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Background Safe, effective vaccines against coronavirus disease 2019 (Covid-19) are urgently needed in children younger than 12 years of age. Methods A phase 1, dose-finding study and an ongoing phase 2-3 randomized trial are being conducted to investigate the safety, immunogenicity, and efficacy of two doses of the BNT162b2 vaccine administered 21 days apart in children 6 months to 11 years of age. We present results for 5-to-11-year-old children. In the phase 2-3 trial, participants were randomly assigned in a 2:1 ratio to receive two doses of either the BNT162b2 vaccine at the dose level identified during the open-label phase 1 study or placebo. Immune responses 1 month after the second dose of BNT162b2 were immunologically bridged to those in 16-to-25-year-olds from the pivotal trial of two 30-μg doses of BNT162b2. Vaccine efficacy against Covid-19 at 7 days or more after the second dose was assessed. Results During the phase 1 study, a total of 48 children 5 to 11 years of age received 10 μg, 20 μg, or 30 μg of the BNT162b2 vaccine (16 children at each dose level). On the basis of reactogenicity and immunogenicity, a dose level of 10 μg was selected for further study. In the phase 2-3 trial, a total of 2268 children were randomly assigned to receive the BNT162b2 vaccine (1517 children) or placebo (751 children). At data cutoff, the median follow-up was 2.3 months. In the 5-to-11-year-olds, as in other age groups, the BNT162b2 vaccine had a favorable safety profile. No vaccine-related serious adverse events were noted. One month after the second dose, the geometric mean ratio of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing titers in 5-to-11-year-olds to those in 16-to-25-year-olds was 1.04 (95% confidence interval [CI], 0.93 to 1.18), a ratio meeting the prespecified immunogenicity success criterion (lower bound of two-sided 95% CI, >0.67; geometric mean ratio point estimate, ≥0.8). Covid-19 with onset 7 days or more after the second dose was reported in three recipients of the BNT162b2 vaccine and in 16 placebo recipients (vaccine efficacy, 90.7%; 95% CI, 67.7 to 98.3). Conclusions A Covid-19 vaccination regimen consisting of two 10-μg doses of BNT162b2 administered 21 days apart was found to be safe, immunogenic, and efficacious in children 5 to 11 years of age. (Funded by BioNTech and Pfizer; ClinicalTrials.gov number, NCT04816643.).

Background Infection is a leading cause of admission to intensive care units (ICUs), with critically ill patients often receiving empiric broad-spectrum antibiotics. Nevertheless, a dedicated infectious diseases (ID) consultation and stewardship team is not routinely established. An ID–critical care medicine (ID-CCM) pilot program was designed at a 400-bed tertiary care hospital in which an ID attending was assigned to participate in daily rounds with the ICU team, as well as provide ID consultation on select patients. We sought to evaluate the impact of this dedicated ID program on antibiotic utilization and clinical outcomes in patients admitted to the ICU. Methods In this single-site retrospective study, we analyzed antibiotic utilization and clinical outcomes in patients admitted to an ICU during the postintervention period from January 1 to December 31, 2017, and compared it to antibiotic utilization in the same ICUs during the preintervention period from January 1 to December 31, 2015. Results Our data showed a statistically significant reduction in usage of most frequently prescribed antibiotics including vancomycin, piperacillin-tazobactam, and cefepime during the intervention period. When compared to the preintervention period there was no difference in-hospital mortality, hospital length of stay, and readmission. Conclusions With this multidisciplinary intervention, we saw a decrease in the use of the most frequently prescribed broad-spectrum antibiotics without a negative impact on clinical outcomes. Our study shows that the implementation of an ID-CCM service is a feasible way to promote antibiotic stewardship in the ICU and can be used as a strategy to reduce unnecessary patient exposure to broad-spectrum agents.

Gastrointestinal mucormycosis is a rare life-threatening infection to which neutropenic patients are especially vulnerable. Mycotypha microspora is a mucormycete that has not been described as a human pathogen. We discuss the successful eradication of gastrointestinal Mycotypha microspora in a neutropenic patient with simultaneous pulmonary Aspergillus fumigatus infection.

Background Medical tourism is increasingly popular for elective cosmetic surgical procedures. However, medical tourism has been accompanied by reports of post-surgical infections due to rapidly growing mycobacteria (RGM). The authors' experience working with patients with RGM infections who have returned to the USA after traveling abroad for cosmetic surgical procedures is described here. Methods Patients who developed RGM infections after undergoing cosmetic surgeries abroad and who presented at the Montefiore Medical Center (Bronx, New York, USA) between August 2015 and June 2016 were identified. A review of patient medical records was performed. Results Four patients who presented with culture-proven RGM infections at the sites of recent cosmetic procedures were identified. All patients were treated with a combination of antibiotics and aggressive surgical treatment. Conclusions This case series of RGM infections following recent cosmetic surgeries abroad highlights the risks of medical tourism. Close monitoring of affected patients by surgical and infectious disease specialties is necessary, as aggressive surgical debridement combined with appropriate antibiotic regimens is needed to achieve cure. Given the increasing reports of post-surgical RGM infections, consultants should have a low threshold for suspecting RGM, as rapid diagnosis may accelerate the initiation of targeted treatment and minimize morbidity.

Exophiala (Wangiella) dermatitidis is an emerging dematiaceous fungus associated with high mortality rates and is a rare cause of endocarditis. We describe the first case of E. dermatitidis endocarditis of a prosthetic aortic valve and aortic graft in an immune competent patient with no clear risk factors of hematological acquisition.

We engaged medical students with antimicrobial stewardship (AS) and resistance (AMR) through patient stories and a panel on AMR advocacy with experts from the Centers for Disease Control and Prevention and the Infectious Diseases Society of America. Students were surveyed on their perceptions about AS and AMR (response rate=139/166, 84%).

Objective Severe sepsis and septic shock (SS/SS) treatment bundles reduce mortality, and early infectious diseases (ID) consultation also improves patient outcomes. We retrospectively examined whether early ID consultation further improves outcomes in Emergency Department (ED) patients with SS/SS who complete the sepsis bundle. Method We included 248 adult ED patients with SS/SS who completed the 3-hour bundle. Patients with ID consultation within 12 hours of ED triage (n = 111; early ID) were compared with patients who received standard care (n = 137) for in-hospital mortality, 30-day readmission, length of hospital stay (LOS), and antibiotic management. A competing risk survival analysis model compared risks of in-hospital mortality and discharge alive between groups. Results In-hospital mortality was lower in the early ID group unadjusted (24.3% vs 38.0%, P = .02) and adjusted for covariates (odds ratio, 0.47; 95% confidence interval (CI), 0.25–0.89; P = .02). There was no significant difference in 30-day readmission (22.6% vs 23.5%, P = .89) or median LOS (10.2 vs 12.1 days, P = .15) among patients who survived. A trend toward shorter time to antibiotic de-escalation in the early ID group (log-rank test P = .07) was observed. Early ID consultation was protective of in-hospital mortality (adjusted subdistribution hazard ratio (asHR), 0.60; 95% CI 0.36–1.00, P = .0497) and predictive of discharge alive (asHR 1.58, 95% CI, 1.11–2.23; P-value .01) after adjustment. Conclusions Among patients receiving the SS/SS bundle, early ID consultation was associated with a 40% risk reduction for in-hospital mortality. The impact of team-based care and de-escalation on SS/SS outcomes warrants further study., Early infectious diseases consult within 12 hours of emergency department triage was associated with lower mortality in patients with severe sepsis or septic shock who completed the 3-hour sepsis bundle.

Background While PET using F-FDG is most commonly used for imaging malignant tumors, vaccination is known to cause transient inflammation of lymph nodes inducing positive findings on F-FDG PET scans. The pattern, magnitude, and duration of lymph node activation following vaccination have not been clearly defined. Furthermore, the addition of adjuvants to vaccines can further enhance the immune response. The presented study was designed to define lymph node activation following administration of the Food and Drug Administration-licensed human papillomavirus vaccines, Cervarix and Gardasil, which contain similar antigens with different adjuvants. Methods Twenty-seven women aged 18 to 25 years were randomized to receive either Cervarix or Gardasil in the clinical trial VRC 900. Fifteen subjects participated in the PET/CT portion of the trial and received scans of lymph node activation at prevaccination and "1 week" (8-14 days) and "1 month" (23-36 days) after the first or third vaccination. Results PET/CT scans revealed that all vaccine recipients had ipsilateral axillary lymph node activity. Three of 4 Cervarix recipients also showed contralateral lymph node activity 1 month after the first vaccination. For both Cervarix and Gardasil, the SUV activity resolved over time, with activity extended up to day 37 after the first and third vaccinations. Conclusions Following intramuscular vaccination, there were no major differences between duration of uptake and intensity of SUV between Cervarix and Gardasil recipients in ipsilateral axillary lymph nodes. Contralateral node activation was detected up to 1 month after the first vaccination in Cervarix recipients only, possibly reflecting differences in vaccine adjuvant formulation.

BackgroundA streamlined transition from inpatient to outpatient care can decrease 30-day readmissions. Outpatient parenteral antibiotic therapy (OPAT) programs have not reduced readmissions; an OPAT bundle has been suggested to improve outcomes. We implemented a transition-of-care (TOC) OPAT bundle and assessed the effects on all-cause, 30-day hospital readmission.MethodsRetrospectively, patients receiving postdischarge intravenous antibiotics were evaluated before and after implementation of a TOC-OPAT program in Bronx, New York, between July, 2015 and February, 2016. Pearson’s χ2 test was used to compare 30-day readmissions between groups, and logistic regression was used to adjust for covariates. Time from discharge to readmission was analyzed to assess readmission risk, using log-rank test to compare survival curves and Cox proportional hazards model to adjust for covariates. Secondary outcomes, 30-day emergency department (ED) visits, and mortality were analyzed similarly.ResultsCompared with previous standard care (n = 184), the TOC-OPAT group (n = 146) had significantly lower 30-day readmissions before (13.0% vs 26.1%, P < .01) and after adjustment for covariates (odds ratio [OR] = 0.51; 95% confidence interval [CI], 0.27–0.94; P = .03). In time-dependent analyses, TOC-OPAT patients were at significantly lower risk for readmission (log-rank test, P < .01; hazard ratio = 0.56; 95% CI, 0.32–0.97; P = .04). Propensity-matched sensitivity analysis showed lower readmissions in the TOC-OPAT group (13.6% vs 24.6%, P = .04), which was attenuated after adjustment (OR = 0.51; 95% CI, 0.25–1.05; P = .07). Mortality and ED visits were similar in both groups.ConclusionsOur TOC-OPAT patients had reduced 30-day readmissions compared with the previous standard of care. An effective TOC-OPAT bundle can successfully improve patient outcomes in an economically disadvantaged area.

Two HPV virus-like particle (VLP) vaccines, HPV-16/18 (GlaxoSmithKline, Cervarix®) and HPV-6/11/16/18 (Merck, Gardasil®), are currently licensed in the United States. Given the similar antigenic content but different adjuvant formulations in the 2 vaccines, they provide an efficient method for evaluating adjuvants and comparing the kinetics of the innate and adaptive immune responses. We randomized women to receive either Cervarix® or Gardasil®, followed 6 month vaccination delivery schedules per manufacturer's recommendations, and analyzed the humoral immune response, T cell response, and circulating plasma cytokine levels in response to vaccination. Cervarix® recipients had higher anti-HPV-16 antibody and neutralization titers at month 7, and elevated anti-HPV-18 antibody and neutralization titers at months 7 and 12. Antibody avidity was similar for the 2 vaccines. HPV-31 was the only phylogenetically related non-vaccine HPV type, for which there is evidence of cross-protection, to be cross-neutralized and only in response to Cervarix®. Comparing CD4+ T cell cytokine responses at month 12, there was a trend of increased levels of IL-2 and TNF-α in the Cervarix® groups versus the Gardasil® groups that was consistent across all 4 tested HPV types (16/18/33/45). Elevated levels of circulating plasma cytokine/chemokines were observed post first vaccination in Gardasil® recipients and proinflammatory cytokines were elevated following 1st and 3rd Cervarix® vaccinations. Cervarix® and Gardasil® are both highly immunogenic vaccines. Higher antibody levels and CD4 T cell responses were achieved with Cervarix® after 3 doses, although similar affinity maturation was measured for the 2 vaccines. The clinical implications of the differences in immune responses are unknown.

Background Infection is a leading cause of admission to intensive care units (ICU), with critically ill patients often receiving a high volume of empiric broad-spectrum antibiotics. Nevertheless, a dedicated infectious diseases (ID) consultation and stewardship team is not routinely implemented. An ID-Critical Care Medicine (ID-CCM) pilot program was designed at a large tertiary hospital in which an ID attending was assigned to participate in daily rounds with the ICU team, as well as provide an ID consult on select patients. We sought to evaluate the impact of this dedicated ID consultation and stewardship program on antibiotic utilization in the ICU. Methods This is an IRB-approved single-site retrospective study. We analyzed antibiotic utilization in the ICU during the post-intervention period from January 1, 2017 to December 31, 2017 and compared it to antibiotic utilization in the same ICU during the pre-intervention period from January 1, 2015 to December 31, 2015. Using Poisson regression analysis, we evaluated antibiotic utilization of each agent, expressed as days of therapy (DOT) per 1,000 patient-days, between the two groups. Results The six most commonly used broad-spectrum antibiotic agents were included in the final analysis. During the intervention period, statistically significant reductions were seen in cefepime (131 vs. 101 DOT per 1,000 patient-days, P = 0.01), piperacillin-tazobactam (268 vs. 251 DOT per 1,000 patient-days, P = 0.02) and vancomycin (265 vs. 228 DOT per 1,000 patient-days, P = 0.01). The utilization of other antibiotics including daptomycin, linezolid, and meropenem did not differ significantly (Figure 1). Conclusion With this multidisciplinary intervention, we saw a decrease in the use of the most frequently administered broad-spectrum antibiotics. Our study shows that the implementation of an ID-CCM service is a feasible way to promote antibiotic stewardship in the ICU and can be used as a strategy to reduce unnecessary patient exposure to broad-spectrum agents. Disclosures All Authors: No reported Disclosures.

Background Severe sepsis and septic shock bundles have been shown to reduce mortality. Infectious Diseases (ID) consultation, particularly early in a hospital course, is associated with improved patient outcomes. Antibiotic Stewardship Program (ASP) decision support in the ED has also shown clinical benefit. We aim to examine the addition of early ID consultation to existing ASP decision support in the Emergency Department (ED) in patients with sepsis with organ dysfunction and/or shock (SODS) who completed the 3-hour bundle. Methods This is a retrospective study of 248 adult patients with clinical SODS who met inclusion criteria per Center for Medicare and Medicaid Services SEP-1 core measure in the ED and completed the recommended 3-hour sepsis bundle using ASP decision support tools. Patients who received ID consultation in the first 12 hours after ED triage (n = 111) were compared with patients who received standard care (n = 137). Pearson’s chi-square test was used to compare groups for all-cause 30-day readmissions and in-hospital mortality. Logistic regression was used to adjust for covariates (age, race/ethnicity, Charlson score, lactate level ≥4, hypotension, recent hospital admission, recent IV antibiotics, history of MDR organisms, intra-abdominal source of infection). Time from ED triage to death and time to hospital discharge alive were analyzed using Fine and Gray models for competing risks. Results In-hospital mortality was lower among patients who received early ID consultation (24.3% vs. 38.0%, P = 0.0220). This association persisted after adjustment for covariates (odds ratio 0.49, 95% CI 0.26–0.91, P = 0.0236). There was no significant difference in 30-day readmissions between groups (22.6% vs. 23.5%, P = 0.8883). Early ID consultation was predictive of time to death (adjusted hazard ratio 0.58, 95% CI 0.35–0.98, P = 0.0406) and time to hospital discharge alive (adjusted hazard ratio 1.51, 95% CI 1.07–2.12, P-value 0.0174) after adjustment. Conclusion Early ID consultation was associated with lower mortality and time to hospital discharge among patients receiving the 3-hour severe sepsis/septic shock bundle. Further investigation is needed to explore specific interventions by ID consultants that might reduce the risk of mortality in this population. Disclosures All authors: No reported disclosures.

An attenuated Plasmodium falciparum (Pf) sporozoite (SPZ) vaccine, PfSPZ Vaccine, is highly protective against controlled human malaria infection (CHMI) 3 weeks after immunization, but the durability of protection is unknown. We assessed how vaccine dosage, regimen, and route of administration affected durable protection in malaria-naive adults. After four intravenous immunizations with 2.7 × 10(5) PfSPZ, 6/11 (55%) vaccinated subjects remained without parasitemia following CHMI 21 weeks after immunization. Five non-parasitemic subjects from this dosage group underwent repeat CHMI at 59 weeks, and none developed parasitemia. Although Pf-specific serum antibody levels correlated with protection up to 21-25 weeks after immunization, antibody levels waned substantially by 59 weeks. Pf-specific T cell responses also declined in blood by 59 weeks. To determine whether T cell responses in blood reflected responses in liver, we vaccinated nonhuman primates with PfSPZ Vaccine. Pf-specific interferon-γ-producing CD8 T cells were present at ∼100-fold higher frequencies in liver than in blood. Our findings suggest that PfSPZ Vaccine conferred durable protection to malaria through long-lived tissue-resident T cells and that administration of higher doses may further enhance protection.

Annual influenza vaccination reduces the risks of influenza when the vaccines are well matched to circulating strains, but development of an approach that induces broader and more durable immune responses would be beneficial. We conducted two companion Phase 1 studies, VRC 307 and VRC 309, over sequential seasons (2008–2009 and 2009–2010) in which only the influenza B strain component of the vaccines differed. Objectives were safety and immunogenicity of prime–boost vaccination schedules. A schedule of DNA vaccine encoding for seasonal influenza hemagglutinins (HA) prime followed by seasonal trivalent influenza inactivated vaccine (IIV3) boost (HA DNA–IIV3) was compared to placebo (PBS)–IIV3 or IIV3–IIV3. Cumulatively, 111 adults were randomized to HA DNA–IIV3 (n = 66), PBS–IIV3 (n = 25) or IIV3–IIV3 (n = 20). Safety was assessed by clinical observations, laboratory parameters and 7-day solicited reactogenicity. The seasonal HA DNA prime–IIV3 boost regimen was evaluated as safe and well tolerated. There were no serious adverse events. The local and systemic reactogenicity for HA DNA, IIV and placebo were reported predominantly as none or mild within the first 5 days post-vaccination. There was no significant difference in immunogenicity detected between the treatment groups as evaluated by hemagglutination inhibition (HAI) assay. The studies demonstrated the safety and immunogenicity of seasonal HA DNA–IIV3 regimen, but the 3–4 week prime–boost interval was suboptimal for improving influenza-specific immune responses. This is consistent with observations in avian H5 DNA vaccine prime–boost studies in which a long interval, but not a short interval, was associated with improved immunogenicity. Trial Registration: NCT00858611 for VRC 307 and NCT00995982 for VRC 309.

Background The efficacy of current influenza vaccines is limited in vulnerable populations. DNA vaccines can be produced rapidly, and may offer a potential strategy to improve vaccine immunogenicity, indicated by studies with H5 influenza DNA vaccine prime followed by inactivated vaccine boost. Methods Four sites enrolled healthy adults, randomized to receive 2011/12 seasonal influenza DNA vaccine prime (n=65) or phosphate buffered saline (PBS) (n=66) administered intramuscularly with Biojector. All subjects received the 2012/13 seasonal inactivated influenza vaccine, trivalent (IIV3) 36 weeks after the priming injection. Vaccine safety and tolerability was the primary objective and measurement of antibody response by hemagglutination inhibition (HAI) was the secondary objective. Results The DNA vaccine prime-IIV3 boost regimen was safe and well tolerated. Significant differences in HAI responses between the DNA vaccine prime and the PBS prime groups were not detected in this study. Conclusion While DNA priming significantly improved the response to a conventional monovalent H5 vaccine in a previous study, it was not effective in adults using seasonal influenza strains, possibly due to pre-existing immunity to the prime, unmatched prime and boost antigens, or the lengthy 36 week boost interval. Careful optimization of the DNA prime-IIV3 boost regimen as related to antigen matching, interval between vaccinations, and pre-existing immune responses to influenza is likely to be needed in further evaluations of this vaccine strategy. In particular, testing this concept in younger age groups with less prior exposure to seasonal influenza strains may be informative. Trial Registration ClinicalTrials.gov NCT01498718

Chikungunya virus--a mosquito-borne alphavirus--is endemic in Africa and south and southeast Asia and has recently emerged in the Caribbean. No drugs or vaccines are available for treatment or prevention. We aimed to assess the safety, tolerability, and immunogenicity of a new candidate vaccine.VRC 311 was a phase 1, dose-escalation, open-label clinical trial of a virus-like particle (VLP) chikungunya virus vaccine, VRC-CHKVLP059-00-VP, in healthy adults aged 18-50 years who were enrolled at the National Institutes of Health Clinical Center (Bethesda, MD, USA). Participants were assigned to sequential dose level groups to receive vaccinations at 10 μg, 20 μg, or 40 μg on weeks 0, 4, and 20, with follow-up for 44 weeks after enrolment. The primary endpoints were safety and tolerability of the vaccine. Secondary endpoints were chikungunya virus-specific immune responses assessed by ELISA and neutralising antibody assays. This trial is registered with ClinicalTrials.gov, NCT01489358.25 participants were enrolled from Dec 12, 2011, to March 22, 2012, into the three dosage groups: 10 μg (n=5), 20 μg (n=10), and 40 μg (n=10). The protocol was completed by all five participants at the 10 μg dose, all ten participants at the 20 μg dose, and eight of ten participants at the 40 μg dose; non-completions were for personal circumstances unrelated to adverse events. 73 vaccinations were administered. All injections were well tolerated, with no serious adverse events reported. Neutralising antibodies were detected in all dose groups after the second vaccination (geometric mean titres of the half maximum inhibitory concentration: 2688 in the 10 μg group, 1775 in the 20 μg group, and 7246 in the 40 μg group), and a significant boost occurred after the third vaccination in all dose groups (10 μg group p=0·0197, 20 μg group p0·0001, and 40 μg group p0·0001). 4 weeks after the third vaccination, the geometric mean titres of the half maximum inhibitory concentration were 8745 for the 10 μg group, 4525 for the 20 μg group, and 5390 for the 40 μg group.The chikungunya VLP vaccine was immunogenic, safe, and well tolerated. This study represents an important step in vaccine development to combat this rapidly emerging pathogen. Further studies should be done in a larger number of participants and in more diverse populations.Intramural Research Program of the Vaccine Research Center, National Institute of Allergy and Infectious Diseases, and National Institutes of Health.

Malaria Sporozoite Vaccine Each year, hundreds of millions of people are infected with Plasmodium falciparum , the mosquito-borne parasite that causes malaria. A preventative vaccine is greatly needed. Seder et al. (p. 1359 , published online 8 August; see the Perspective by Good ) now report the results from a phase I clinical trial where subjects were immunized intravenously with a whole, attenuated sporozoite vaccine. Three of 9 subjects who received four doses and zero of 6 subjects who received five doses of the vaccine went on to develop malaria after controlled malaria infection. Both antibody titers and cellular immune responses correlated positively with the dose of vaccine received, suggesting that both arms of the adaptive immune response may have participated in the observed protection.

Recent case reports of viral hemorrhagic fever in Europe and the United States have raised concerns about the possibility for increased importation of filoviruses to non-endemic areas. This emerging threat is concerning because of the increase in global air travel and the rise of tourism in central and eastern Africa and the greater dispersion of military troops to areas of infectious disease outbreaks. Marburg viruses (MARV) and Ebola viruses (EBOV) have been associated with outbreaks of severe hemorrhagic fever involving high mortality (25 – 90% case fatality rates). First recognized in 1967 and 1976 respectively, subtypes of MARV and EBOV are the only known viruses of the Filoviridae family, and are among the world’s most virulent pathogens. This article focuses on information relevant for health care practitioners in travel medicine to include, the epidemiology and clinical features of filovirus infection and efforts toward development of a filovirus vaccine.

Background Needle-free delivery improves the immunogenicity of DNA vaccines but is also associated with more local reactogenicity. Here we report the first comparison of Biojector and needle administration of a candidate rAd5 HIV vaccine. Methods Thirty-one adults, 18–55 years, 20 naive and 11 prior rAd5 vaccine recipients were randomized to receive single rAd5 vaccine via needle or Biojector IM injection at 1010 PU in a Phase I open label clinical trial. Solicited reactogenicity was collected for 5 days; clinical safety and immunogenicity follow-up was continued for 24 weeks. Results Overall, injections by either method were well tolerated. There were no serious adverse events. Frequency of any local reactogenicity was 16/16 (100%) for Biojector compared to 11/15 (73%) for needle injections. There was no difference in HIV Env-specific antibody response between Biojector and needle delivery. Env-specific antibody responses were more than 10-fold higher in subjects receiving a booster dose of rAd5 vaccine than after a single dose delivered by either method regardless of interval between prime and boost. Conclusions Biojector delivery did not improve antibody responses to the rAd5 vaccine compared to needle administration. Homologous boosting with rAd5 gene-based vectors can boost insert-specific antibody responses despite pre-existing vector-specific immunity. Trial Registration Clinicaltrials.gov NCT00709605 NCT00709605