Qdenga® - A promising dengue fever vaccine; can it be recommended to non-immune travelers?

Qdenga® has been approved by the European Medicines Agency (EMA) for individuals > 4 years of age and for use according to national recommendations. The vaccine shows high efficacy against virologically confirmed dengue and severe dengue in clinical studies on 4-16-year old's living in endemic areas. For individuals 16-60 years old only serological data exists and there is no data for individuals > 60 years. Its use as a travel vaccine is still unclear. We present the studies behind the approval and the recommendations for travelers as issued by the Swedish Society for Infectious Diseases Physicians.

Recent MMR vaccination in health care workers and Covid-19: A test negative case-control study.

BACKGROUND: It has been hypothesised that the measles-mumps-rubella (MMR) vaccine may afford cross-protection against SARS-CoV-2 which may contribute to the wide variability in disease severity of Covid-19. METHODS: We employed a test negative case-control study, utilising a recent measles outbreak during which many healthcare workers received the MMR vaccine, to investigate the potential protective effect of MMR against SARS-CoV-2 in 5905 subjects (n = 805 males, n = 5100 females). RESULTS: The odds ratio for testing positive for SARS-CoV-2, in recently MMR-vaccinated compared to not recently MMR-vaccinated individuals was 0.91 (95% CI 0.76, 1.09). An interaction analysis showed a significant interaction for sex. After sex-stratification, the odds ratio for testing positive for males was 0.43 (95% CI 0.24, 0.79, P = 0.006), and 1.01 (95% CI 0.83, 1.22, P = 0.92) for females. CONCLUSION: Our results indicate that there may be a protective effect of the MMR vaccine against SARS-CoV-2 in males but not females.

Long-lasting chronic high load carriage of Epstein-Barr virus is more common in young pediatric renal transplant recipients.

BACKGROUND: Epstein-Barr virus (EBV) infections can induce post-transplant lymphoproliferative disorder (PTLD). A chronic high load (CHL), as indicated by long-term high EBV DNA levels after transplantation, has been associated with an enhanced risk of PTLD. We aimed to evaluate incidence, time of occurrence, risk factors, and outcome of EBV CHL carrier state after pediatric renal transplantation. METHODS: A retrospective study of 58 children aged 1-17 years (median 10), who underwent renal transplantation between January 2004 and June 2017 at a single medical center. EBV IgG antibodies in serum were analyzed before and yearly after transplantation. EBV DNA in whole blood were analyzed weekly for the first 3 months post-transplant, monthly up to 1 year and then at least once yearly. CHL was defined as EBV DNA ≥ 4.2 log10 Geq/ml in > 50% of the samples during ≥ 6 months. RESULTS: At transplantation, 31 (53%) patients lacked EBV IgG and 25 (81%) of them developed primary EBV infection post-transplant. Of the 27 seropositive patients, 20 (74%) experienced reactivation of EBV. Altogether, 14 (24%) children developed CHL, starting at a median of 69 days post-transplant and lasting for a median time of 2.3 years (range 0.5-6.5), despite reduction of immunosuppression. Patients with CHL were younger and 11/14 were EBV seronegative at transplantation. No child developed PTLD during median clinical follow-up of 7.8 years (range 0.7-13). CONCLUSIONS: CHL was frequent, long lasting, and occurred mainly in young transplant recipients. The absence of PTLD suggests that monitoring of EBV DNA to guide immunosuppression was effective.

Long-term study showed that vaccination protected paediatric renal transplant recipients from life-threatening varicella zoster virus.

AIM: Renal transplant patients are particularly susceptible to highly contagious diseases due to their reduced immunity. We studied transplant recipients to gauge their varicella zoster virus (VZV) serology status over time and the outcome of any VZV infections. METHOD: This retrospective study comprised 85 children who underwent renal transplants in Gothenburg, Sweden, from 1986 to 2014, at a mean age of eight (1-18) years. The children's medical records were reviewed and 47 had the VZV infection pre-transplant and 38 had been vaccinated pre-transplant. Clinical outcomes were available for 85 children and serology results for 72. RESULTS: At transplantation, the VZV seropositivity rate was 50% in the vaccination group and 94% in the infection group and the antibody titres were significantly lower in the vaccination group (p = 0.031). During the median follow-up period of five years post-transplant, 28% of the vaccinated children and 97% of the infection group remained seropositive and the varicella infection affected eight children: one in the infection group and seven in the vaccination group. The herpes zoster was observed in two children in the infection group. CONCLUSION: This study demonstrated that VZV vaccination protected from symptomatic infections to a lesser extent than natural infection, but provided effective protection from life-threatening disease.

Human herpesvirus type 6 DNAemia and infection following allogeneic stem cell transplantation with a focus on long-term outcome.

Cases of human herpesvirus type 6 (HHV-6) infection and disease were retrospectively analysed in a cohort of 97 allogeneic haematopoietic stem cell transplantation (allo-SCT) patients in Gothenburg, Sweden (1997-2001). Altogether 54 of 97 (56%) patients were tested for HHV-6. HHV-6 DNAemia was detected in 15 of the tested patients at a median of 76 (range 24-387) days after SCT. Nine of these patients were treated against HHV-6 infection and disease for a total of 11 treatment episodes. The morbidity associated with HHV-6 DNAemia following allo-SCT was in most cases moderate. The overall 1-y survival among the patients with HHV-6 DNAemia was 11/15 (73%) and the 5-y survival was 10/15 (67%), which was not significantly different from the whole cohort.

Cytomegalovirus DNAemia and treatment following allogeneic stem cell transplantation with a focus on long-term outcome.

Cytomegalovirus (CMV) is an important factor for morbidity and long-term outcome after allogeneic haematopoetic stem cell transplantation (allo-SCT). Cases of proven and probable CMV infection and disease among 97 allo-SCT recipients in Gothenburg, Sweden, 1997-2001, were analysed. CMV DNAemia was detected in 60 patients at a median of 30 days after SCT. Four patients (4%) had CMV disease; 2 had proven and 2 had probable CMV disease. Of these 4 patients, 1 died of CMV disease. In 1 additional patient, CMV was considered to have contributed to the patient's death. Fifty patients (51%) were treated in a total of 93 treatment episodes. The overall 1-y survival was 75% and the 5-y survival 55%. Patients with diagnosed CMV DNAemia had improved survival. No significant differences in survival rates were seen between the donor/recipient serological groups. An increased risk of CMV DNAemia was seen after SCT with a seronegative donor to a seropositive recipient. CMV disease with debut more than 110 days after transplantation was related to steroid treatment for graft-versus-host disease. The morbidity related to CMV disease following allo-SCT was low over the past 10 y, probably due to CMV surveillance and early treatment.

Immunoglobulin deposits in liver tissue from infants with biliary atresia and the correlation to cytomegalovirus infection.

PURPOSE: The aim of this report was to study the amount and distribution of immunoglobulin deposits in liver biopsies from infants with biliary atresia (BA) and correlate the results to the cytomegalovirus (CMV) infection status. METHODS: Stored liver biopsies from 18 patients with BA and from 6 control patients without liver disease were immunohistochemically stained to detect IgG and IgM deposits. The intensity of the immunoglobulin staining was evaluated by a semiquantitative scoring scale. Ongoing CMV infection was defined as the detection of CMV-IgM in serum and/or the isolation of CMV in the urine and was noted in 9 of the patients with BA. RESULTS: When analyzing the immunoglobulin deposits on the hepatocellular canalicular membrane the intensity score for IgM deposits was significantly higher in biopsies from patients with BA infected with CMV than in those without. No canalicular staining was detected in control biopsies. CONCLUSIONS: The results support the possibility that immunologic mechanisms are of importance in the pathogenesis of BA and that a CMV infection may trigger such mechanisms.