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.

Influenza vaccination among household contacts of children with cystic fibrosis and healthy children.

BACKGROUND: It is recommended that household contacts of children with cystic fibrosis and household contacts of children <2 years of age receive annual influenza vaccinations. There is little information documenting whether this recommendation is being followed. METHODS: A 20-question survey was distributed to caregivers of children with cystic fibrosis and to caregivers of healthy children <17 years of age seen in a Saskatoon (Saskatchewan) tertiary care centre. Survey questions addressed the influenza vaccination status of the child and household contacts. Respondents were also asked to rate the influence of various factors on the decision to vaccinate, using a 5-point Likert scale. RESULTS: Reported vaccination rates were 21%, 25% and 7% among household contacts of children with cystic fibrosis, children <2 years of age and children ≥2 years of age, respectively. Advice from their physician, belief that they were too healthy, and inconvenient times and locations of vaccination centres were significant influences when compared among the three groups. Other main deterrents to vaccination were belief that the vaccine does not prevent influenza and belief that its side effects are greater than its benefits. CONCLUSION: By understanding motivators and barriers to vaccination among household contacts of children with cystic fibrosis, effective strategies may be implemented to improve vaccination coverage against influenza. Strong recommendations by clinicians and improved access to vaccination centres are essential components in improving influenza vaccination coverage.

HISTORIQUE: Il est recommandé d'administrer annuellement le vaccin contre l'influenza aux contacts familiaux d'enfants ayant la fibrose kystique et d'enfants de moins de deux ans. Peu d'information étaye le respect de cette recommandation. MÉTHODOLOGIE: Un sondage de 20 questions a été distribué aux personnes qui s'occupent d'enfants ayant la fibrose kystique et d'enfants en santé de moins de 17 ans vus dans un centre de soins tertiaires de Saskatoon, en Saskatchewan. Les questions du sondage portaient sur le statut de vaccination contre l'influenza de l'enfant et des contacts familiaux. Les répondants ont également été invités à classer l'influence de divers facteurs sur la décision de vacciner, selon l'échelle de cinq points de Likert. RÉSULTATS: Les taux de vaccination déclarés s'élevaient à 21 %, 25 % et 7 % chez les contacts familiaux d'enfants atteints de la fibrose kystique, les enfants de moins de deux ans et les enfants de deux ans et plus, respectivement. Les conseils du médecin, la conviction qu'ils étaient en trop bonne santé, de même que les heures d'ouverture et le lieu peu pratiques des centres de vaccination étaient des influences importantes au sein des trois groupes. Les autres principaux freins à la vaccination étaient la conviction que le vaccin ne prévient pas l'influenza et la conviction que ses effets secondaires sont plus importants que ses avantages. CONCLUSION: Si on comprend les sources de motivation et les obstacles à la vaccination des contacts familiaux d'enfants atteints de la fibrose kystique, on pourra peut-être adopter des stratégies efficaces pour améliorer la couverture vaccinale contre l'influenza. Des recom-mandations convaincues de la part des cliniciens et un meilleur accès aux centres de vaccination sont des éléments essentiels à une amélioration de la couverture vaccinale.

Emergence of sylvatic Echinococcus granulosus as a parasitic zoonosis of public health concern in an indigenous community in Canada.

Within a remote Canadian Indigenous community, at least 11* of people had antibodies against Echinococcus granulosus and E. granulosus eggs were detected in 6* of environmentally collected canine fecal samples. Dog ownership, hunting, and trapping were not risk factors for seropositivity, suggesting that people are most likely exposed to E. granulosus through indirect contact with dog feces in the environment. In this situation, human exposure could be most effectively curtailed by preventing consumption of cervid viscera by free-roaming dogs.

Invasive infections caused by haemophilus influenzae serotypes in twelve Canadian IMPACT centers, 1996-2001.

BACKGROUND: Haemophilus influenzae type b (Hib) immunization has changed the epidemiology of pediatric bacterial invasive disease. We describe the epidemiology of H. influenzae invasive infections in 12 Canadian pediatric tertiary care [Immunization Monitoring Program, ACTive (IMPACT)] centers during the era of universal immunization against this pathogen. METHODS: Children with positive cultures for H. influenzae serotypes a to f (Hia to Hif) and nontypable H. influenzae from sterile sites were identified from the laboratory records at 12 IMPACT centers from January 1, 1996 to December 31, 2001. Hospital records were retrospectively reviewed for demographic and clinical information. RESULTS: Of 166 H. influenzae cases, 58 (35%) were caused by Hib, 89 (54%) by non-b serotypes, and 19 (11%) were not serotyped. The non-b serotypes included: 25 Hia (28%), 4 Hid (4%), 2 Hie (2%), 11 Hif (12%), and 47 were nontypable isolates (53%). For patients with Hib and Hia infection, meningitis was the most common presentation, accounting for 40% and 52% respectively, whereas the most common presentation for nontypable serotypes was pneumonia, seen in 43% of cases. Epiglottitis was associated mainly with Hib. Aboriginal ethnicity was an important risk factor for Hia cases, accounting for 76% of patients with infections caused by this serotype. Mean duration of hospitalization, need for admission to a pediatric intensive care unit, and case fatality rates were similar for the cases because of Hib, Hia, Hif, and nontypable serotypes. CONCLUSIONS: In 1996-2001, two-thirds of H. influenzae invasive disease in the 12 IMPACT centers was caused by non-b serotypes, which were associated with significant morbidity and mortality.

Myeloid leukemia in Prader-Willi syndrome.

OBJECTIVE: To evaluate the frequency of cancers recorded by the Surveillance, Epidemiology, and End Results (SEER) Program in persons with Prader-Willi syndrome (PWS) METHODS: A survey was mailed in 1994 to 1852 registrants of the PWS Association (USA) inquiring about a diagnosis of any type of benign tumor or cancer (malignant tumor or leukemia). The risk of developing cancer was then estimated by comparing the observed number of cancers in the PWS population during 1975 to 1994 to the expected number in the general US population using data from the 1971-1994 SEER Cancer Statistics Review. RESULTS: Of the 1852 persons, 1160 (63%) responded, or 75% (1160/1552) of those who received the survey. The total number of observed cancer cases in the PWS study population was 8 versus 4.80 expected in the general US population (P =.1610). Three cases of myeloid leukemia were observed versus 0.075 leukemias expected (P =.0001). CONCLUSIONS: There appears to be an increased risk of myeloid leukemias, but not other cancers, among persons with PWS.