Objectives:
Interleukin-6 (IL-6) is produced by and impacts different cell types in human. IL-6 is associated with different diseases and viral infections including COVID-19. However, no normal values were reported for IL-6 in the blood of healthy individuals. Therefore, this review article has been conducted.

What are the normal values for IL-6 in the blood of healthy individuals?  

Study design:
This review article included 57 studies which included 3,166 values for IL-6.

Objectives:
What is the diagnostic test accuracy (DTA) of nucleic acid-amplification tests (NAAT) for the diagnosis of coronavirus infections?

Study design:
This review article included 51 studies, of which 22 including 10,181 persons before COVID-19 and 29 including 8,742 persons diagnosing SARS-CoV-2.

Results and conclusions:   
The investigators found the overall summary sensitivity was 89.1% [95% CR = 84.0% to 92.7%] and the specificity was 98.9% [95% CR = 98.0% to 99.4%].

Objectives:
There is some inconclusive evidence for the role of fish consumption in susceptibility to multiple sclerosis (MS). Therefore, this review article has been conducted.

Does fish consumption reduce multiple sclerosis (MS)?

Objectives:
There is still limited evidence regarding the influence of vitamin D in people with COVID-19. Therefore, this review article has been conducted.

Does vitamin D deficiency increase risk of COVID-19 infections?

Study design:
This review article included 27 articles.

Results and conclusions:   
The investigators found vitamin D deficiency was not associated with a higher chance of infection by COVID-19 [OR = 1.35, 95% CI = 0.80 to 1.88].  

Objectives:
Soy products contain several compounds with anti-inflammatory properties like genistein and daidzein which reported to act through different pathways. However, there are inconsistent results and lack of any comprehensive review regarding randomized controlled trials which assess the effect of soy products on inflammatory markers. Therefore, this review article has been conducted.

Does soy product supplementation reduce levels of inflammatory markers, like CRP, IL-6?

Objectives:
What is the association between meteorological factors (temperature, relative humidity, wind speed and UV radiation) and transmission capacity of COVID-19?

Study design:
This review article included daily numbers of COVID-19 cases in 202 locations in 8 countries.

Results and conclusions:   
The investigators found temperature did not exhibit significant association with R0 of COVID-19 [meta p = 0.446].

Objectives:
Dietary sodium intake has received considerable attention as a potential risk factor of cardiovascular disease. However, evidence on the dose-response association between dietary sodium intake and cardiovascular disease risk is unclear. Therefore, this review article has been conducted.

Objectives:
The association between vitamin C intake and breast cancer is unclear. Therefore, this review article (meta-analysis) has been conducted.

Does a higher vitamin C intake reduce risk of breast cancer incidence, mortality and recurrence?

Study design:
This review article included 24 cohort studies and 30 case-control studies.

Objectives:
Africa still bears the largest burden of malaria as the majority of infections in the continent are caused by P. falciparum. Artemether-lumefantrine (AL, Coartem®) is the most widely used artemisinin-based combination therapy (ACT), for treating uncomplicated falciparum malaria globally. However, the development of resistance to antimalarial drugs is a major challenge for malaria control. Therefore, this review article has been conducted.

Objectives:
A higher body mass index (BMI) has become acknowledged as one of the important risk factors for developing critical condition in coronavirus disease 2019 (COVID-19). In addition to BMI, body composition, particularly visceral adiposity, might be an even more accurate measure to stratify patients. Therefore, this review article has been conducted.

Is abdominal adiposity a risk factor for COVID-19 infections?

Study design:
This review article included studies published until 17th November 2020.