Objectives:
There are large knowledge gaps regarding how transmission of 2019 novel coronavirus disease (COVID-19) occurred in different settings across the world. Therefore, this review article has been conducted.

Objectives:
Does L-arginine supplementation improve biomarkers (fasting blood sugar, insulin, HbA1c and HOMA-IR values) of glycemic control in adults?

Study design:
This review article included 12 randomised clinical trials (RCTs).

Objectives:
What are the reactogenicity, immunogenicity and efficacy across different vaccine platforms?

Study design:
This review article included 23 non-human primates studies and 32 human studies.
The mean age in human trials was 42.7 years.
The gender distribution in human vaccine groups was roughly equal.
Vaccine group ethnicity was skewed as follows: 72.8% of participants were White, 11.2% Hispanic, 7.2% Black/African American and 3.9% Asian.

Objectives:
Lifestyle interventions are an important and viable approach for preventing cognitive deficits. However, the results of studies on alcohol, coffee and tea consumption in relation to cognitive decline have been divergent, likely due to confounds from dose-response effects. Therefore, this review article (meta-analysis) has been conducted.

Objectives:
Do hospitalized non-intubated patients with COVID-19 benefit from treatment with anakinra?

Study design:
This review article included 9 trials with 1,119 COVID-19 patients. 
The bias risk with reference to the assessed parameters was high.

Results and conclusions:   

Objectives:
Does coenzyme Q10 supplementation improve oxidative stress variables?

Study design:
This review article included 17 RCTs with 972 participants.

Results and conclusions:

Objectives:
In Sub-Saharan Africa (SSA), where malaria transmission is stable, malaria infection in pregnancy adversely affects pregnant women, fetuses and newborns and is often asymptomatic. So far, a plethora of primary studies have been carried out on asymptomatic malaria infection in pregnant women in Sub-Saharan Africa. Nevertheless, no meta-analysis estimated the burden of asymptomatic malaria infection in pregnant women in Sub-Saharan Africa. Therefore, this review article (meta-analysis) has been conducted.  

Objectives:
Does IL-6 inhibitor tocilizumab (TCZ) reduce mortality among hospitalized COVID-19 patients?

Study design:
This review article included 8 RCTs, assessing 6,481 patients with mostly severe non-critical COVID-19 infection.

Results and conclusions:   
The investigators found treatment with IL-6 inhibitor tocilizumab (TCZ) was significantly associated with a reduction of 11% in all-cause 28-30-day mortality compared to placebo/control [RR = 0.89, 95% CI = 0.82 to 0.96].

Objectives:
Does intake of folic acid during pregnancy reduce risk of offspring's autism spectrum disorders?

Study design:
This review article included 10 studies with 23 sub-studies (9,795 autism spectrum disorders cases).

Results and conclusions:
The investigators found folic acid supplementation during early pregnancy significantly reduced risk of offspring's autism spectrum disorders with 43% [OR = 0.57, 95% CI = 0.41 to 0.78].

Objectives:
The outbreak of coronavirus disease 2019 (COVID-19) has been an almost global pandemic with significant public health impacts. The increasing prevalence of malignancy has become a leading cause of human mortality. However, conflicting findings have been published on the association between malignancy and COVID-19 severity. Therefore, this review article has been conducted.