Waning Vaccine Immunity and Vaccination Responses in Children Treated for Acute Lymphoblastic Leukemia: A Canadian Immunization Research Network Study.

BACKGROUND: There is no uniform guideline for postchemotherapy vaccination of children with acute lymphoblastic leukemia (ALL). We evaluated waning immunity to 14 pneumococcal serotypes, pertussis toxin (PT), tetanus toxoid (TT) and varicella, and immunogenicity of postchemotherapy diphtheria, tetanus, pertussis, hepatitis B, polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) and pneumococcal vaccination among previously vaccinated children treated for ALL. METHODS: This was a multicenter trial of children with ALL enrolled 4-12 months postchemotherapy completion. Exclusion criteria included: infant ALL, relapsed ALL, and stem cell transplant recipients. Immunocompetent children were recruited as controls. Postchemotherapy participants received DTaP-IPV-Hib and 13-valent pneumococcal conjugate vaccine (PCV13) concurrently, followed by 23-valent pneumococcal polysaccharide vaccine (PPV23) 2 months later. Serology was measured at baseline, 2 and 12 months postvaccination. Adverse events were captured via surveys. RESULTS: At enrollment, postchemotherapy participants (n = 74) were less likely than controls (n = 78) to be age-appropriately immunized with DTaP (41% vs 89%, P < .001) and PCV (59% vs 79%, P = .008). Geometric mean concentrations (GMCs) to TT, PT, PCV serotypes, and varicella were lower in postchemotherapy participants than controls after adjusting for previous vaccine doses (P < .001). Two months postvaccination, GMCs to TT, PT, and PCV serotypes increased from baseline (P < .001 for all antigens) and remained elevated at 12 months postvaccination. Antibody levels to PPV23 serotypes also increased postvaccination (P < .001). No serious adverse events were reported. CONCLUSIONS: Children treated for ALL had lower antibody levels than controls against pneumococcal serotypes, tetanus, pertussis, and varicella despite previous vaccination. Postchemotherapy vaccination with DTaP-IPV-Hib, PCV13, and PPV23 was immunogenic and well tolerated. Children with ALL would benefit from systematic revaccination postchemotherapy. CLINICAL TRIALS REGISTRATION: NCT02447718.

Early-Onset Invasive Candidiasis in Extremely Low Birth Weight Infants: Perinatal Acquisition Predicts Poor Outcome.

BACKGROUND: Neonatal invasive candidiasis (IC) presenting in the first week of life is less common and less well described than later-onset IC. Risk factors, clinical features, and disease outcomes have not been studied in early-onset disease (EOD, ≤7 days) or compared to late-onset disease (LOD, >7 days). METHODS: All extremely low birth weight (ELBW, <1000 g) cases with IC and controls from a multicenter study of neonatal candidiasis enrolled from 2001 to 2003 were included in this study. Factors associated with occurrence and outcome of EOD in ELBW infants were determined. RESULTS: Forty-five ELBW infants and their 84 matched controls were included. Fourteen (31%) ELBW infants had EOD. Birth weight <750 g, gestation <25 weeks, chorioamnionitis, and vaginal delivery were all strongly associated with EOD. Infection with Candida albicans, disseminated disease, pneumonia, and cardiovascular disease were significantly more common in EOD than in LOD. The EOD case fatality rate (71%) was higher than in LOD (32%) or controls (15%) (P = .0001). The rate of neurodevelopmental impairment and mortality combined was similar in EOD (86%) and LOD (72%), but higher than in controls (32%; P = .007). CONCLUSIONS: ELBW infants with EOD have a very poor prognosis compared to those with LOD. The role of perinatal transmission in EOD is supported by its association with chorioamnionitis, vaginal delivery, and pneumonia. Dissemination and cardiovascular involvement are common, and affected infants often die. Empiric treatment should be considered for ELBW infants delivered vaginally who have pneumonia and whose mothers have chorioamnionitis or an intrauterine foreign body.

Invasive candidiasis in low birth weight preterm infants: risk factors, clinical course and outcome in a prospective multicenter study of cases and their matched controls.

BACKGROUND: This multicenter prospective study of invasive candidiasis (IC) was carried out to determine the risk factors for, incidence of, clinical and laboratory features, treatment and outcome of IC in infants of birth weight <1250 g. METHODS: Neonates <1250 g with IC and their matched controls (2:1) were followed longitudinally and descriptive analysis was performed. Survivors underwent neurodevelopmental assessment at 18 to 24 months corrected age. Neurodevelopmental impairment (NDI) was defined as blindness, deafness, moderate to severe cerebral palsy, or a score <70 on the Bayley Scales of Infant Development 2nd edition. Multivariable analyses were performed to determine risk factors for IC and predictors of mortality and NDI. RESULTS: Cumulative incidence rates of IC were 4.2%, 2.2% and 1.5% for birth-weight categories <750 g, <1000 g, <1500 g, respectively. Forty nine infants with IC and 90 controls were enrolled. Necrotizing enterocolitis (NEC) was the only independent risk factor for IC (p=0.03). CNS candidiasis occurred in 50% of evaluated infants, while congenital candidiasis occurred in 31%. Infants with CNS candidiasis had a higher mortality rate (57%) and incidence of deafness (50%) than the overall cohort of infants with IC. NDI (56% vs. 33%; p=0.017) and death (45% vs. 7%; p=0.0001) were more likely in cases than in controls, respectively. IC survivors were more likely to be deaf (28% vs. 7%; p=0.01). IC independently predicted mortality (p=0.0004) and NDI (p=0.018). CONCLUSION: IC occurred in 1.5% of VLBW infants. Preceding NEC increased the risk of developing IC. CNS candidiasis is under-investigated and difficult to diagnose, but portends a very poor outcome. Mortality, deafness and NDI were independently significantly increased in infants with IC compared to matched controls.

Impact of the COVID-19 pandemic on healthcare-associated viral respiratory infections at a tertiary care pediatric hospital.

The incidence of healthcare-associated viral respiratory infections in a pediatric hospital decreased from 1.6 /1,000 patient-days in 2019 to 0.2 /1,000 patient-days in 2020 (P < .01), and this was maintained in 2021 despite an increase in community circulation of respiratory viruses. Universal masking, stricter infection control measures, and pandemic public health interventions likely accounted for this improvement.

Characteristics and outcome of infants with candiduria in neonatal intensive care - a Paediatric Investigators Collaborative Network on Infections in Canada (PICNIC) study.

BACKGROUND: There is limited information in the literature on the presentation and prognosis of candidal urinary tract infection (UTI) in infants in the neonatal intensive care unit (NICU). METHODS: This was a prospective cohort study performed in 13 Canadian NICUs. Infants with candidal UTI without extra-renal candidal infection at presentation were enrolled. RESULTS: Thirty infants fit the study criteria. Median birth weight and gestational age were 2595 grams (range 575-4255) and 35 weeks (range 24-41) with 10 infants being < 30 weeks gestation. The most common primary underlying diagnosis was congenital heart disease (n = 10). The median age at initial diagnosis was 16 days (range 6-84 days). Renal ultrasonography findings were compatible with possible fungal disease in 15 of the 26 infants (58%) in whom it was performed. Treatment was variable, but fluconazole and either amphotericin B deoxycholate or lipid-based amphotericin B in combination or sequentially were used most frequently. Extra-renal candidiasis subsequently developed in 4 infants. In 2 of these 4 infants, dissemination happened during prolonged courses of anti-fungal therapy. Three of 9 deaths were considered to be related to candidal infection. No recurrences of candiduria or episodes of invasive candidiasis following treatment were documented. CONCLUSION: Candidal UTI in the NICU population occurs both in term infants with congenital abnormalities and in preterm infants, and is associated with renal parenchymal disease and extra-renal dissemination. A wide variation in clinical approach was documented in this multicenter study. The overall mortality rate in these infants was significant (30%). In one third of the deaths, Candida infection was deemed to be a contributing factor, suggesting the need for antifungal therapy with repeat evaluation for dissemination in infants who are slow to respond to therapy.

Prevention of laboratory-acquired brucellosis.

Brucellosis is one of the most common laboratory-acquired infections, mostly because aerosolization is a mechanism of transmission in this setting. We report an exposure to Brucella melitensis that occurred in a large microbiology laboratory and describe the strategy chosen for antibiotic prophylaxis and serological follow-up of exposed workers.

Clinical aspects and cost of invasive Streptococcus pneumoniae infections in children: resistant vs. susceptible strains.

Invasive Streptococcus pneumoniae infections in children are associated with serious consequences in terms of morbidity and mortality. The main objective of the study was to determine if invasive infections caused by penicillin-resistant Streptococcus pneumoniae (PRSP) differed in clinical presentation, outcome, risk factors, or cost from those caused by penicillin-susceptible strains (PSSP) in children. All patients aged 18 or less with invasive Streptococcus pneumoniae infections admitted to two teaching hospitals in Montreal between 1989 and 1998 were included in the study. We present a case-control study in which for each index case of PRSP, 3 controls with PSSP infections were matched for age, sex, and site of infection. One hundred and forty-four patients were included in the analysis (36 cases, 108 controls). There was no difference between the two groups in terms of initial clinical presentation (vital signs, laboratory results) or total length of stay. Mortality was 2.7% in both groups. Hospital antibiotic cost was higher in the PRSP group (211 Canadian dollars (CAD) vs. 74 CAD; P=0.02). Antibiotic consumption in the preceding month was significantly associated with PRSP infection. Underlying diseases or day-care attendance were not shown to be significant risk factors for acquiring invasive PRSP infection. There were no differences between invasive infections caused by PRSP and PSSP in terms of clinical presentation, morbidity or mortality in a paediatric population.

Safety and immunogenicity of a toddler dose following an infant series of a hexavalent diphtheria, tetanus, acellular pertussis, inactivated poliovirus, Haemophilus influenzae type b, hepatitis B vaccine administered concurrently or at separate visits with a heptavalent pneumococcal conjugate vaccine.

BACKGROUND: Combination diphtheria-tetanus-5 component acellular pertussis-inactivated poliovirus-Haemophilus influenzae b conjugate-hepatitis B vaccine (DTaP5-IPV-Hib-HepB) administered either concurrently with 7-valent pneumococcal conjugate vaccine (PCV7) or 1 month apart was generally safe and immunogenic at 2, 4 and 6 months of age. This study examined the effects of a booster dose at age 15 months. METHODS: Participants were randomized to DTaP5-IPV-Hib-HepB plus PCV7, DTaP5-IPV-Hib-HepB with PCV7 administered 1 month later or a pentavalent DTaP5-IPV/Hib plus HepB plus PCV7 at 15 months of age in a randomized, open-label, phase IIb clinical trial. Immunogenicity endpoints were rates of seroresponse to pertussis toxoid, filamentous hemagglutinin, pertactin and fimbriae types 2 and 3; rates of seroprotection against (Hib) polyribosylribitol phosphate capsular polysaccharide, hepatitis B surface antigen, diphtheria toxoid, tetanus toxoid and poliovirus types 1, 2 and 3; and geometric mean titers to all vaccine antigens. Safety endpoints included solicited injection-site reactions and systemic and serious adverse events. RESULTS: Seroresponse/seroprotection rates for all antigens exceeded prespecified criteria in both groups that received the hexavalent DTaP5-IPV-Hib-HepB; in the group that received the currently licensed pentavalent vaccine, seroresponse/seroprotection rates exceeded the criteria for all antigens except filamentous hemagglutinin. Seroresponse rates were ≥88.9% for pertussis antigens and seroprotection rates against polyribosylribitol phosphate capsular polysaccharide, hepatitis B surface antigen, diphtheria toxoid, tetanus toxoid and poliovirus antigens were ≥95.1% in recipients of DTaP5-IPV-Hib-HepB. CONCLUSIONS: DTaP5-IPV-Hib-HepB administered concomitantly with PCV7 or 1 month apart at 15 months of age following the infant series was well-tolerated and elicited antibody responses to all vaccine antigens, with no significant interference from concomitant PCV7 administration (clinicaltrials.gov registration number NCT00362427).

Safety and immunogenicity of a hexavalent vaccine administered at 2, 4 and 6 months of age with or without a heptavalent pneumococcal conjugate vaccine: a randomized, open-label study.

BACKGROUND: DTaP5-IPV-Hib-HepB, an investigational hexavalent combination vaccine, was evaluated for safety and immunogenicity, when administered to infants with heptavalent pneumococcal conjugate vaccine (PCV7). METHODS: Infants were randomized to receive DTaP5-IPV-Hib-HepB plus PCV7, DTaP5-IPV-Hib-HepB with PCV7 administered 1 month later or DTaP5-IPV/Hib plus HepB plus PCV7 at 2, 4 and 6 months of age in an open-label, phase IIb trial. Vaccine responses were assessed by pertussis toxoid, filamentous hemagglutinin, pertactin and fimbriae types 2/3 seroconversion rates, Haemophilus influenzae type b polyribosylribitol phosphate capsular polysaccharide, hepatitis B surface antigen, diphtheria toxoid, tetanus toxoid and poliovirus types 1, 2 and 3 seroprotection rates and geometric mean titers. Solicited injection site and systemic reactions, serious adverse events, and other safety outcomes were reported. RESULTS: Seroprotection rates to polyribosylribitol phosphate, hepatitis B surface antigen, diphtheria toxoid, tetanus toxoid and poliovirus antigens across all groups met or exceeded predetermined acceptability criteria. Seroconversion rates to pertussis toxoid, pertactin and fimbriae types 2/3, but not filamentous hemagglutinin, met such criteria. Antidiphtheria antibodies were significantly lower when PCV7 was coadministered. Geometric mean titers to the other antigens of the hexavalent and PCV7 vaccines were all high and similar in the 2 groups. No safety signals were noted. CONCLUSIONS: DTaP5-IPV-Hib-HepB administered at 2, 4 and 6 months of age concomitantly with PCV7 was well tolerated and elicited robust antibody responses to all but the antidiphtheria antigens for which there may be evidence of immune interference. Only filamentous hemagglutinin did not meet seroconversion rate acceptability criteria.

Safety and immunogenicity of 2 mixed primary infant immunization schedules of pentavalent diphtheria, tetanus, acellular pertussis, inactivated poliomyelitis, and Haemophilus influenzae Type B vaccines at 2, 4, and 6 months of age: a randomized controlled trial.

BACKGROUND: Two pentavalent infant vaccines that contain either 5 or 3 component acellular pertussis antigens are authorized in Canada. Because of changes in vaccine use by provinces over time and movement of families across jurisdictions, it is possible that children are exposed to different combination vaccines during the primary infant immunization schedule. The safety and immunogenicity of mixed primary infant schedules is unknown. METHODS: In a double-blind multicenter trial, 2-month-old healthy infants were randomized to 1 of 2 schedules at 2, 4, and 6 months of age (either Pediacel, Pediacel, Infanrix [PPI] or Infanrix, Pediacel, Pediacel [IPP]). Solicited local and systemic adverse events (AEs) were collected by parent diary on days 0 through 7; unsolicited AEs were collected for 31 days after each dose. Immune responses to polypolyribosylribitol phosphate capsular polysaccharide (PRP) (Haemophilus influenzae type b) and pertussis antigens were assessed before the first dose and 28 days after the 6 month (third) dose. RESULTS: In all, 127 infants were randomized to IPP and 126 to PPI. The percentage of children with anti-PRP responses ≥0.15 µg/mL after dose 3 was higher in the IPP than in the PPI group (98.3, 95% CI: 94.1, 99.8 vs. 86.1%, 95% CI: 78.6, 91.7, P < 0.001). Antipertussis toxin and anti-fimbriae 2 and 3 responses were statistically significantly higher in the IPP than in the PPI group. Higher filamentous hemagglutinin responses occurred in PPI than in IPP. No difference between groups was observed in pertactin responses.Systemic AEs were similar between the 2 vaccine schedules. Irritability (67.2 vs. 51.6, P = 0.014) and mild crying (35.2% vs. 23.0%, P = 0.037) were more common after the 6-month dose in the PPI compared with the IPP group, as were overall systemic reactions (any intensity) for the PPI group after this dose (80.0 vs. 68.0, P = 0.042). CONCLUSION: Mixed 2-, 4-, 6-month pentavalent infant vaccine schedules had different immunogenicity and reactogenicity, with a PPI schedule being more reactogenic, and less immunogenic for PRP and fimbriae 2 and 3 antigens at 7 months. It is preferable to complete the primary infant 3-dose vaccine series with the same vaccine, rather than considering infant vaccines as interchangeable.

QuickVue influenza test for rapid detection of influenza A and B viruses in a pediatric population.

The performance of a lateral-flow immunoassay, the QuickVue Influenza Test, for detection of influenza A and B viruses in comparison with that of cell culture was evaluated by using nasopharyngeal aspirates, in viral transport medium, from children with respiratory tract infections. The sensitivity and specificity were 79.2 and 82.6%, respectively.