The Durability of Antibody Responses of Two Doses of High-Dose Relative to Two Doses of Standard-Dose Inactivated Influenza Vaccine in Pediatric Hematopoietic Cell Transplant Recipients: A Multi-Center Randomized Controlled Trial

BACKGROUND

Our previous study established a 2-dose regimen of high-dose trivalent influenza vaccine (HD-TIV) to be immunogenically superior compared to a 2-dose regimen of standard-dose quadrivalent influenza vaccine (SD-QIV) in pediatric allogeneic hematopoietic cell transplant (HCT) recipients. However, the durability of immunogenicity and the role of time post-HCT at immunization as an effect modifier are unknown.

METHODS

This phase II, multi-center, double-blinded, randomized controlled trial compared HD-TIV to SD-QIV in children 3-17 years old who were 3-35 months post-allogeneic HCT, with each formulation administered twice, 28-42 days apart. Hemagglutination inhibition (HAI) titers were measured at baseline, 28-42 days following each dose, and 138-222 days after the second dose. Using linear mixed effects models, we estimated adjusted geometric mean HAI titer ratios (aGMR: HD-TIV/SD-QIV) to influenza antigens. Early and late periods were defined as 3-5 and 6-35 months post-HCT, respectively.

RESULTS

During 3 influenza seasons (2016-2019), 170 participants were randomized to receive HD-TIV (n = 85) or SD-QIV (n = 85). HAI titers maintained significant elevations above baseline for both vaccine formulations, although the relative immunogenic benefit of HD-TIV to SD-QIV waned during the study. A 2-dose series of HD-TIV administered late post-HCT was associated with higher GMTs compared to the early post-HCT period (late group: A/H1N1 aGMR = 2.16, 95% confidence interval [CI] = [1.14-4.08]; A/H3N2 aGMR = 3.20, 95% CI = [1.60-6.39]; B/Victoria aGMR = 1.91, 95% CI = [1.01-3.60]; early group: A/H1N1 aGMR = 1.03, 95% CI = [0.59-1.80]; A/H3N2 aGMR = 1.23, 95% CI = [0.68-2.25]; B/Victoria aGMR = 1.06, 95% CI = [0.56-2.03]).

CONCLUSIONS

Two doses of HD-TIV were more immunogenic than SD-QIV, especially when administered ≥6 months post-HCT. Both groups maintained higher titers compared to baseline throughout the season.

CLINICAL TRIALS REGISTRATION

NCT02860039.

The Roles of Glucagon-Like Peptide 1 (GLP-1) Receptor Agonists and Sodium-Glucose Cotransporter 2 (SGLT-2) Inhibitors in Decreasing the Occurrence of Adverse Cardiorenal Events in Patients With Type 2 Diabetes

Diabetes mellitus is a metabolic disorder characterized by increased serum glucose due to errors in insulin production or response. The prevalence of diabetes mellitus has continued to rise globally over the years, with roughly 7079 persons per 100,000 expected to be impacted by 2030. A vast number of patients with diabetes mellitus experience unfavorable side effects such as weight gain, hypoglycemia, and hepatorenal toxicity from the several diabetic medications available. These adverse effects may result in life-threatening consequences with a high likelihood of occurrence; therefore, ongoing efforts continue to develop medications with improved tolerability and better glycemic control. Glucagon-like peptide-1 receptor agonists (GLP-1RA) and sodium-glucose cotransporter 2 inhibitors (SGLT-2i) are examples of new innovative targeted therapies to manage diabetes mellitus and potentially improve cardiorenal conditions. This review article details the specific mechanisms of action, potential side effects, and cardiorenal benefits of GLP-1RA and SGLT-2i therapies to fully understand their roles in combating type 2 diabetes mellitus (T2D).

Characteristics of GII.4 Norovirus Versus Other Genotypes in Sporadic Pediatric Infections in Davidson County, Tennessee, USA

BACKGROUND

Norovirus is a leading cause of epidemic acute gastroenteritis (AGE), with most outbreaks occurring during winter. The majority of outbreaks are caused by GII.4 noroviruses; however, data to support whether this is true for sporadic medically attended AGE are limited. Therefore, we sought to compare the clinical characteristics and seasonality of GII.4 vs non-GII.4 viruses.

METHODS

Children aged 15 days -17 years with AGE symptoms were recruited from the outpatient, emergency department, and inpatient settings at Vanderbilt Children's Hospital, Davidson County, Nashville, Tennessee, from December 2012 -November 2015. Stool specimens were tested using qRT-PCR for GI and GII noroviruses and subsequently genotyped by sequencing a partial region of the capsid gene.

RESULTS

A total of 3705 patients were enrolled, and stool specimens were collected and tested from 2885 (78%) enrollees. Overall, 636 (22%) samples were norovirus-positive, of which 567 (89%) were GII. Of the 460 (81%) genotyped GII-positive samples, 233 (51%) were typed as GII.4 and 227 (49%) as non-GII.4. Compared with children with non-GII.4 infections, children with GII.4 infections were younger, more likely to have diarrhea, and more likely to receive oral rehydration fluids. Norovirus was detected year-round and peaked during winter.

CONCLUSIONS

Approximately 40% of sporadic pediatric norovirus AGE cases were caused by GII.4 norovirus. Children infected with GII.4 had more severe symptoms that required more medical care. Seasonal variations were noticed among different genotypes. These data highlight the importance of continuous norovirus surveillance and provide important information on which strains pediatric norovirus vaccines should protect against.

Temporal and Genotypic Associations of Sporadic Norovirus Gastroenteritis and Reported Norovirus Outbreaks in Middle Tennessee, 2012-2016

BACKGROUND

In the United States, surveillance of norovirus gastroenteritis is largely restricted to outbreaks, limiting our knowledge of the contribution of sporadic illness to the overall impact on reported outbreaks. Understanding norovirus transmission dynamics is vital for improving preventive measures, including norovirus vaccine development.

METHODS

We analyzed seasonal patterns and genotypic distribution between sporadic pediatric norovirus cases and reported norovirus outbreaks in middle Tennessee. Sporadic cases were ascertained via the New Vaccine Surveillance Network in a single county, while reported norovirus outbreaks from 7 middle Tennessee counties were included in the study. We investigated the predictive value of sporadic cases on outbreaks using a 2-state discrete Markov model.

RESULTS

Between December 2012 and June 2016, there were 755 pediatric sporadic norovirus cases and 45 reported outbreaks. Almost half (42.2%) of outbreaks occurred in long-term care facilities. Most sporadic cases (74.9%) and reported outbreaks (86.8%) occurred between November and April. Peak sporadic norovirus activity was often contemporaneous with outbreak occurrence. Among both sporadic cases and outbreaks, GII genogroup noroviruses were most prevalent (90.1% and 83.3%), with GII.4 being the dominant genotype (39.0% and 52.8%). The predictive model suggested that the 3-day moving average of sporadic cases was positively associated with the probability of an outbreak occurring.

CONCLUSIONS

Despite the demographic differences between the surveillance populations, the seasonal and genotypic associations between sporadic cases and outbreaks are suggestive of contemporaneous community transmission. Public health agencies may use this knowledge to expand surveillance and identify target populations for interventions, including future vaccines.

The Changing Landscape of Pediatric Viral Enteropathogens in the Post-Rotavirus Vaccine Era

BACKGROUND

Acute gastroenteritis (AGE) is a common reason for children to receive medical care. However, the viral etiology of AGE illness is not well described in the post-rotavirus vaccine era, particularly in the outpatient (OP) setting.

METHODS

Between 2012 and 2015, children 15 days through 17 years old presenting to Vanderbilt Children's Hospital, Nashville, Tennessee, with AGE were enrolled prospectively from the inpatient, emergency department, and OP settings, and stool specimens were collected. Healthy controls (HCs) were enrolled and frequency matched for period, age group, race, and ethnicity. Stool specimens were tested by means of reverse-transcription real-time quantitative polymerase chain reaction for norovirus, sapovirus, and astrovirus RNA and by Rotaclone enzyme immunoassay for rotavirus antigen, followed by polymerase chain reaction verification of antigen detection.

RESULTS

A total of 3705 AGE case patients and 1563 HCs were enrolled, among whom 2885 case patients (78%) and 1110 HCs (71%) provided stool specimens that were tested. All 4 viruses were more frequently detected in AGE case patients than in HCs (norovirus, 22% vs 8%, respectively; rotavirus, 10% vs 1%; sapovirus, 10% vs 5%; and astrovirus, 5% vs 2%; P < .001 for each virus). In the OP setting, rates of AGE due to norovirus were higher than rate for the other 3 viruses. Children <5 years old had higher OP AGE rates than older children for all viruses.

CONCLUSIONS

Norovirus remains the most common virus detected in all settings, occurring nearly twice as frequently as the next most common pathogens, sapovirus and rotavirus. Combined, norovirus, sapovirus, rotavirus, and astrovirus were associated with almost half of all AGE visits and therefore are an important reason for children to receive medical care.

2759. Immunogenicity of Inactivated Influenza Vaccines Given Early vs. Late After Pediatric Allogeneic Hematopoietic Cell Transplantation

Background

Pediatric hematopoietic cell transplant (HCT) recipients often fail to have robust responses to influenza (flu) vaccine. We conducted a blinded phase II trial comparing high-dose (HD) trivalent inactivated vaccine (TIV) vs. standard dose (SD) quadrivalent inactivated vaccine (QIV).

Methods

Children 3–17 years old and 3–35 months post-allogeneic HCT were enrolled at 9 centers and randomized to either 2 doses of HD-TIV or SD-QIV during the 2016–2017 flu season. We compared immune responses by hemagglutination inhibition (HAI) from children 3–11 (early) vs. 12–35 (late) months (m) post-HCT to 3 common flu vaccine antigens, irrespective of vaccine type. HAI responses were evaluated at baseline (visit 1), 1 m post dose 1 (visit 2) and dose 2 (visit 3), and 7 m post dose 2 (visit 4). Geometric mean titers (GMT) were adjusted for baseline log-titer values.

Results

Thirty-one children, median age 11 (7–15) years, were enrolled; 17 (55%) were immunized early and 14 (45%) late. Over 50% of patients had a potentially seroprotective (≥1:40) HAI titer at baseline, with no significant difference post-vaccination between early and late subjects. Table 1 compares early vs late subjects with HAI seroconversion (4-fold HAI titer rise). Post dose 1, late subjects, compared with early, had higher rates of seroconversion to all influenza strains. Post dose 2, early subjects, compared with late, had increased seroconversion. Late subjects had higher GMTs for H1N1 post dose 1 and 2, H3N2 after dose 1, and strain B/VIC post dose 1 and 2 (Figure 1). Although immunogenicity waned throughout flu season, higher seroconversion rates and GMT to H3N2 and strain B/VIC were retained in late subjects.

Conclusion

Compared with subjects in early post-HCT group, late post-HCT subjects had better flu vaccine immune responses as noted by higher GMT and HAI seroconversion. However, 2 doses seemed more beneficial in the early post-HCT group. Future analyses are underway, including comparing immunogenicity of HD vs. SD flu vaccine.

Disclosures

Jennifer E. Schuster, MD, Satchel Health: Shareholder Flor M. Munoz, M.D, Biocryst: Grant/Research Support; CDC: Research Grant; Moderna: Other Financial or Material Support, Safety Monitoring Board Member/Chair; NIH: Research Grant; Novavax: Research Grant; UP to Date: Author and Editor - Royalties, Other Financial or Material Support.

1112. Detection of Enteric Viruses in Children With Acute Gastroenteritis

Background

Acute gastroenteritis (AGE) is a major cause of morbidity in children. Viral pathogens are the most common infectious agents. Differences in illness characteristics of AGE with and without virus detection are poorly defined. We compared AGE illness characteristics between children with and without any-virus detected, and with single vs. multiple viruses detected.

Methods

Children between 15 days and 17 years with AGE defined as diarrhea (>3 loose stools/24 hours) or any vomiting within 10 days duration were enrolled in Vanderbilt Children’s Hospital inpatient, ED, and outpatient settings from December 2012 to November 2015. Stool specimens were tested by RT-qPCR for norovirus, sapovirus, and astrovirus and by ELISA (VP6 antigen [Rotaclone^®]) for rotavirus.

Results

Of 3,705 children enrolled, 2,892 (78%) specimens were collected. A single virus was detected in 1,109 (38%) stools [51% norovirus, 20% rotavirus, 21% sapovirus, and 8% astrovirus], viral co-detections were found in 115 (4%) stools, and 1,665 (58%) had no detected viruses. Table 1 compares children with and without any-virus detected. Children with a single-virus detected were older than those with >1 virus detected (1.8 vs. 1.5 years [P < 0.05]) with no other significant differences.

Conclusion

Children with any-virus detected had more severe symptoms, higher MVS, and more frequently reported sick contacts compared with no-virus detected. Children with no-virus detected were more likely to present with fever and higher temperatures, which may be due to bacterial organisms. These data highlight the importance of infection-prevention precautions in the community and the need for additional testing to define the etiologic spectrum of AGE in children.

Disclosures

N. Halasa, sanofi pasteur: Investigator, Research support. GSK: Consultant, Consulting fee. Moderna: Consultant, Consulting fee.

1101. Comparison of Clinical Characteristics and Demographics of GII.4 vs. Other GII Noroviruses Associated With Sporadic Acute Gastroenteritis in Children in Nashville, TN, 2012–2015

Background

Norovirus is a leading cause of acute gastroenteritis (AGE) in all age groups. Although at least 28 different genotypes infecting humans have been reported, most outbreaks over the last 15 years have been caused by genogroup II (GII) viruses, of which GII.4 viruses have caused more than 50%. Since clinical differences between different genotypes are poorly understood, we sought to compare clinical characteristics in children infected with GII.4 and non-GII.4 viruses.

Methods

Children between 15 days and 17 years who presented with AGE defined as diarrhea (≥3 loose stools in a 24 hour period) or vomiting (≥1 episodes in a 24 hour period) within 10 days duration were recruited in outpatient, emergency, and inpatient settings in Nashville, TN, during 2012–2015. Stool specimens were tested by RT-qPCR for GI and GII norovirus. Norovirus-positive specimens were genotyped by sequencing of a partial region of the capsid gene. In this study, we excluded children infected with GI, mixed GI/GII and non-typeable GII viruses.

Results

Of 3,705 AGE subjects enrolled, 2,892 (78%) specimens were collected, 637 (22%) tested norovirus-positive (567 [89%] GII, 62 [10%] GI, and 8 [1%] mixed GI/GII). Of the 567 GII viruses, 461 (81%) were able to be genotyped and of those 238/461 (51.6%) were typed as GII.4 and 223/461 (48.3%) were typed as other GII genotypes (non-GII.4, primarily GII.3 [65/ 461, 14.1%], GII.6 [48/461, 10.4%] and GII.7 [36/461, 7.8%]). Over three AGE seasons, GII.4 represented 64/117 (54%), 79/178 (44%), and 71/166 (57%), of the GII infections, respectively. Compared with non-GII.4 subjects, GII.4 subjects were more likely to be younger (15.5 vs. 21.3 months, P < 0.01), and less likely to attend daycare (23% vs. 39%, P < 0.01). GII.4 subjects also were more likely to present with diarrhea (75% vs. 57%, P < 0.01) and had higher median modified Vesikari score (7 vs. 6, P < 0.01).

Conclusion

Children infected with GII.4 viruses were younger, less likely to attend child care, more likely to present with diarrhea, and had a more severe illness compared with those with non-GII.4 infections. These data provide important information on the genotype distribution of norovirus in children with AGE in Tennessee and highlight GII.4 as the most prevalent strain.

Disclosures

N. Halasa, sanofi pasteur: Investigator, Research support. GSK: Consultant, Consulting fee. Moderna: Consultant, Consulting fee.