It remains unclear how effective COVID-19 vaccinations will be in patients with weakened immunity due to diseases, transplantation, and dialysis. We conducted a systematic review comparing the efficacy of COVID-19 vaccination in patients with solid tumor, hematologic malignancy, autoimmune disease, inflammatory bowel disease, and patients who received transplantation or dialysis. A literature search was conducted twice using the Medline/PubMed database. As a result, 21 papers were included in the review, and seropositivity rate was summarized by specific type of disease, transplantation, and dialysis. When different papers studied the same type of patient group, a study with a higher number of participants was selected.Most of the solid tumor patients showed a seropositivity rate of more than 80% after the second inoculation, but a low seropositivity was found in certain tumors such as breast cancer. Research in patients with certain types of hematological malignancy and autoimmune diseases has also reported low seropositivity, and this

As coronavirus variants are constantly occurring, we tried to understand more about the omicron and delta variants that have hit the world. We provided dynamic information on the case fatality rate (CFR) of the Omicron variant over time and to compare it with that of the Delta variant through meta‐analysis. Twenty‐four countries were selected by submission counts, submission dates, and confirmed cases. We defined the Delta or the Omicron epidemic period for individual countries as when each variant is over 90%. We further analyzed the Omicron period by dividing it into the initial plateau, increasing, and decreasing phases according to the number of newly confirmed daily cases. Finally, the meta‐analysis examined the summary and between‐study heterogeneity. The CFR of COVID‐19 during the Omicron epidemic was lower than that during the Delta epidemic (odds ratio [OR]: 0.252, 95% confidence interval [CI] 0.205−0.309). The CFR of COVID‐19 during the initial plateau phase of Omicron was higher than during other phases. (OR: 1.962, 95% CI 1.607−2.397). The CFR of COVID‐19 during the increasing phase was lower than during the decreasing phases (OR: 0.412, 95% CI 0.342–0.498). The Omicron variant had lower CFR compared to the Delta variant, and the initial plateau phase had higher CFR compared to the noninitial phases. These results can help establish global health policies for COVID‐19 in the future.

Nonalcoholic fatty liver disease (NAFLD) is a liver disease that affects approximately 25% of the world's population, and various treatments have been applied for NAFLD patients. We compared the effectiveness of each intervention conducted to treat NAFLD by evaluating meta-analyses of pharmacological interventions and lifestyle modification including diet and exercise. We searched Pubmed/Medline, Embase, and Cochrane Library and included meta-analyses of randomized controlled trials investigating the effects of pharmacological intervention and lifestyle modification on NAFLD.