vitamin D levels may reduce the risk of these infections by boosting antimicrobial peptide production and modulating inflammation [9].
Emerging evidence also suggests a potential link between vitamin D status and COVID-19 outcomes. Observational studies have reported that individuals with lower vitamin D levels may be at higher risk for severe COVID-19, including outcomes such as hospitalization, ICU admission, and mortality [10,11,12,13]. However, findings have been inconsistent, and significant gaps remain in understanding whether vitamin D directly influences COVID-19 severity or if it is merely a marker of other health conditions [14]. Additionally, much of the research has focused on populations in Europe and North America, leaving a knowledge gap about regions like the Middle East, where both COVID-19 and vitamin D deficiency are prevalent.
Lebanon, a country facing severe socioeconomic challenges and financial instability, has been significantly affected by the pandemic [15]. According to the Ministry of Public Health (MOPH), the country has recorded over 1 million confirmed COVID-19 cases and 10,400 deaths. Vaccination rates remain low, with only 35% of the population receiving two doses and 24% receiving three doses [16]. Compounding this crisis, studies report a high prevalence of vitamin D deficiency among Lebanese adults [17], likely due to dietary patterns, limited sun exposure, and socioeconomic factors.
Our study aims to address the relationship between vitamin D status and SARS-CoV-2 positivity in Lebanon. By examining this association, we seek to contribute to the broader discussion on vitamin D’s potential role in mitigating respiratory infections, particularly in vulnerable populations like those in Lebanon. Identifying such links could offer valuable insights for public health interventions, including the potential benefits of vitamin D supplementation in regions with high deficiency rates and a significant COVID-19 burden.
We hypothesized that persons with insufficient or deficient vitamin D levels are more likely to test positive for SARS-CoV-2 compared to individuals with sufficient vitamin D levels. Vitamin D insufficiency has been associated with increased susceptibility to respiratory infections, including influenza and other coronaviruses; therefore, the hypothesis is biologically plausible and supported by immune pathway data and observational trends, even if causal evidence remains inconclusive.

2. Materials and Methods

2.1. Study Design and Participants

Participants were recruited between 23 November 2021, and 30 April 2022, from Hammoud Hospital University Medical Center in Sidon, a facility serving more than 24,000 residents annually. The hospital is the primary university medical center in the southern region, serving as a central hub for residents. All individuals visiting the hospital for COVID-19 PCR testing had an equal opportunity to participate in the study. The study included individuals who underwent PCR testing and met the eligibility criteria. The sample size was calculated using the Cochran formula, considering a desired level of precision, a specific confidence level, and the estimated proportion of the attribute of interest in the population, resulting in a sample size of 384.
  • Inclusion and exclusion criteria
Inclusion criteria included residents of Lebanon aged 21–75 years, given their susceptibility to COVID-19, who were able to understand Arabic or English and provide informed consent. Illiterate participants were assisted by a study moderator to provide either a fingerprint or signature for consent. Additionally, participants were required to stand to ensure accurate measurements of weight and height. Exclusion criteria included individuals with severe COVID-19 and those taking vitamin D supplements for more than three months.
  • Ethical consideration
All participants provided informed consent, and the study received ethical approval from the Regional Community for Medical and Health Research Ethics (REK) in Norway (study code: 270246), the Norwegian Research Center for Research Data (NSD) (study code: 513677), and the Institutional Review Board (IRB) of Hammoud Hospital University Medical Center (study code: 26082021). To ensure data integrity and quality control, several measures were implemented throughout the data collection and analysis process. Standardized protocols and instruments were used to maintain consistency, and automated data checks helped identify and correct errors or inconsistencies. All data was stored and managed in a secured platform (TSD: Service for Sensitive Data).
Participants who tested positive for COVID-19 were contacted by the hospital and informed about the Lebanese Ministry of Public Health (MOPH) quarantine guidelines. Each participant received written feedback on their vitamin D levels. Those with severe vitamin D deficiency (<12.5 nmol/L) were advised to improve their vitamin D status and referred to their local health centers.
A random sample of 10% of the dataset was manually checked for accuracy. Data entry and analysis were performed using SPSS Version 28.0.01.

2.2. Survey Instrument and Anthropometric Measurements

An interview-administered questionnaire was used by a study moderator using a hospital-provided tablet device with a direct link to the University of Oslo’s platform for storing and processing sensitive research data. The questionnaire addressed the following aspects: age, gender, educational level, and finally the previous history of COVID-19 infection.
  • Anthropometric measurements
Height and weight were both measured using a scale that was calibrated every day (using SECA 220-FS308). Overweight and obese were defined as BMI ≥25 and ≥30 kg/m2, respectively.

2.2.1. COVID-19 Testing and Blood Testing

The COVID-19 testing was conducted at Hammoud Hospital University Medical Center using a combined throat and nose swabbing technique and analyzed by Biofire Diagnostics BioFire FilmArray, Cepheid GeneXpert and BMS Mic PCR. Blood samples were drawn from the study participants to test for s-25(OH)D using the Roche Cobas e411 Analyzer (Roche Diagnostics, Basel, Switzerland) and Abbot Architect Plus Ci4100 (Abbott Laboratories, Abbott Park, IL, USA) using the electrochemiluminescence immunoassay method. Calibration and cross-calibration for both methods happened every 3 months per the manufacturing company guidelines and internal hospital policies.

2.2.2. Vitamin D Status

A common universal normal range for s-25(OH)D was not agreed upon. However, we chose to use the cut-offs proposed by the Institute of Medicine as levels of <12.5 nmol/L for severe deficiency, ≥12.5–29.9 nmol/L for deficiency, 30–50 nmol/L for insufficiency and ≥50 nmol/L for adequate levels [18].

2.3. Statistical Methods

Descriptive statistics included frequencies and percentages for categorical variables and mean and standard deviation for continuous variables. Comparisons between men and women regarding sociodemographic variables, factors related to s-25(OH)D levels, and COVID-19 status were conducted using chi-square tests for categorical variables and independent sample t-tests for continuous variables. Statistical significance was set at p < 0.05.
Logistic regression was performed with SARS-CoV-2 positivity as the dependent variable and s-25(OH)D levels categorized into deficiency (combination of severe deficiency and deficiency), insufficiency and sufficiency as the independent variable. Adjustments were made for age, gender, BMI, and education level.

3. Results

Out of 385 participants who were invited, data were collected from 384 eligible participants. One participant aged more than 75 years was excluded. Characteristics of the study population are shown in Table 1.

3.1. Sociodemographic Characteristics of the Sample

The mean age was 38.8 years old (SD 12.4), and there were 175 men (45.6%) and 209 women (54.4%). Regarding the education status of the participants, most of them (62.8%) had a university degree, whereas 22.9% had a secondary degree and 14.3% had elementary school or less. Generally, men had higher levels of education than women, but this difference was not statistically significant. The mean BMI of the participants was 27.1 (SD 5) kg/m2 and men had significantly higher BMI than women (p < 0.001).
The mean s-25(OH)D level was 46.8 nmol/L (SD 28.1). Although women had slightly higher levels (49.2 nmol/L) compared to men (44.0 nmol/L), the difference was not statistically significant (p = 0.07). Approximately one-third of the participants had vitamin D deficiency (s-25(OH)D) <30 nmol/L).
Previous infection with SARS-CoV-2 was reported by 44% of the participants (32% with and 12% without PCR confirmation).
No significant differences were observed in the reporting of previous SARS-CoV-2 infection in men versus women (p = 0.65). All the participants took PCR testing at Hammoud Hospital University Medical Center, and 28% had positive results. There was no gender difference in the proportion with a positive PCR test (p = 0.53).
An inverse relationship appears to be observed for SARS-positivity, with 21.4% of women testing positive compared to 48% of men at middle levels of vitamin D, and 21% versus 41%, respectively, at higher levels (Table 2).
Higher SARS-CoV-2 positivity rates were generally observed among individuals with vitamin D deficiency, especially among those with lower education levels and younger age groups. Higher BMIs were observed in some deficient and insufficient groups, particularly among women aged 30–49 with vitamin D insufficiency. Although only descriptive stratifications were performed and interaction terms were not tested, these findings suggest inconsistency across the different subgroups analyzed (Supplementary Table S1).

3.2. Association Between s-25(OH)D Levels and SARS-CoV-2 Positivity

Our analysis demonstrated no statistically significant association between s-25(OH)D levels and SARS-CoV-2 positivity. After adjusting for age, BMI, gender, and education levels, the odds of having SARS-CoV-2 positivity were 1.5 higher among those with vitamin D deficiency compared to those with vitamin D sufficiency (Table 3).

4. Discussion

In this study, we hypothesized that vitamin D status might be associated with SARS-CoV-2 positivity. However, our findings revealed no statistically significant association between vitamin D status and SARS-CoV-2 positivity. Our findings align with previous studies that have found no direct association between vitamin D levels and susceptibility to COVID-19 infection [19,20,21,22,23]. These findings contrast with other research indicating a potential protective role for vitamin D in reducing the severity of respiratory infections and COVID-19 [24,25]. Even though 63% of the participants had a vitamin D insufficiency (s-25(OH)D <50 nmol/L), our study did not demonstrate any significant impact on SARS-CoV-2 positivity.
To better understand the potential factors influencing this relationship, we explored sociodemographic variables such as gender, age, education, and BMI. While gender has been hypothesized to influence the link between vitamin D and COVID-19 [26], our study found no association between gender and SARS-CoV-2 positivity. This study agreed with findings by AlQuaiz et al., which reported a higher prevalence of vitamin D deficiency in males [27]. Other studies have noted that male COVID-19 cases are often more severe than female cases [28], possibly due to biological differences, although the mechanism remains unclear. Similarly, while aging is recognized as a significant risk factor for severe disease and mortality [29], no association between age and SARS-CoV-2 positivity was found in our study.
Educational level has also been linked to differences in COVID-19 outcomes and vaccination willingness [30,31]. While lower education levels have been associated with increased COVID-19 severity, our study found no significant association between educational level and vitamin D status or SARS-CoV-2 positivity, even after adjustments [28,29,32]. Similarly, BMI, which is often linked to reduced circulating vitamin D levels [33], did not influence the association between vitamin D and SARS-CoV-2 positivity in our analysis.
Although our findings did not show a significant direct link between vitamin D status and SARS-CoV-2 positivity, previous studies have highlighted the potential protective role of vitamin D in mitigating severe outcomes of COVID-19, such as hospitalization, ICU admission, and mortality. For instance, a study in the Philippines reported that patients with s-25(OH)D levels of 20–30 ng/mL and <20 ng/mL were 12 and 19 times more likely to die from COVID-19, respectively, compared to those with sufficient levels [34]. A recent systematic review and meta-analysis further supports the role of vitamin D in reducing the risk of respiratory infections, particularly in individuals with severe deficiency [35]. However, randomized controlled trials have, in general, not supported an effect of vitamin D on COVID-19 [22].

Strength and Limitations

To our knowledge, this is the first study exploring the relationship between vitamin D status and SARS-CoV-2 positivity in Lebanon. The recruitment and data collection were performed by the same researcher and both women and men are equally represented in the study.
However, there are several limitations. First, the participants were recruited from a hospital setting where they underwent a PCR test; this may introduce selection bias, as the study might disproportionately represent individuals with greater health awareness or access to healthcare. Another selection bias could have occurred because several eligible people declined to participate (participation rate 78.8%). On the other hand, a comparison of the education levels of included participants to national education figures (62.8% among study participants vs. 60.79% national average) suggests that the participants in this present study might possibly be representative of men and women of the same age in Lebanon [36]. The lack of immunization data is a major limitation, particularly given that the study period coincided with the COVID-19 vaccine rollout. Another possible limitation is that we do not have information on those who refused to participate and seasonal variation in vitamin D. Furthermore, although the analysis was performed in one batch, s-25(OH)D was collected in different seasons, which may have affected the levels. Due to assay variability, it might be difficult to differentiate the categories of mild or moderate deficiency in our study participants. In sum, all these limitations may have biased results, and therefore our results should be interpreted with caution concerning the generalizability of the findings.

5. Conclusions

There was a high prevalence of vitamin D insufficiency among adult participants, but s-25(OH)D was not associated with SARS-CoV-2 positivity. Further research is necessary to investigate the health consequences of poor s-25(OH)D status in this population, particularly across different age groups. Further research is necessary to assess the potential impact of vitamin D on COVID-19 severity and outcomes.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/covid5070097/s1, Table S1: SARS-CoV-2 positivity and BMI gender, age, and education level with vitamin D levels.

Author Contributions

Conceptualization, A.A.M.; data curation, F.A.L. and A.A.M.; formal analysis, A.A.M., H.E.M. and F.A.L.; methodology, H.E.M., A.A.M. and F.A.L.; project administration, F.A.L. and A.A.M.; supervision, A.A.M. and F.S.; visualization, A.A.M. and F.A.L.; writing—original draft, F.A.L.; resources, A.A.M.; writing—review and editing, A.A.M., F.A.L., H.E.M. and F.S. All authors have read and agreed to the published version of the manuscript.

Funding

This study has been funded by the University of Oslo, Faculty of Medicine, Department of International Community Health, under the grant HELSAM-13103000.

Institutional Review Board Statement

The study was approved by the Regional Community for Medical and Health Research Ethics (REK) in Norway (study code: 270246), the Norwegian Research Center for Research Data (NSD) (study code: 513677), and finally, the Hammoud Hospital University Medical Center Institutional Review Board (IRB) (study code: 26082021).

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

Data can be provided upon request.

Acknowledgments

We would like to send special thanks to Sarah Chamseddine for her amazing help in interviewing participants at Hammoud University Medical Center, completing the questionnaires, conducting the height and weight measurements, and coordinating with the laboratory technicians for conducting both COVID-19 tests and s-25(OH)D tests.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

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Table 1. Sociodemographic characteristics of the study population (N = 384).
Table 1. Sociodemographic characteristics of the study population (N = 384).
VariablesWomenMenAllMales vs. Females p-Value
Gender54.4% (209)45.6% (175)100.0% (384)-
Age Categories, % (n)
21–29 years
30–49 years
50–75 years		31.1% (65)
45.5% (95)
23.4% (49)		22.9% (40)
61.1% (107)
16.0% (28)		27.3% (105)
52.6% (202)
20.1% (77)		0.63
Education years, % (n)
Elementary school or less
Secondary school
Tertiary education		16.3% (34)
19.6% (41)
64.1% (134)		12.0% (21)
26.9% (47)
61.1% (107)		14.3% (55)
22.9% (88)
62.8% (241)		0.17
Weight (kg), mean (SD)69.2 (14.7)86.8 (16.2)77.2 (17.7)<0.001
Height (cm), mean (SD)161.9 (6.2)176.3 (7.3)168.4 (9.8)<0.001
BMI Categories, % (n)
Normal (<25 kg/m2)
Overweight (25–29.9 kg/m2)
Obese (≥30 kg/m2)		45.0% (94)
29.7% (62)
22.0% (46)		30.9% (54)
38.3% (67)
30.8% (54)		38.5% (148)
33.6% (129)
26.0% (100)		<0.001
Table 2. s-25(OH)D levels, self-reported infection with SARS-CoV-2 and SARS-CoV-2 PCR results (N = 384) in a sample of adults living in Lebanon (n = 384) aged 18–75 years, November 2021–April 2022.
Table 2. s-25(OH)D levels, self-reported infection with SARS-CoV-2 and SARS-CoV-2 PCR results (N = 384) in a sample of adults living in Lebanon (n = 384) aged 18–75 years, November 2021–April 2022.
VariablesWomenMenMales vs. Females p-Value
PCR results % (n)PCR results % (n)
S-25(OH)D) cut-off (nmol/L)% (n),
  <30 nmol/L
  30–49.9 nmol/L
   ≥50 nmol/L 		37.5 (21)
21.4 (12)
41.1 (23)		30.8 (16)
48.1(25)
21.1 (11)		0.37
0.47
0.52
Have you been infected with COVID-19?
  Yes (confirmed by a doctor with a PCR test)
  Yes (due to symptoms)
  No (confirmed by a doctor with a PCR test)
  No (due to lack of symptoms)		25.0 (14)
8.9 (5)
46.4 (26)
19.6 (11)		26.9 (14)
3.8 (2)
53.8 (28)
15.4 (8)
Table 3. Results of multiple logistic regression with odds ratios (OR), 95% confidence intervals (CI) and p-values for SARS-CoV-2 positivity and vitamin D status as primary predictor and age, gender, education and BMI as potential confounders in a sample of adults living in Lebanon (n = 384) aged 18–75 years, November 2021–April 2022.
Table 3. Results of multiple logistic regression with odds ratios (OR), 95% confidence intervals (CI) and p-values for SARS-CoV-2 positivity and vitamin D status as primary predictor and age, gender, education and BMI as potential confounders in a sample of adults living in Lebanon (n = 384) aged 18–75 years, November 2021–April 2022.
Vitamin D Category (nmol/L)
Sufficiency *
(s-25(OH)D (≥50)
N = 143		Insufficiency #
(s-25(OH)D (30–49.99)
N = 126		Deficiency **
(s-25(OH)D (<29.99)
N = 115
COVID-19 positivity (%)23.8%29.4%32.2%
OR (95% CI), unadjusted
p-value		1.00 (Ref)1.3 (0.77–2.29)
0.30		1.5 (0.88–2.63)
0.13
OR (95% CI), adjusted †
p-value		1.00 (Ref)1.24 (0.71–2.19)
0.45		1.51 (0.87–2.64)
0.14
† adjusted for gender, age, BMI and education level; * (s-25(OH)D(≥50); # (s-25(OH)D (30–49.99); ** s-25(OH) D (<29.99).
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MDPI and ACS Style

Madar, A.A.; Al Lababidi, F.; Samia, F.; Meyer, H.E. Vitamin D Status and SARS-CoV-2 Positivity in Lebanon Among Adults: A Cross-Sectional Study in South Lebanon. COVID 2025, 5, 97. https://doi.org/10.3390/covid5070097

AMA Style

Madar AA, Al Lababidi F, Samia F, Meyer HE. Vitamin D Status and SARS-CoV-2 Positivity in Lebanon Among Adults: A Cross-Sectional Study in South Lebanon. COVID. 2025; 5(7):97. https://doi.org/10.3390/covid5070097

Chicago/Turabian Style

Madar, Ahmed A., Firass Al Lababidi, Filali Samia, and Haakon E. Meyer. 2025. "Vitamin D Status and SARS-CoV-2 Positivity in Lebanon Among Adults: A Cross-Sectional Study in South Lebanon" COVID 5, no. 7: 97. https://doi.org/10.3390/covid5070097

APA Style

Madar, A. A., Al Lababidi, F., Samia, F., & Meyer, H. E. (2025). Vitamin D Status and SARS-CoV-2 Positivity in Lebanon Among Adults: A Cross-Sectional Study in South Lebanon. COVID, 5(7), 97. https://doi.org/10.3390/covid5070097

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