Patients with multiple myeloma (MM) have a diminished immune response to coronavirus disease 2019 (COVID-19) vaccines. Risk factors for an impaired immune response are yet to be determined. We aimed to summarize the COVID-19 vaccine immunogenicity and to identify factors that influence the humoral immune response in patients with MM. Two reviewers independently conducted a literature search in MEDLINE, Embase, ISI Web of Science, Cochrane library, and Clinicaltrials.gov from existence until 24 May 24 2022. (PROSPERO: CRD42021277005). A total of 15 studies were included in the systematic review and 5 were included in the meta-analysis. The average rate (range) of positive functional T-lymphocyte response was 44.2% (34.2%-48.5%) after 2 doses of messenger RNA (mRNA) COVID-19 vaccines. The average antispike antibody response rates (range) were 42.7% (20.8%-88.5%) and 78.2% (55.8%-94.2%) after 1 and 2 doses of mRNA COVID-19 vaccines, respectively. The average neutralizing antibody response rates (range) were 25% (1 study) and 62.7% (53.3%-68.6%) after 1 and 2 doses of mRNA COVID-19 vaccines, respectively. Patients with high-risk cytogenetics or receiving anti-CD38 therapy were less likely to have a humoral immune response with pooled odds ratios of 0.36 (95% confidence interval [95% CI], 0.18, 0.69), I2 = 0% and 0.42 (95% CI, 0.22, 0.79), I2 = 14%, respectively. Patients who were not on active MM treatment were more likely to respond with pooled odds ratio of 2.42 (95% CI, 1.10, 5.33), I2 = 7%. Patients with MM had low rates of humoral and cellular immune responses to the mRNA COVID-19 vaccines. Further studies are needed to determine the optimal doses of vaccines and evaluate the use of monoclonal antibodies for pre-exposure prophylaxis in this population.

Coagulation activation has been reported in several cohorts of patients Coronavirus Disease 2019 (COVID-19). However, the true burden of systemic coagulopathy in COVID-19 remains unknown. In this systematic review and meta-analysis, we performed a literature search using PubMed, EMBASE, and Cochrane Database to identify studies that reported the prevalence of systemic coagulopathy using established criteria in patients with COVID-19. The primary outcome was the prevalence of systemic coagulopathy (disseminated intravascular coagulation [DIC] and/or sepsis-induced coagulopathy [SIC]). Pooled prevalences and 95% confidence intervals [CIs] were calculated using random-effects model. A total of 5 studies including 1210 patients with confirmed COVID-19 were included. The pooled prevalence of systemic coagulopathy was 7.1% (95%CI: 3.2%,15.3%, I² = 93%). The pooled prevalence of DIC (N = 721) and SIC (N = 639) were 4.3% (95%CI 1.7%, 10.4%, I² = 84%) and 16.2% (95%CI: 9.3%, 26.8%, I² = 74%), respectively. Only 2 studies reported the prevalence of elevated D-dimer levels with the pooled prevalence of 84.6% (95%CI: 52.0%,96.5%, I² = 94%). Average D-dimer and fibrinogen levels were remarkably increased, while platelet counts, PT, and aPTT ratios were minimally affected in COVID-19. The estimated prevalence of systemic coagulopathy in patients with COVID-19 was low despite D-dimer elevation in most patients. Relatively low systemic coagulopathy in COVID-19 may contribute to the high incidence of thrombosis rather than bleeding in patients with COVID-19.

Hypercoagulability in coronavirus disease 2019 (COVID-19) may aggravate disease severity during hospitalization but the reported survival benefits from anticoagulation (AC) vary among studies. We performed a literature research to estimate pooled odds ratios (ORs) of in-hospital mortality and major bleeding comparing among intermediate-to-therapeutic dose AC, prophylactic dose AC, and no AC. Until October 22, 2020, PubMed, EMBASE, and Cochrane Library Database were searched for studies reporting AC utilization and mortality in COVID-19. Studies with suspected risk of bias were excluded before the synthesis of pooled ORs with 95% confidence intervals (CIs) using random-effects models. Of 37 identified studies (N = 19,510), 17 (N = 17,833) were aggregated in the meta-analysis. The overall mortality rate was 23.1% (95% CI 18.7-28.2). The pooled odds of mortality comparing anticoagulated to non-anticoagulated patients were similar, but lower in prophylactic dose AC group (OR 0.83; 95% CI 0.73-0.95). Notably, intermediate-to-therapeutic dose AC increased mortality (OR 1.60; 95% CI 1.11-2.31) and major bleeding compared to prophylactic dose AC (OR 3.33; 95% CI 2.34-4.72). Our findings support the optimal efficacy and safety profiles of prophylactic dose AC in hospitalized COVID-19 patients.

Hemophilia is an inherited bleeding disorder caused by deficiency of a specific coagulation factor. Factor VIII deficiency is responsible for hemophilia A while factor IX deficiency is responsible for hemophilia B. As per the 2020 annual global survey by the World Federation of Hemophilia, only 1828 Thai hemophiliacs have been registered to the national healthcare system. The reason for the low number is the underdiagnosis which is a major concern in the real-world practice among Asian countries. In Thailand, most hemophiliacs are diagnosed by general practitioners, pediatricians or internists at rural hospitals and are referred to hemophilia specialists at the Hemophilia Treatment Centers (HTCs). Despite the challenges pertaining to infrastructure and cost of treatment, Thailand has progressed substantially in providing the required hemophilia care, as evidenced by an evolution in acquiring and sharing knowledge as well as collaborative efforts among multiple stakeholders over the past three decades. In this letter-to-the-editor, the authors have summarized the practices for and challenges faced with hemophilia management in Thailand.