Objectives:
To compare the immunogenicity and safety of the influenza vaccine at reduced or full intradermal doses with full intramuscular doses to inform policy design in the event of vaccine shortages.

Study design:
This review article included a total of 29 RCTs with 13,759 participants and 1 cohort study with 164,021 participants.
Approximately half of the studies (14 studies) involved only participants aged 60 years or older or reported data for participants aged 60 years or older.

Objectives:
Does a treatment with convalescent plasma decrease all-cause mortality risk in COVID-19 patients?

Study design:
This review article included 4 peer-reviewed RCTs with a total of 1,060 COVID-19 patients and 6 other publicly available RCTs with 10,722 COVID-19 patients.

The mean age of patients was younger than 70 years and they were typically male (≤80%).

The certainty of the evidence was low to moderate for all-cause mortality and low for other outcomes.

Objectives:
Does a low-carbohydrate diet (LCD) causally increase adiponectin concentration in adults?

Study design:
This review article included 11 RCTs with 534 participants in low-carbohydrate diet group and 513 participants in control group (group without a low-carbohydrate diet).
Proportion of carbohydrate from calorie was from 4 to 34% (4-34 En%).
Time of the follow-up varied between studies and ranged from 6 to 152 weeks.

Objectives:
Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus. Although general and local public health report deathly cases, case fatality rates are still largely unknown. Therefore, this review article has been conducted.

Objectives:
Does citrus dietary intake reduce the risk of lung cancer?

Study design:
This review article included 21 observational studies.

Results and conclusions:
The investigators found pooled analyses showed that those with the highest citrus fruit dietary intake compared to the lowest intake had a 9% reduction in lung cancer risk [OR = 0.91, 95% CI = 0.84 to 0.98].

Objectives:
While immunosuppression poses a theoretical increase in the risk of COVID-19, the nature of this relationship is yet to be ascertained. Therefore, this review article has been conducted.

Objectives:
Few observational studies have shown a beneficial effect of dipeptidyl peptidase-4 inhibitors (DPP4i) in patients with coronavirus disease 2019 (COVID-19), although results are not consistent. Therefore, this review article has been conducted.

Does use of DPP4i reduce COVID-19 mortality among patients with diabetes mellitus (DM)?

Study design:
This review article included 9 observational studies of high quality pooling data retrieved from 7,008 COVID-19 patients with diabetes mellitus (DM).

Objectives:
Coronavirus disease 2019 (COVID-19) has been reported to cause worse outcomes in patients with underlying cardiovascular disease, especially in patients with acute cardiac injury, which is determined by elevated levels of high-sensitivity troponin. There is a paucity of data on the impact of congestive heart failure (CHF) on outcomes in COVID-19 patients. Therefore, this review article has been conducted.

What is the impact of congestive heart failure (CHF) on outcomes in COVID-19 patients?

Objectives:
Recent systematic reviews and meta-analyses of randomized, double-blind, placebo-controlled trials (double-blind, placebo-controlled RCTs) have reported controversial findings regarding the associations between calcium supplements on the risk of cardiovascular disease (CVD). Therefore, this review article has been conducted.