Activation and Kinetics of Circulating T Follicular Helper Cells, Specific Plasmablast Response, and Development of Neutralizing Antibodies following Yellow Fever Virus Vaccination.

A single dose of the replication-competent, live-attenuated yellow fever virus (YFV) 17D vaccine provides lifelong immunity against human YFV infection. The magnitude, kinetics, and specificity of B cell responses to YFV 17D are relatively less understood than T cell responses. In this clinical study, we focused on early immune events critical for the development of humoral immunity to YFV 17D vaccination in 24 study subjects. More specifically, we studied the dynamics of several immune cell populations over time and the development of neutralizing Abs. At 7 d following vaccination, YFV RNA in serum as well as several antiviral proteins were detected as a sign of YFV 17D replication. Activation of Th1-polarized circulating T follicular helper cells followed germinal center activity, the latter assessed by the surrogate marker CXCL13 in serum. This coincided with a plasmablast expansion peaking at day 14 before returning to baseline levels at day 28. FluoroSpot-based analysis confirmed that plasmablasts were specific to the YFV-E protein. The frequencies of plasmablasts correlated with the magnitude of neutralizing Ab titers measured at day 90, suggesting that this transient B cell subset could be used as an early marker of induction of protective immunity. Additionally, YFV-specific memory B cells were readily detectable at 28 and 90 d following vaccination, and all study subjects tested developed protective neutralizing Ab titers. Taken together, these studies provide insights into key immune events leading to human B cell immunity following vaccination with the YFV 17D vaccine.

The Adjuvanted Recombinant Zoster Vaccine Confers Long-Term Protection Against Herpes Zoster: Interim Results of an Extension Study of the Pivotal Phase 3 Clinical Trials ZOE-50 and ZOE-70.

BACKGROUND: This ongoing follow-up study evaluated the persistence of efficacy and immune responses for 6 additional years in adults vaccinated with the glycoprotein E (gE)-based adjuvanted recombinant zoster vaccine (RZV) at age ≥50 years in 2 pivotal efficacy trials (ZOE-50 and ZOE-70). The present interim analysis was performed after ≥2 additional years of follow-up (between 5.1 and 7.1 years [mean] post-vaccination) and includes partial data for year (Y) 8 post-vaccination. METHODS: Annual assessments were performed for efficacy against herpes zoster (HZ) from Y6 post-vaccination and for anti-gE antibody concentrations and gE-specific CD4[2+] T-cell (expressing ≥2 of 4 assessed activation markers) frequencies from Y5 post-vaccination. RESULTS: Of 7413 participants enrolled for the long-term efficacy assessment, 7277 (mean age at vaccination, 67.2 years), 813, and 108 were included in the cohorts evaluating efficacy, humoral immune responses, and cell-mediated immune responses, respectively. Efficacy of RZV against HZ through this interim analysis was 84.0% (95% confidence interval [CI], 75.9-89.8) from the start of this follow-up study and 90.9% (95% CI, 88.2-93.2) from vaccination in ZOE-50/70. Annual vaccine efficacy estimates were >84% for each year since vaccination and remained stable through this interim analysis. Anti-gE antibody geometric mean concentrations and median frequencies of gE-specific CD4[2+] T cells reached a plateau at approximately 6-fold above pre-vaccination levels. CONCLUSIONS: Efficacy against HZ and immune responses to RZV remained high, suggesting that the clinical benefit of RZV in older adults is sustained for at least 7 years post-vaccination. Clinical Trials Registration. NCT02723773.

Chloroquine-susceptible and -resistant Plasmodium falciparum strains survive high chloroquine concentrations by becoming dormant but are eliminated by prolonged exposure.

BACKGROUND: Plasmodium falciparum strains that are resistant to standard-dose chloroquine can be treated by higher chloroquine concentrations maintained for a longer time in vivo. OBJECTIVES: To determine the relative importance of chloroquine concentrations versus exposure time for elimination of chloroquine-susceptible and -resistant P. falciparum in vitro. METHODS: Chloroquine-susceptible (3D7) and -resistant (FCR3) strains were exposed in vitro to 1, 2, 4, 8, 16 or 32 times their respective 90% inhibitory chloroquine concentrations for 3, 5, 7 or 14 days and then followed until recrudescence, or not, by 42 days after the end of exposure. RESULTS: Exposure to chloroquine appeared to eliminate susceptible and resistant parasites, leaving small pyknotic apparently dead parasites. Chloroquine-susceptible and -resistant parasites recrudesced after 3 and 5 days of chloroquine exposure. Recrudescence occurred in one out of four 7 day exposure series but not after 14 days exposure. The median time to recrudescence was 13 to 28 days with a range of 8 to 41 days after the end of exposure. Time to recrudescence after the end of exposure increased with duration of exposure for susceptible and resistant strains (P < 0.001). Time to recrudescence did not correlate with concentrations greater than 1× IC90. CONCLUSIONS: Chloroquine-susceptible and -resistant P. falciparum probably become dormant. Elimination of dormant parasites is primarily dependent upon the duration of chloroquine exposure. Exposure to effective drug concentrations for 7 days eliminates most parasites in vitro. The results support in vivo data indicating that elimination of chloroquine-resistant P. falciparum correlates with Day 7 chloroquine concentrations.

Magnitude and Functional Profile of the Human CD4+ T Cell Response throughout Primary Immunization with Tick-Borne Encephalitis Virus Vaccine.

Tick-borne encephalitis (TBE) is a viral infection of the CNS caused by TBE virus. With no specific treatment available, the only protection is a formalin-inactivated whole virus vaccine. Primary immunization with European TBE vaccines, as recommended by the manufacturers, consists of three vaccine doses administered within a 1-y period. Protection from vaccination is believed to be mediated by Abs, yet T cells may also have a protective role. We set out to characterize the human CD4+ T cell response throughout primary TBE immunization. The responses were evaluated before vaccination and 1 mo after each vaccine dose. A heterogeneous magnitude of CD4+ T cell-mediated memory responses was observed in regard to lymphoblast expansion and cytokine production (IFN-γ, IL-2, and TNF), with the highest median magnitude detected after the second dose of vaccine. Stimulation with an overlapping peptide library based on structural TBE virus proteins E and C revealed that CD4+ T cells concomitantly producing IL-2 and TNF dominated the responses from vaccinees after each vaccine dose, whereas a control cohort of TBE patients responded mainly with all three cytokines. CD107a expression was not upregulated upon peptide stimulation in the vaccinees. However, CD154 (CD40L) expression on cytokine-positive memory CD4+ T cells significantly increased after the second vaccine dose. Taken together, TBE vaccination induced CD4+ T cell responses dominated by IL-2 and TNF production together with CD154 upregulation and a lower IFN-γ response compared with TBE patients. This response pattern was consistent after all three doses of TBE vaccine.

Immunogenicity of the Adjuvanted Recombinant Zoster Vaccine: Persistence and Anamnestic Response to Additional Doses Administered 10 Years After Primary Vaccination.

BACKGROUND: The adjuvanted recombinant zoster vaccine (RZV) is highly immunogenic and efficacious in adults ≥50 years of age. We evaluated (1) long-term immunogenicity of an initial 2-dose RZV schedule, by following up adults vaccinated at ≥60 years of age and by modeling, and (2) immunogenicity of 2 additional doses administered 10 years after initial vaccination. METHODS: Persistence of humoral and cell-mediated immune (CMI) responses to 2 initial RZV doses was assessed through 10 years after initial vaccination, and modeled through 20 years using a Piecewise, Power law and Fraser model. The immunogenicity and safety of 2 additional RZV doses were also evaluated. RESULTS: Seventy adults were enrolled. Ten years after initial vaccination, humoral and CMI responses were approximately 6-fold and 3.5-fold, respectively, above those before the initial vaccination levels. Predicted immune persistence through 20 years after initial vaccination was similar across the 3 models. Sixty-two participants (mean age [standard deviation], 82.6 [4.4] years) received ≥1 additional RZV dose. Strong anamnestic humoral and CMI responses were elicited by 1 additional dose, without further increases after a second additional dose. CONCLUSIONS: Immune responses to an initial 2-dose RZV course persisted for many years in older adults. Strong anamnestic immune responses can be induced by additional dosing 10 years after the initial 2-dose course. CLINICAL TRIALS REGISTRATION: NCT02735915.

High-Dose Chloroquine for Uncomplicated Plasmodium falciparum Malaria Is Well Tolerated and Causes Similar QT Interval Prolongation as Standard-Dose Chloroquine in Children.

Higher chloroquine doses can effectively treat up to 93 to 96% of malaria infections caused by Plasmodium falciparum carrying the resistance-conferring chloroquine resistance transporter (pfcrt) 76T allele. The tolerability of 50 (double the standard dose) and 70 mg/kg total chloroquine doses were assessed in this study. Fifteen 4- to 8-year-old children with uncomplicated malaria were given 10 mg/kg of chloroquine twice daily for 2 days and 5 mg/kg twice daily on the third day. Fifteen additional children were given 5 mg/kg twice daily for 2 more days. Chloroquine concentrations, blood pressure, electrocardiograms (ECGs), parasite density, and adverse events were assessed until day 28. Both dosages were well tolerated, and symptoms resolved by day 3 in parallel with increasing chloroquine concentrations. The median corrected QT (QTc) interval was 12 to 26 ms higher at expected peak concentrations than at day 0 (P < 0.001). Pfcrt 76T was associated with delayed parasite clearance. Day 28 clinical and parasitological responses against P. falciparum with pfcrt 76T were 57% (4/7) and 67% (4/6) after treatment with 50 and 70 mg/kg, respectively. Dosages were well tolerated, and no severe cardiac adverse events occurred. The QTc interval increase was similar to that found in adults taking 25 mg/kg of chloroquine. (This study has been registered at ClinicalTrials.gov under identifier NCT01814423.).

Efficacy of the Herpes Zoster Subunit Vaccine in Adults 70 Years of Age or Older.

BACKGROUND: A trial involving adults 50 years of age or older (ZOE-50) showed that the herpes zoster subunit vaccine (HZ/su) containing recombinant varicella-zoster virus glycoprotein E and the AS01B adjuvant system was associated with a risk of herpes zoster that was 97.2% lower than that associated with placebo. A second trial was performed concurrently at the same sites and examined the safety and efficacy of HZ/su in adults 70 years of age or older (ZOE-70). METHODS: This randomized, placebo-controlled, phase 3 trial was conducted in 18 countries and involved adults 70 years of age or older. Participants received two doses of HZ/su or placebo (assigned in a 1:1 ratio) administered intramuscularly 2 months apart. Vaccine efficacy against herpes zoster and postherpetic neuralgia was assessed in participants from ZOE-70 and in participants pooled from ZOE-70 and ZOE-50. RESULTS: In ZOE-70, 13,900 participants who could be evaluated (mean age, 75.6 years) received either HZ/su (6950 participants) or placebo (6950 participants). During a mean follow-up period of 3.7 years, herpes zoster occurred in 23 HZ/su recipients and in 223 placebo recipients (0.9 vs. 9.2 per 1000 person-years). Vaccine efficacy against herpes zoster was 89.8% (95% confidence interval [CI], 84.2 to 93.7; P<0.001) and was similar in participants 70 to 79 years of age (90.0%) and participants 80 years of age or older (89.1%). In pooled analyses of data from participants 70 years of age or older in ZOE-50 and ZOE-70 (16,596 participants), vaccine efficacy against herpes zoster was 91.3% (95% CI, 86.8 to 94.5; P<0.001), and vaccine efficacy against postherpetic neuralgia was 88.8% (95% CI, 68.7 to 97.1; P<0.001). Solicited reports of injection-site and systemic reactions within 7 days after injection were more frequent among HZ/su recipients than among placebo recipients (79.0% vs. 29.5%). Serious adverse events, potential immune-mediated diseases, and deaths occurred with similar frequencies in the two study groups. CONCLUSIONS: In our trial, HZ/su was found to reduce the risks of herpes zoster and postherpetic neuralgia among adults 70 years of age or older. (Funded by GlaxoSmithKline Biologicals; ZOE-50 and ZOE-70 ClinicalTrials.gov numbers, NCT01165177 and NCT01165229 .).

Distinction between serological responses following tick-borne encephalitis virus (TBEV) infection vs vaccination, Sweden 2017.

Tick-borne encephalitis virus (TBEV) is an important European vaccine-preventable pathogen. Discrimination of vaccine-induced antibodies from those elicited by infection is important. We studied anti-TBEV IgM/IgG responses, including avidity and neutralisation, by multiplex serology in 50 TBEV patients and 50 TBEV vaccinees. Infection induced antibodies reactive to both whole virus (WV) and non-structural protein 1 (NS1) in 48 clinical cases, whereas 47 TBEV vaccinees had WV, but not NS1 antibodies, enabling efficient discrimination of infection/vaccination.

High-Dose Chloroquine for Treatment of Chloroquine-Resistant Plasmodium falciparum Malaria.

BACKGROUND: Due to development of multidrug-resistant Plasmodium falciparum new antimalarial therapies are needed. In Guinea-Bissau, routinely used triple standard-dose chloroquine remained effective for decades despite the existence of "chloroquine-resistant" P. falciparum. This study aimed to determine the in vivo efficacy of higher chloroquine concentrations against P. falciparum with resistance-conferring genotypes. METHODS: Standard or double-dose chloroquine was given to 892 children aged <15 years with uncomplicated malaria during 3 clinical trials (2001-2008) with ≥ 35 days follow-up. The P. falciparum resistance-conferring genotype (pfcrt 76T) and day 7 chloroquine concentrations were determined. Data were divided into age groups (<5, 5-9, and 10-14 years) because concentrations increase with age when chloroquine is prescribed according to body weight. RESULTS: Adequate clinical and parasitological responses were 14%, 38%, and 39% after standard-dose and 66%, 84%, and 91% after double-dose chloroquine in children aged <5, 5-9, and 10-14 years, respectively, and infected with P. falciparum genotypes conferring chloroquine resistance (n = 195, P < .001). In parallel, median chloroquine concentrations were 471, 688, and 809 nmol/L for standard-dose and 1040, 1494, and 1585 nmol/L for double-dose chloroquine. CONCLUSIONS: Chloroquine resistance is dose dependent and can be overcome by higher, still well-tolerated doses.

Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine in Guinea-Bissau between 2003 and 2012.

In 2008, artemether-lumefantrine was introduced in Guinea-Bissau, West Africa, but quinine has also been commonly prescribed for the treatment of uncomplicated Plasmodium falciparum malaria. An efficacious high-dose chloroquine treatment regimen was used previously. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine have been described. P. falciparum chloroquine resistance transporter (pfcrt) K76T, pfmdr1 gene copy numbers, pfmdr1 polymorphisms N86Y and Y184F, and pfmdr1 sequences 1034 to 1246 were determined using PCR-based methods. Blood samples came from virtually all (n=1,806) children<15 years of age who had uncomplicated P. falciparum monoinfection and presented at a health center in suburban Bissau (from 2003 to 2012). The pfcrt K76T and pfmdr1 N86Y frequencies were stable, and seasonal changes were not seen from 2003 to 2007. Since 2007, the mean annual frequencies increased (P<0.001) for pfcrt 76T (24% to 57%), pfmdr1 N86 (72% to 83%), and pfcrt 76+pfmdr1 86 TN (10% to 27%), and pfcrt 76T accumulated during the high transmission season (P=0.001). The pfmdr1 86+184 NF frequency increased from 39% to 66% (from 2003 to 2011; P=0.004). One sample had two pfmdr1 gene copies. pfcrt 76T was associated with a lower parasite density (P<0.001). Following the discontinuation of an effective chloroquine regimen, probably highly artemether-lumefantrine-susceptible P. falciparum (with pfcrt 76T) accumulated, possibly due to suboptimal use of quinine and despite a fitness cost linked to pfcrt 76T. (The studies reported here were registered at ClinicalTrials.gov under registration no. NCT00137514 [PSB-2001-chl-amo], NCT00137566 [PSB-2004-paracetamol], NCT00426439 [PSB-2006-coartem], NCT01157689 [AL-eff 2010], and NCT01704508 [Eurartesim 2012].).

Lot-to-lot immunogenicity consistency of the respiratory syncytial virus prefusion F protein vaccine in older adults.

Background: Previous phase 3 studies showed that the AS01E-adjuvanted respiratory syncytial virus (RSV) prefusion F protein-based vaccine for older adults (RSVPreF3 OA) is well tolerated and efficacious in preventing RSV-associated lower respiratory tract disease in adults ≥ 60 years of age. This study evaluated lot-to-lot immunogenicity consistency, reactogenicity, and safety of three RSVPreF3 OA lots. Methods: This phase 3, multicenter, double-blind study randomized (1:1:1) participants ≥ 60 years of age to receive one of three RSVPreF3 OA lots. Serum RSVPreF3-binding immunoglobulin G (IgG) concentration was assessed at baseline and 30 days post-vaccination. Lot-to-lot consistency was demonstrated if the two-sided 95 % confidence intervals (CIs) of the RSVPreF3-binding IgG geometric mean concentration (GMC) ratios between each lot pair at 30 days post-vaccination were within 0.67 and 1.50. Solicited adverse events (AEs) within four days, unsolicited AEs within 30 days, and serious AEs (SAEs) and potential immune-mediated diseases within six months post-vaccination were recorded. Results: A total of 757 participants received RSVPreF3 OA, of whom 708 were included in the per-protocol set (234, 237, and 237 participants for each lot). Lot-to-lot consistency was demonstrated: GMC ratios were 1.06 (95 % CI: 0.94-1.21), 0.92 (0.81-1.04), and 0.87 (0.77-0.99) between the lot pairs (lot 1/2; 1/3; 2/3). For the three lots, the RSVPreF3-binding IgG concentration increased 11.84-, 11.29-, and 12.46-fold post-vaccination compared to baseline. The reporting rates of solicited and unsolicited AEs, SAEs, and potential immune-mediated diseases were balanced between lots. Twenty-one participants reported SAEs; one of these-a case of atrial fibrillation-was considered by the investigator as vaccine-related. SAEs with a fatal outcome were reported for four participants, none of which were considered by the investigator as vaccine-related. Conclusion: This study demonstrated lot-to-lot immunogenicity consistency of three RSVPreF3 OA vaccine lots and indicated that the vaccine had an acceptable safety profile.ClinicalTrials.gov: NCT05059301.

Cross-protective capacity of Japanese encephalitis (JE) vaccines against circulating heterologous JE virus genotypes.

Current Japanese encephalitis vaccines are derived from strains of genotype III, yet heterologous genotypes are emerging in endemic areas. Inactivated vaccines given to European travelers were found to elicit protective levels of neutralizing antibodies against heterologous strains of genotypes I-IV.

Selection of an adjuvant for seasonal influenza vaccine in elderly people: modelling immunogenicity from a randomized trial.

BACKGROUND: Improved influenza vaccines are needed to reduce influenza-associated complications in older adults. The aim of this study was to identify the optimal formulation of adjuvanted seasonal influenza vaccine for use in elderly people. METHODS: This observer-blind, randomized study assessed the optimal formulation of adjuvanted seasonal influenza vaccine based on immunogenicity and safety in participants aged ≥65 years. Participants were randomized (~200 per group) to receive one dose of non-adjuvanted vaccine or one of eight formulations of vaccine formulated with a squalene and tocopherol oil-in-water emulsion-based Adjuvant System (AS03(C), AS03(B) or AS03(A), with 2.97, 5.93 and 11.86 mg tocopherol, respectively) together with the immunostimulant monophosphoryl lipid A (MPL, doses of 0, 25 or 50 mg). Hemagglutination-inhibition (HI) antibody responses and T-cell responses were assessed on Day 0 and 21 days post-vaccination. The ratio of HI-based geometric mean titers in adjuvanted versus non-adjuvanted vaccine groups were calculated and the lower limit of the 90% confidence interval was transformed into a desirability index (a value between 0 and 1) in an experimental domain for each vaccine strain, and plotted in relation to the AS03 and MPL dose combination in the formulation. This model was used to assess the optimal formulation based on HI antibody titers. Reactogenicity and safety were also assessed. The immunogenicity and safety analyses were used to evaluate the optimal formulation of adjuvanted vaccine. RESULTS: In the HI antibody-based model, an AS03 dose-response was evident; responses against the A/H1N1 and A/H3N2 strains were higher for all adjuvanted formulations versus non-adjuvanted vaccine, and for the AS03(A)-MPL25, AS03(B)-MPL25 and AS03(B)-MPL50 formulations against the B strain. Modelling using more stringent criteria (post hoc) showed a clear dose-range effect for the AS03 component against all strains, whereas MPL showed a limited effect. Higher T-cell responses for adjuvanted versus non-adjuvanted vaccine were observed for all except two formulations (AS03(C) and AS03(B)-MPL25). Reactogenicity increased with increasing AS03 dosage, and with MPL. No safety concerns were raised. CONCLUSIONS: Five formulations containing AS03(A) or AS03(B) were identified as potential candidates to improve immune responses to influenza vaccination; AS03(B) without MPL showed the best balance between improved immunogenicity and acceptable reactogenicity. TRIAL REGISTRATION: This trial is registered at ClinicalTrials.gov, NCT00540592.

Seasonal variation of diarrhoeal pathogens among Guinea-Bissauan children under five years of age.

BACKGROUND: Diarrhoea remains a major cause of childhood morbidity and mortality in low-income countries (LICs). The frequency of diarrhoeal episodes may vary by season, yet few prospective cohort studies have examined seasonal variation among various diarrhoeal pathogens using multiplex qPCR to analyse bacterial, viral and parasitic pathogens. METHODS: We combined our recent qPCR data of diarrhoeal pathogens (nine bacterial, five viral and four parasitic) among Guinea-Bissauan children under five years old with individual background data, dividing by season. The associations of season (dry winter and rainy summer) and the various pathogens were explored among infants (0-11 months) and young children (12-59 months) and those with and without diarrhoea. RESULTS: Many bacterial pathogens, especially EAEC, ETEC and Campylobacter, and parasitic Cryptosporidium, prevailed in the rainy season, whereas many viruses, particularly the adenovirus, astrovirus and rotavirus proved common in the dry season. Noroviruses were found constantly throughout the year. Seasonal variation was observed in both age groups. CONCLUSION: In childhood diarrhoea in a West African LIC, seasonal variation appears to favour EAEC, ETEC, and Cryptosporidium in the rainy and viral pathogens in the dry season.

Safety and tolerability of frozen, capsulized autologous faecal microbiota transplantation. A randomized double blinded phase I clinical trial.

BACKGROUND: Faecal microbiota transplantation (FMT) is recommended treatment for recurrent Clostridioides difficile infection and is studied as a potential modifier of other gastrointestinal and systemic disorders. Autologous FMT limits the potential risks of donor transplant material and enables prophylactic treatment. Capsulized FMT is convenient and accessible, but safety data are lacking. AIMS: To describe safety and tolerability of capsules containing autologous FMT, compared to placebo, in healthy volunteers treated with antibiotics. METHOD: Healthy volunteers without antibiotic exposure during the past three months, that had a negative Clostridioides difficile stool sample, were recruited. Study persons donated faeces for production of capsules containing autologous microbiota. They were then given Clindamycin for seven days to disrupt the intestinal microbiota, which was followed by a two-day washout. Study persons were then randomized (1:1) to unsupervised treatment with autologous faecal matter or placebo, with two capsules twice daily for five days. A standardized questionnaire about side effects and tolerability, daily until day 28, and on days 60 and 180, was completed. RESULTS: Twenty-four study persons were included, all completed the treatment. One person from the placebo and FMT groups each, were lost to follow up from days 21 and 60, respectively. No study person experienced serious side effects, but severe fatigue was reported during the antibiotic period (n = 2). Reported side effects were mild to moderate and there were no significant differences between the groups. Reported general and intestinal health improved significantly and similarly in both groups after the antibiotic treatment. Time to normalized intestinal habits were 17 and 19 days from study start in the placebo group and the FMT group, respectively (p = 0.8). CONCLUSION: Capsulized frozen autologous faecal microbiota transplantation was safe and well tolerated but did not affect time to normalized intestinal habits compared to placebo. TRIAL REGISTRATION: EudraCT 2017-002418-30.

Coadministered pneumococcal conjugate vaccine decreases immune response to hepatitis A vaccine: a randomized controlled trial.

OBJECTIVES: We explored the influence of coadministration on safety and immunogenicity of the most common travellers' vaccine hepatitis A (HepA) and the pneumococcal conjugate vaccine (PCV) increasingly used both at home and before travel. METHODS: Volunteers aged ≥18 years (n = 305) were randomly assigned 1:1:1 into three groups receiving: 13-valent PCV (PCV13) + HepA, PCV13, or HepA. Anti-pneumococcal IgG concentrations, opsonophagocytic activity (OPA) titres, and total hepatitis A antibody (anti-HAV) concentrations were measured before and 28 ± 3 days after vaccination. Adverse events (AEs) were recorded over 4 weeks. RESULTS: After vaccination, the anti-HAV geometric mean concentration was significantly lower in the PCV13+HepA than the HepA group: 34.47 mIU/mL (95% CI: 26.42-44.97 mIU/mL) versus 72.94 mIU/mL (95% CI: 55.01-96.72 mIU/mL), p < 0.001. Anti-HAV ≥10 mIU/mL considered protective was reached by 71 of 85 (83.5%) in the PCV13+HepA group versus 76 of 79 (96.2%) in the HepA group, p 0.008. The increases in anti-pneumococcal IgG and OPA levels were comparable in the PCV13+HepA and PCV13 groups, apart from a bigger rise in the PCV13+HepA group for serotype 3 (one-way ANOVA: serotype 3 IgG p 0.010, OPA p 0.002). AEs proved more frequent among those receiving PCV13 than HepA, but simultaneous administration did not increase the rates: ≥one AE was reported by 45 of 56 (80.4%) PCV13, 43 of 54 (79.6%) PCV13+HepA, and 25 of 53 (47.2%) HepA recipients providing structured AE data. DISCUSSION: Coadministration of HepA and PCV13 did not cause safety concerns, nor did it impact the patients' response to PCV13, apart from serotype 3. However, coadministered PCV13 significantly impaired antibody responses to HepA.

A single dose of vero cell-derived Japanese encephalitis (JE) vaccine (Ixiaro) effectively boosts immunity in travelers primed with mouse brain-derived JE vaccines.

BACKGROUND: A significant part of the world population lives in areas with endemic Japanese encephalitis (JE). For travelers from nonendemic countries, Vero cell-derived vaccine (JE-VC; Ixiaro) has replaced traditional mouse brain-derived vaccines (JE-MB) associated with safety concerns. The 2 vaccines are derived from different viral strains: JE-VC from the SA14-14-2 strain and JE-MB from the Nakayama strain. No data exist regarding whether JE-VC can be used to boost immunity after a primary series of JE-MB; therefore, a primary series of JE-VC has been recommended to all travelers regardless of previous vaccination history. METHODS: One hundred twenty travelers were divided into 4 groups: Volunteers with no prior JE vaccination received primary immunization with (group 1) JE-MB or (group 2) JE-VC, and those primed with JE-MB received a single booster dose of (group 3) JE-MB or (group 4) JE-VC. Immune responses were tested before and 4-8 weeks after vaccination using plaque reduction neutralization test (PRNT) against both vaccine strains. RESULTS: In vaccine-naive travelers, the vaccination response rate for test strains Nakayama and SA14-14-2 was 100% and 87% after primary vaccination with JE-MB and 87% and 94% after JE-VC, respectively. Antibody levels depended on the target virus, with higher titers against homologous than heterologous PRNT(50) target strain (P < .001). In travelers primed with JE-MB, vaccination response rates were 91% and 91%, and 98% and 95% after a booster dose of JE-MB or JE-VC, respectively. Subgroup analysis revealed that a higher proportion of primed (98%/95%) than nonprimed (39%/42%) volunteers responded to a single dose of JE-VC (P < .001). CONCLUSIONS: A single dose of JE-VC effectively boosted immunity in JE-MB-primed travelers. Current recommendations should be reevaluated. CLINICAL TRIALS REGISTRATION: NCT01386827.

Similar efficacy and tolerability of double-dose chloroquine and artemether-lumefantrine for treatment of Plasmodium falciparum infection in Guinea-Bissau: a randomized trial.

BACKGROUND: In 2008, Guinea-Bissau introduced artemether-lumefantrine for treatment of uncomplicated malaria. Previously, 3 times the standard dose of chloroquine, that was probably efficacious against Plasmodium falciparum with the resistance-associated chloroquine-resistance transporter (pfcrt) 76T allele, was routinely used. The present study compared the efficacy and tolerability of a double standard dose of chloroquine with the efficacy and tolerability of artemether-lumefantrine. METHODS: In a randomized open-label clinical trial, artemether-lumefantrine or chloroquine (50 mg/kg) were given as 6 divided doses over 3 days to children aged 6 months--15 years who had uncomplicated P. falciparum monoinfection. Drug concentrations were measured on day 7. P. falciparum multidrug resistance gene N86Y and pfcrt K76T alleles were identified. RESULTS: The polymerase chain reaction-adjusted day 28 and 42 treatment efficacies were 162 (97%) of 168 and 155 (97%) of 161, respectively, for artemether-lumefantrine and 150 (95%) of 158 and 138 (94%) of 148, respectively, for chloroquine. When parasites with resistance-associated pfcrt 76T were treated, the day 28 efficacy of chloroquine was 87%. No severe drug-related adverse events were detected. Symptom resolution was similar with both treatments. CONCLUSIONS: Both treatments achieved the World Health Organization-recommended efficacy for antimalarials that will be adopted as policy. High-dose chloroquine treatment regimes should be further evaluated with the aim of assessing chloroquine as a potential partner drug to artemisinin derivatives. Clinical trials registration. NCT00426439.

Three-dose versus four-dose primary schedules for tick-borne encephalitis (TBE) vaccine FSME-immun for those aged 50 years or older: A single-centre, open-label, randomized controlled trial.

BACKGROUND: TBE vaccination failures among those past middle age have raised concern about immune response declining with age. We investigated immunogenicity of the TBE-vaccine FSME-Immun among those aged 50+ years using the standard three-dose primary series and alternative four-dose schedules. METHODS: In this single-centre, open-label, randomized controlled trial, 200 TBE-naive Swedish adults were given primary TBE vaccination with FSME-Immun. Those aged 50+ years (n = 150) were randomized to receive the standard three-dose (days 0-30-360) or one of two four-dose series (0-7-21-360; 0-30-90-360). For participants < 50 years (n = 50) the standard three-dose schedule was used. Titres of neutralizing antibodies were determined on days 0, 60, 120, 360, and 400. The main outcome was the log titre of TBE virus-specific neutralizing antibodies on day 400. RESULTS: The three-dose schedule yielded lower antibody titres among those aged 50+ years than the younger participants on day 400 (geometric mean titre 41 versus 74, p < 0.05). The older group showed higher titres for the four-dose 0-7-21-360 than the standard three-dose schedule both on day 400 (103 versus 41, p < 0.01; primary end point) and at the other testing points (days 60, 120, 360). Using the other four-dose schedule (0-30-90-360), no such difference was observed on day 400 (63 versus 41, NS). CONCLUSION: Immune response to the TBE vaccine declined with age. A four-dose schedule (0-7-21-360) may benefit those aged 50 years or older. This study is registered at ClinicalTrials.gov, NCT01361776.

Paracetamol versus placebo in treatment of non-severe malaria in children in Guinea-Bissau: a randomized controlled trial.

BACKGROUND: The current guidelines for treatment of malaria include paracetamol to children with fever. No convincing evidence for the beneficial effects of this practice exists. Studies show that time to parasite clearance is significantly longer in children treated with paracetamol, which questions the policy. Whether this is of clinical importance has not been investigated. METHODS: Children with Plasmodium falciparum monoinfection and ≥20 parasites per 200 leucocytes at the Bandim Health Centre, Guinea-Bissau were randomized to receive paracetamol or placebo together with chloroquine for three days in a double blind randomized study. Temperature and symptoms were recorded twice daily during treatment and on day 3. The participants were interviewed and a malaria film taken once weekly until day 35. The data is in the form of grouped failure-times, the outcome of interest being time until parasitaemia during follow-up. Mantel-Haenszel weighted odds ratios are given. Other differences between and within the two groups have been tested using the Chi-square test and Mann-Whitney U test. RESULTS: In the evening of the day of inclusion, the temperature was slightly, but statistically insignificant, higher in the placebo group and significantly more children complained of headache. At no other time was a significant difference in temperature or symptoms detected. However, 6 children from the placebo-group as compared to two children from the paracetamol-group were admitted to hospital with high fever and convulsions by day 3. No differences in the cumulative percentages of children with adequate clinical and parasitological response were found in the intention-to-treat analysis or in the per-protocol analysis. CONCLUSION: Fewer children had early treatment failure and the mean temperature was slightly lower in the afternoon on day 0 in the paracetamol group. However, the cumulative adequate clinical and parasitological cure rates were not significantly different during the period of study. It is doubtful whether adding paracetamol to the treatment of uncomplicated malaria in children is beneficial. TRIAL REGISTRATION: NCT00137566.