Altered Influenza Vaccination Coverage and Related Factors in Pregnant Women in Korea from 2007 to 2019.

BACKGROUND: Pregnant women are at a high-risk of influenza infection. We have previously reported a low influenza vaccination coverage rate (4.0%) in Korea during the 2006-2007 influenza season. We conducted follow-up studies in 2011-2012 and 2018-2019 to observe changes in influenza vaccination coverage. METHODS: Women who delivered at Inha University Hospital (Incheon, Korea) in 2011-2012 and 2018-2019 were enrolled in the study. We surveyed the rate of influenza vaccination, perception scores, and related factors through telephonic interviews and compared the results from 2011-2012 and 2018-2019 with those from 2006-2007. RESULTS: The number of survey respondents was 227 in 2006-2007, 152 in 2011-2012, and 171 in 2018-2019. The rate of vaccination coverage increased from 4.0% in 2006-2007 to 42.0% in 2011-2012 and 59.3% in 2018-2019. Perception scores also increased progressively from 3.8 in 2006-2007 to 4.2 in 2011-2012 and 5.1 in 2018-2019. Physician recommendations for influenza vaccination also increased from 4.8% in 2006-2007 to 36.8% in 2011-2012 and 49.7% in 2018-2019. The most common reason for not getting vaccinated was the lack of awareness of influenza vaccination during pregnancy (36.9%). The perception scores and physician recommendation rates were significantly lower for unvaccinated women (3.87 and 8.4%, respectively) than for vaccinated women (5.14 and 69.1%, respectively). CONCLUSION: The influenza vaccination coverage rate in pregnant women has increased significantly since our study in 2006-2007. However, further improvement in the coverage rate is needed. There is a need for active and comprehensive publicity and education regarding this issue among physicians and pregnant women.

Splenic infarction and infectious diseases in Korea.

BACKGROUND: The spleen contains immune cells and exhibits a pattern of infarction different from other organs; as such, splenic infarction (SI) may provide important clues to infection. However, the nature of the relationship between SI and infectious disease(s) is not well understood. Accordingly, this retrospective study investigated the relationship between SI and infection. METHODS: Hospital records of patients with SI, who visited Inha University Hospital (Incheon, Republic of Korea) between January 2008 and December 2018, were reviewed. Patient data regarding clinical presentation, causative pathogens, risk factors, and radiological findings were collected and analyzed. RESULTS: Of 353 patients with SI, 101 with infectious conditions were enrolled in this study, and their data were analyzed to identify associations between SI and infection. Ten patients were diagnosed with infective endocarditis (IE), and 26 exhibited bacteremia without IE. Twenty-seven patients experienced systemic infection due to miscellaneous causes (negative result on conventional automated blood culture), including the following intracellular organisms: parasites (malaria [n = 12], babesiosis [n = 1]); bacteria (scrub typhus [n = 5]); viruses (Epstein-Barr [n = 1], cytomegalovirus [n = 1]); and unidentified pathogen[s] (n = 7). Splenomegaly was more common among patients with miscellaneous systemic infection; infarction involving other organs was rare. Thirty-eight patients had localized infections (e.g., respiratory, intra-abdominal, or skin and soft tissue infection), and most (35 of 38) had other risk factors for SI. CONCLUSIONS: In this study, various infectious conditions were found to be associated with SI, and intracellular organisms were the most common causative pathogens. Further studies are needed to examine other possible etiologies and the underlying pathophysiological mechanisms.

A case of Henoch-Schönlein purpura associated with scrub typhus.

BACKGROUND: Henoch-Schönlein purpura (HSP) may be caused by several allergens. However, to date, HSP caused by Orientia tsutsugamushi has not been reported. Here, we report an unusual rash with features of HSP caused by Orientia tsutsugamushi. CASE PRESENTATION: A man visited a tertiary hospital with bilateral symmetrical purpura and fever. He presented with an eschar in the left popliteal fossa and proteinuria. He was diagnosed with tsutsugamushi disease by indirect fluorescent antibody and positive polymerase chain reaction tests. Purpura biopsy demonstrated a feature of leukocytoclastic vasculitis and IgA deposition in dermal vessels, indicative of HSP. CONCLUSIONS: When examining patients with unique rashes, such as in this case, we suggest investigating out-door activities and evidence of mite bites. Furthermore, differential diagnosis of tsutsugamushi disease should be considered when necessary.

Convalescent Plasma Therapy in Coronavirus Disease 2019: a Case Report and Suggestions to Overcome Obstacles.

Coronavirus disease 2019 (COVID-19) is rapidly spreading around the world, causing much morbidity and mortality everywhere. However, effective treatments or vaccines are still not available. Although convalescent plasma (CP) therapy can be useful in the treatment of COVID-19, it has not been widely used in Korea because of the concerns about adverse effects and the difficulty in matching patients to donors. The use of ABO-incompatible plasma is not contraindicated in treatment, but can be hesitated due to the lack of experience of physicians. Here, we describe a 68-year old man with COVID-19 who was treated ABO-incompatible plasma therapy; additionally, we comment on the acute side effects associated with ABO mismatch transfusion. To overcome the obstacles of donor-recipient connections (schedule and distance), we propose the storage of frozen plasma, modification of the current Blood Management Law, and the establishment of a CP bank. We suggest that experience gained in CP therapy will be useful for not only the treatment of COVID-19, but also for coping with new emerging infectious diseases.

Geographic distribution of Tick-borne encephalitis virus complex.

A comprehensive understanding of the geographic distribution of the tick-borne encephalitis virus (TBEV) complex is necessary due to increasing transboundary movement and cross-reactivity of serological tests. This review was conducted to identify the geographic distribution of the TBEV complex, including TBE virus, Alkhurma haemorrhagic fever virus, Kyasanur forest disease virus, louping-ill virus, Omsk haemorrhagic fever virus, and Powassan virus. Published reports were identified using PubMed, EMBASE, and the Cochrane library. In addition to TBEV complex case-related studies, seroprevalence studies were also retrieved to assess the risk of TBEV complex infection. Among 1406 search results, 314 articles met the inclusion criteria. The following countries, which are known to TBEV epidemic region, had conducted national surveillance studies: Austria, China, Czech, Denmark, Estonia, Finland, Germany, Hungary, Italy, Latvia, Norway, Poland, Romania, Russia, Switzerland, Sweden, Slovenia, and Slovakia. There were also studies/reports on human TBEV infection from Belarus, Bulgaria, Croatia, France, Japan, Kyrgyzstan, Netherland, and Turkey. Seroprevalence studies were found in some areas far from the TBEV belt, specifically Malaysia, Comoros, Djibouti, and Kenya. Kyasanur forest disease virus was reported in southwestern India and Yunnan of China, the Powassan virus in the United States, Canada, and east Siberia, Alkhurma haemorrhagic fever virus in Saudi Arabia and east Egypt, and Louping-ill virus in the United Kingdom, Ireland, and east Siberia. In some areas, the distribution of the TBEV complex overlaps with that of other viruses, and caution is recommended during serologic diagnosis. The geographic distribution of the TBEV complex appears to be wide and overlap of the TBE virus complex with other viruses was observed in some areas. Knowledge of the geographical distribution of the TBEV complex could help avoid cross-reactivity during the serologic diagnosis of these viruses. Surveillance studies can implement effective control measures according to the distribution pattern of these viruses.

Actinomycotic osteomyelitis of a long bone in an immunocompetent adult: a case report and literature review.

BACKGROUND: Actinomycosis is a rare, chronic granulomatous disease caused by Gram-positive anaerobic bacteria that colonize the oral cavity. Cervicofacial actinomycosis is the most frequent clinical presentation of actinomycosis, but hematogenous osteomyelitis at distant sites can occur in rare instance in immunocompromised or pediatric patients, only a few cases have been reported in healthy patients. Here we described a new case of distal femur osteomyelitis caused by Actinomyces in an adult patient who was immunocompetent and had no predisposing factors. CASE PRESENTATION: A woman aged 52 years with no history of trauma presented with severe pain, swelling, and increased local heat in the proximal area of the right knee 3 weeks after she first noticed discomfort. Magnetic resonance imaging showed persistent osteomyelitis of the distal metaphysis and diaphysis of the femur with a multifocal intraosseous abscess pocket. An incision and drainage of the abscess were conducted. The tissue culture, fungus culture, acid fast bacillus (AFB) culture, AFB smear, and tuberculosis polymerase chain reaction test results were negative. A pathologic examination confirmed the presence of actinomycosis. The patient was successfully treated with intravenous penicillin G for 8 weeks followed by oral amoxicillin-clavulanate for 6 weeks with repeated surgical debridement and drainage. After a 5-year follow up, the patient had no signs of recurring infection or complications and she had full range of movement in the affected knee. CONCLUSIONS: Although rare, actinomycotic osteomyelitis can occur in healthy people. Furthermore, actinomycotic osteomyelitis is easily misdiagnosed as tuberculosis in areas with a high prevalence of tuberculosis. To detect and identify the bacteria accurately, pathologic examination should be performed as well as culture tests, because the probability for culture confirmation of actinomycosis is quite low. The initial treatment is vital to a successful outcome without ostectomy or amputation.

Determinants of Compliance of Travelers with Vaccination and Malaria Prophylaxis at a Travel Clinic.

BACKGROUND: Pre-travel medical consultation is essential to reduce health impairment during travel. Yellow fever vaccination (YFV) is mandatory to enter some endemic countries. In this study, we evaluated the factors that affect compliance with appropriate prevention of infectious diseases in travelers who visited clinic for YFV. METHODS: For this retrospective study, chart reviews for 658 patients who visited a travel clinic for YFV before travel were conducted. The period of this study was from January 2016 to September 2018. The associations between appropriate vaccination and factors such as travel duration, destination, time of visiting clinic before departure, and purpose of travel were analyzed. RESULTS: Among 658 patients who got YFV during the study period, 344 patients (52.3%) received additional vaccination or malaria prophylaxis following a physician's recommendation. Travelers who visited the clinic more than 21 days before departure were more compliant than those who visited 14 days or fewer before departure (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.23-2.93; P = 0.004). Travelers visiting Africa were more compliant than were those traveling to South and Central America (OR, 1.97; 95% CI, 1.34-2.90; P = 0.001). Travelers in age groups of 40-49 years and over 70 years were less compliant than the 18-29 years old population (OR, 0.51; 95% CI, 0.28-0.93; P = 0.027 and OR, 0.19; 95% CI, 0.04-0.84; P = 0.03, respectively). Also, those who traveled for tour or to visit friends or relatives were more compliant than those who departed for business (OR, 0.77; 95% CI, 1.03-3.56; P = 0.04). CONCLUSION: For appropriate vaccination, pre-travel consultation at least 3 weeks before departure is crucial. Travelers should be aware of required vaccination and malaria prophylaxis before visiting South and Central America and Asia. Plans to enhance compliance of the elderly and business travelers should be contrived.

Subcapsular Splenic Hemorrhage in Vivax Malaria.

In malaria, splenic rupture is a serious complication potentially leading to death. Subcapsular hemorrhage of spleen is thought to be an impending sign of splenic rupture; however, the characteristics of subcapsular hemorrhage are not well known. We report 3 cases of subcapsular hemorrhage of the spleen in vivax malaria, with varying degrees of severity. Case 1 showed subcapsular hemorrhage without splenic rupture, was treated by antimalarial drug without any procedure. The healing process of the patient's spleen was monitored through 6 computed tomography follow-up examinations, over 118 days. Case 2 presented subcapsular hemorrhage with splenic rupture, treated only with an antimalarial drug. Case 3 showed subcapsular hemorrhage with splenic rupture and hypotension, treated using splenic artery embolization. They all recovered from subcapsular hemorrhage without any other complications. These 3 cases reveal the process of subcapsular hemorrhage leading to rupture and a potentially fatal outcome. The treatment plan of subcapsular hemorrhage should be determined carefully considering the vital signs, changes in hemoglobin, and bleeding tendency.

Characterization of Clinical Isolates of Bartonella henselae Strains, South Korea.

Bartonella henselae, a gram-negative bacterium, is a common causative agent of zoonotic infections. We report 5 culture-proven cases of B. henselae infection in South Korea. By alignment of the 16S rRNA sequences and multilocus sequencing typing analysis, we identified all isolates as B. henselae Houston-1 strain, which belongs to sequence type 1.

Two Imported Cases of Babesiosis with Complication or Co-Infection with Lyme Disease in Republic of Korea.

Babesiosis, caused by Babesia microti and B. divergens, is transmitted by Ixodid ticks. Symptoms of babesiosis vary from a mild flu-like illness to acute, severe, and sometimes fatal and fulminant disease. In Korea, 7 imported babesiosis cases and 1 endemic case have been reported. We report 2 cases of severe babesiosis initially mistaken as malaria. The first patient was complicated by shock and splenic infarction, the other co-infected with Lyme disease. As the population traveling abroad increases every year, physicians should be aware of babesiosis which mimics malaria, co-infection with other diseases, and its complications.

Severe Plasmodium vivax infection in Korea.

BACKGROUND: Although severe malaria by Plasmodium vivax has been increasingly reported, there are marked variations in the type and rate of the complications by geographic area. This is possibly because of the presence of concurrent falciparum malaria or bacteraemia, and of differences in underlying immune status among the infected subjects. Furthermore, published studies on P. vivax in temperate regions are limited. The present study investigated severe vivax malaria in Korea, where only vivax malaria occurs. Hence, other compounding factors are rare. Additionally, most of the patients are possibly non-immune to this malarial disease. METHODS: Adults with vivax malaria observed in one 860-bed university hospital from January 2006 to December 2012 were retrospectively evaluated. Seventeen patients who had travelled overseas within 6 months before the presentation of malaria were excluded. Severe vivax malaria was diagnosed according to World Health Organization criteria. Other complications were also investigated. RESULTS: Two-hundred and ten patients were enrolled, of which 88 (41.9%) were treated as inpatients and the remainder as outpatients. Eleven patients were treated in an intensive care unit; among them, five patients received mechanical ventilation, and one needed extracorporeal membrane oxygenation therapy (ECMO) additionally. Severe vivax malaria was identified in 44 patients (21.0%), and the most common severe complication was pulmonary manifestation (40/188, 21.9%), which was followed by cerebral malaria (5/210, 2.4%), shock (4/210, 1.9%), spontaneous bleeding (3/210, 1.4%), metabolic acidosis (3/210, 3.5%) and acute kidney injury (2/210, 1.0%). Unusual complications, such as splenic infarction (ten patients) and retinal haemorrhage (two patients) were sometimes observed. There were no deaths, but the case involving ECMO was potentially fatal. CONCLUSIONS: Plasmodium vivax infection can be severe to be fatal and is frequently associated with various complications in non-immune adults. The frequency of each complication seems to differ from other countries. Hence, further investigation is needed to elucidate the causes and mechanisms responsible for these differences.

Identification of Outer Membrane Vesicles Derived from Orientia tsutsugamushi.

Orientia tsutsugamushi, a causative pathogen of Scrub typhus, is a gram-negative intracellular bacterium. Outer membrane vesicles (OMVs) are produced from the membrane of bacteria and play many roles related to the survival of the pathogen. However, there have been no reports confirming whether O. tsutsugamushi indeed produce OMVs. O. tsutsugamushi boryong was cultured in ECV-304 cells for the purification of OMVs. Western blot analysis and immunoenrichment using anti-O. tsutsugamushi monoclonal antibody and electron microscopy were employed for identification and characterization of OMVs. We confirm the presence of OMVs derived from O. tsutsugamushi, and also found that those OMVs contain a major surface antigen of 56-kDa protein and variant immunogenic antigens.

The effect of Epstein-Barr virus viremia on the progression to severe COVID-19.

ABSTRACT: Epstein-Barr virus (EBV) is frequently reactivated by coronavirus 2019 (COVID-19), and a high incidence of EBV viremia has been reported in patients with severe COVID-19. However, the impact of EBV viremia on progression to severe COVID-19 is unclear. Therefore, we conducted a study to evaluate the effect of EBV on COVID-19 progression.We investigated EBV viremia at the time of admission in COVID-19 patients hospitalized between February 1, 2020, and April 11, 2021. A cross-sectional study was performed to compare the severity of COVID-19 according to the presence or absence of EBV viremia. However, since it is difficult to analyze the influence of EBV viremia on COVID-19 progression with cross-sectional studies, a retrospective cohort study, limited to patients with mild COVID-19, was additionally conducted to observe progression to severe COVID-19 according to the presence or absence of EBV viremia.Two hundred sixty-nine COVID-19 patients were tested for EBV viremia. In a cross-sectional study that included patients with both mild and severe COVID-19, the EBV viremia group had more severe pneumonia than the EBV-negative group. However, in the cohort study limited to mild cases (N = 213), EBV viremia was not associated with COVID-19 progression.COVID-19 severity may affect EBV viremia; however, there was no evidence that EBV viremia was a factor in exacerbating pneumonia in patients with mild COVID-19.

Effect of a serum lactate monitoring recommendation policy on patients treated with linezolid.

ABSTRACT: Lactic acidosis is one of the most fatal adverse effects of linezolid, an antibiotic used to treat serious infections caused by antibiotic-resistant bacteria. However, the measures to prevent lactic acidosis have not been well established.We performed a retrospective study to analyze the impact of applying a serum lactate monitoring recommendation policy in patients treated with linezolid.Since September 2011, we have recommended inpatient monitoring of serum lactate levels in patients treated with linezolid at our hospital. Patients were divided into two groups according to whether they were seen during the non-recommendation or recommendation periods. The frequency of serum lactate monitoring, linezolid-induced lactatemia, lactic acidosis, critical illness, and death were compared between the two periods.After September 2011, adherence to the recommendation to monitor serum lactate increased from 6.1% to 60.1%. No difference was observed in the incidence of linezolid-induced lactatemia and lactic acidosis between the two periods. However, there was a significant difference in the incidence of linezolid-induced critical illness between the non-recommendation and recommendation periods (3 vs 0 cases, P = .044).In patients treated with linezolid, serum lactate monitoring led to early detection of lactatemia, thus enabling rapid rescue. We recommend regular monitoring of serum lactate in all patients treated with linezolid.

Current Status and a Perspective of Mosquito-Borne Diseases in the Republic of Korea.

Background: Mosquito-borne diseases in the Republic of Korea have a unique epidemiology due to the rapid improvement in hygiene and economic status, occurrence of four distinct seasons, and separation from North Korea owing to the political situation. Therefore, we aimed to analyze and review the epidemiology of mosquito-borne diseases in Korea. Methods: The incidence and geographical distribution of malaria, Japanese encephalitis (JE), Zika virus infection, chikungunya fever, and dengue fever were investigated using data from the Korean Centers for Disease Control and Prevention. Lymphatic filariasis and West Nile fever, which have rarely been reported in Korea, have also been discussed in this literature review. Results and Conclusions: Malaria disappeared from Korea in 1979, but since its re-emergence in 1993 there has been constant occurrence with local transmission. In Korea, vivax malaria is the only prevailing disease, and the clinically problematic chloroquine resistance has not been reported. The incidence of JE has greatly reduced since the introduction of the national vaccination program for children in 1985. However, the incidence of JE has been increasing recently, especially in adults >40 years of age. Filariasis, which was previously endemic to Jeju Island and the southern coastal area, has not been reported since 2002. Although there are numerous imported cases with increasing overseas travel, there are still no indigenous cases of Zika, chikungunya, and dengue fever reported in Korea. The West Nile virus was isolated from migratory birds, but there has been only one imported human case to date.

Percutaneous endoscopic gastrostomy feeding effects in patients with neurogenic dysphagia and recurrent pneumonia.

BACKGROUND: Percutaneous endoscopic gastrostomy (PEG) feeding provides enteral nutrition to patients with neurological dysphagia. However, the conditions in which PEG should be applied to prevent pneumonia remain unclear. We aimed to evaluate the effect of PEG for patients with neurological dysphagia in preventing pneumonia. METHODS: We undertook a retrospective data review of 232 patients with neurological dysphagia who had undergone PEG from January 2008 to December 2018 at Inha University Hospital, in Incheon, Korea. We excluded patients who had not been followed up 6 months pre- and post-PEG feeding. In total, our study comprised 42 patients. We compared pneumonia episodes and incidence pre- and post-PEG. RESULTS: During the median post-PEG follow-up period, the 6-month pneumonia incidence among patients who had undergone PEG had decreased [median 0.3 (interquartile range (IQR) 0.0-0.7) versus 0.1 (IQR 0.1-0.3) episodes, p = 0.04]. In a multiple mixed model, PEG did not decrease the incidence of pneumonia (p = 0.76). However, the association between PEG and the incidence of pneumonia differed significantly depending on the presence or absence of recurrent pneumonia (p < 0.001). CONCLUSIONS: PEG could effectively reduce the incidence of pneumonia in patients with neurogenic dysphagia, especially in those who had experienced recurrent pneumonia.The reviews of this paper are available via the supplemental material section.

Medical management of septic arthritis of sternoclavicular joint: A case report.

RATIONALE: Sternoclavicular joint septic arthritis is an unusual disease in healthy adults, and Staphylococcus aureus is the most common causative pathogen. The current treatment of choice is surgery with sternoclavicular joint resection and pectoralis flap closure, especially when the disease is complicated by osteomyelitis and abscess. PATIENT CONCERNS: Here, we report a 76-year-old woman without risk factors who visited our hospital for pain and redness, swelling on the left anterior chest wall. DIAGNOSIS: Magnetic resonance imaging showed infectious arthritis in the left SCJ, with multiple abscess pockets at the subcutaneous layer of anterior chest wall communicating with the joint cavity. Streptococcus agalactiae was isolated from blood culture. INTERVENTION: She was treated with 6 weeks of antibiotic therapy. OUTCOMES: After antibiotic treatment, she was successfully treated without recurrence. LESSONS: Besides surgery, medical treatment should also be considered for sternoclavicular joint septic arthritis, depending on patient status and the causative pathogen. Physicians should be aware of this rare disease to facilitate its prompt diagnosis and management.

Antinuclear antibodies in infectious diseases.

Introduction: Antinuclear antibody (ANA) tests are widely used for the diagnosis of autoimmune diseases, but ANAs are also commonly found in patients with various infections. This retrospective study aimed to investigate the relationship between infections and ANA status.Methods: Patients that visited the Department of Infectious Diseases at Inha University Hospital between January 2007 and July 2018 were investigated. We analysed their ANA test results and reviewed rheumatic and infectious diagnoses of patients with positive ANA findings.Results: Of the 9,320 patients during the study period, 1,111 underwent ANA testing and 110 tested positive. Seven of the 110 patients were previously diagnosed with ANA-positive disease, and 21 were diagnosed with autoimmune disease during the present study. Of the remaining 82 patients, 43 were confirmed with infectious disease. The most common pathogen was Mycobacterium tuberculosis (n = 10), followed by Treponema pallidum (n = 5), Orientia tsutsugamushi (n = 5), Escherichia coli (n = 5), Bartonella henselae (n = 3), and human immunodeficiency virus (n = 3). Of the 39 patients without a confirmed pathogen, 7 were seropositive for O. tsutsugamushi, B. henselae, or Rickettsia spp. Patients were observed at an average of 24 weeks in our hospital. One patient developed systemic lupus erythematosus after being diagnosed with Epstein-Barr virus-induced infectious mononucleosis, and another patient developed adult-onset Still's disease after being diagnosed with scrub typhus.Conclusion: This study showed that various relationships exist between infections and rheumatic diseases. In particular, several patients with a positive ANA test result were found to have intracellular infections such as mycobacterial infections, syphilis, or scrub typhus.

Nutritional status of patients with COVID-19.

The relationship between immunity and nutrition is well known and its role in coronavirus disease 2019 (COVID-19) is also being paid great attention. However, the nutritional status of COVID-19 patients is unknown. Vitamin B1, B6, B12, vitamin D (25-hydroxyvitamin D), folate, selenium, and zinc levels were measured in 50 hospitalized patients with COVID-19. Overall, 76% of the patients were vitamin D deficient and 42% were selenium deficient. No significant increase in the incidence of deficiency was found for vitamins B1, B6, and B12, folate, and zinc in patients with COVID-19. The COVID-19 group showed significantly lower vitamin D values than the healthy control group (150 people, matched by age/sex). Severe vitamin D deficiency (based on a cut-off of ≤10 ng/dl) was found in 24.0% of the patients in the COVID-19 group and 7.3% in the control group. Among 12 patients with respiratory distress, 11 (91.7%) were deficient in at least one nutrient. However, patients without respiratory distress showed a deficiency in 30/38 cases (78.9%; p = 0.425). These results suggest that a deficiency of vitamin D or selenium may decrease the immune defenses against COVID-19 and cause progression to severe disease. However, more precise and large-scale studies are needed.

Systematic review and meta-analysis of immune response of double dose of hepatitis B vaccination in HIV-infected patients.

INTRODUCTION: The prevalence of co-infection of hepatitis B virus (HBV) and human immunodeficiency virus (HIV) is high and increases risk of hepatitis B chronicity and mortality. Despite guidelines for HIV-infected patients to be immunized against HBV, the immunogenicity of the HBV vaccination in HIV-infected patients is lower than that in the HIV-seronegative population. METHOD: In this study, we performed a systematic review of the literature and meta-analysis of randomized clinical trials to investigate the response rate to an increased dose of HBV vaccination in HIV-infected patients. A fixed-effects model, with heterogeneity and sensitivity analyses, was used. We identified nine studies involving 970 HIV-positive vaccine recipients. RESULTS: The study results were divided into two groups, depending on the time when antibody against hepatitis surface antigen was measured. Results showed a significant increase in response rates among patients who received a double dose of the vaccine versus the standard dose in both subgroups; the pooled odds ratio (OR) was 1.76 (95% confidence interval [CI]: 1.36-2.29) and 2.28 (95% CI: 1.73-3.01) for the rate that was measured 4-6 weeks and >12 months after completion of vaccination, respectively. The total OR was 1.99 (95% CI: 1.64-2.41). No heterogeneity was found. DISCUSSION: Our meta-analysis shows that a double dose of the HBV vaccine may significantly improve the immune response in HIV-infected patients. Higher immunogenicity was observed, when it was measured 4-6 weeks and >12 months after completion of the vaccination.