Evaluation of the New World Health Organization Case Definition of Severe Acute Respiratory Infection for Influenza Surveillance During the Peak Weeks of Two Influenza Seasons in Quebec, Canada.

During the peak of the 2012-2013 and 2014-2015 influenza seasons in Quebec, Canada, the sensitivity of the new World Health Organization (WHO) case definition of severe acute respiratory infection (SARI) in <5-year-old children was 65% for polymerase chain reaction-confirmed influenza and 79% for other respiratory viruses (ORVs), whereas its specificity and positive predictive value were approximately 2- and 4-fold lower for influenza than ORVs (25% vs 40% and 18% vs 76%, respectively). The use of the WHO SARI definition for influenza surveillance in children should be interpreted with caution according to the specific surveillance goals.

Determinants of parents' decision to vaccinate their children against rotavirus: results of a longitudinal study.

Rotavirus disease is a common cause of health care utilization and almost all children are affected by the age of 5 years. In Canada, at the time of this survey (2008-09), immunization rates for rotavirus were <20%. We assessed the determinants of a parent's acceptance to have their child immunized against rotavirus. The survey instruments were based on the Theory of Planned Behavior. Data were collected in two phases. In all, 413 and 394 parents completed the first and second interviews, respectively (retention rate 95%). Most parents (67%) intended to immunize their child against rotavirus. Factors significantly associated with parental intentions (Phase 1) were as follows: perception of the moral correctness of having their child immunized (personal normative belief) and perception that significant others will approve of the immunization behavior (subjective norm), perceived capability of having their child immunized (perceived behavioral control) and household income. At Phase 2, 165 parents (42%) reported that their child was immunized against rotavirus. The main determinant of vaccination behavior was parental intention to have their child vaccinated, whereas personal normative beliefs influenced both intention and behavior. The acceptability of the rotavirus vaccine will be higher if health promotion addresses parental knowledge, attitudes and beliefs regarding the disease and the vaccine.

Clinicians' opinions on new vaccination programs implementation.

In Canada, several new vaccines were recently approved for clinical use or are expected to be soon. Decision-makers are faced with the choice whether or not to include these vaccines in publicly funded vaccination programs. The aim of this study was to assess Canadian pediatricians' and family physicians' opinions regarding 7 new vaccines, and perceived priority for the introduction of new programs. A self-administered, anonymous, mail-based questionnaire was sent during fall 2009 to a random sample of 1182 family physicians and to all 1852 Canadian pediatricians. Responses to 8 statements regarding frequency and severity of the diseases, efficacy and safety of the vaccines as well as feasibility of immunization programs were used to calculate priority scores to rank the 7 potential new vaccination programs (calculated scores ranging from 0 to 100). Overall response rate was 43%. The majority of respondents perceived the health and economic burden of diseases prevented by the seven new vaccines as important and considered new vaccines to be safe and effective. More than 90% of physicians strongly agreed or agreed that the new vaccines would be or are currently well accepted by the public and by the health professionals who administer vaccines, except for the HPV and rotavirus vaccines (respectively 30% and 29% strongly agreed or agreed). Mean priority scores were: 77.4 out of 100 for the measles, mumps, rubella and varicella (MMRV) combined vaccine; 75.6 for the hexavalent (DTaP-IPV-Hib-HBV) vaccine; 73.1 for the new pneumococcal conjugate vaccines; 69.8 for the meningococcal ACYW135; 68.9 for the combined hepatitis A and B; 63.5 for the human papillomavirus vaccine and 56.9 for the rotavirus vaccine. Health professionals' opinion is an important element to consider in the decision-making process regarding implementation of new immunization programs. Without health professional support, the introduction of a new vaccination program may be unsuccessful. In this study, the MMRV and the hexavalent (DTaP-IPV-Hib-HBV) vaccines received the highest ratings.

Canadian paediatricians' opinions on rotavirus vaccination.

Rotavirus is the leading cause of dehydration and hospitalization due to gastroenteritis (GE) in young children. Almost all children are affected by the age of 5 years. Two safe and effective rotavirus vaccines are available for clinical use in Canada. In the context where rotavirus vaccination is recommended, but not publicly funded, we have assessed paediatricians' knowledge, attitudes and beliefs (KAB) regarding rotavirus disease and its prevention by vaccination. A self-administered anonymous questionnaire based upon the Health Belief Model and the Analytical framework for immunization programs was mailed to all 1852 Canadian paediatricians. The response rate was 50%. The majority of respondents rated consequences of rotavirus infection for young patients as moderate. Sixty-six percent considered that rotavirus disease occur frequently without vaccination and 62% estimated that the disease generates a significant economic burden. Sixty-nine percent of respondents considered rotavirus vaccines to be safe and 61%, to be effective. The reduction of severe GE cases was seen as the main benefit of rotavirus vaccination, while the risk of adverse events was the principal perceived barrier. Fifty-three percent (53%) indicated a strong intention to recommend rotavirus vaccines. In multivariate analysis, main determinant of paediatricians' intention to recommend rotavirus vaccines was the perceived health and economic burden of rotavirus diseases (partial R(2)=0.49, p<0.0001). More than half of surveyed paediatricians were willing to recommend rotavirus vaccines to their patients, but the proportion of respondents who had a strong intention to do so remains low when compared to several other new vaccines. As with other new vaccines, rotavirus vaccine uptake risks to remain low in Canada as long as it is not publicly funded.

Most ten-year-old children with negative or unknown histories of chickenpox are immune.

To evaluate the proportion of children to vaccinate against varicella in a catch-up program targeting 9- to 10-year-old children, a study was conducted among children age 10 years to assess the age-specific incidence of varicella and document the immunity against varicella in those with negative or unknown chickenpox history. Of the latter 62% were seropositive for varicella.

[Lack of conviction about vaccination in certain Quebec vaccinators]. / Manque de conviction face à la vaccination chez certains vaccinateurs québécois.

A questionnaire was mailed to all vaccinators in Quebec in 1998. The objective of this survey was to document vaccinators' attitudes, knowledge, and practices related to vaccination. Vaccinators generally believe in the security, efficacy and usefulness of vaccines given to young children. However, 41% of nurses do not fully agree with these opinions. More than 94% of pediatricians completely disagree that "certain practices (homeopathy, good eating habits and a healthy lifestyle) can eliminate the need for vaccination", compared with 85% of general practitioners and only 60% of nurses. Less than 25% of doctors recall children who are late in getting their immunizations; approximately 45% of vaccinators are in complete agreement with simultaneous injections of two vaccines; many circumstances are incorrectly seen as contra indications for vaccination. Public health authorities should target systematic interventions towards vaccinators to improve this situation and to increase nurses' conviction regarding the benefits of vaccination.

Effectiveness of a single dose of acellular pertussis vaccine to prevent pertussis in children primed with pertussis whole cell vaccine.

We estimated the protection given by one booster dose of acellular pertussis vaccine (aP) given at 18 months or before school entry to children already primed with whole cell vaccine (wP). Case-control studies were conducted in these two age groups. In children who received or were eligible to receive their 18 months booster, the risk of pertussis was 1.4 and 3.6 times higher for those with 4 and 3 wP, respectively, compared to those with 3 wP + 1 aP. In 5 and 6 yr old children, the risk of pertussis among the subjects with 5 and 4 wP, was 1.4 and 2.1 times higher respectively than in those who received 4 wP + 1 aP. A single dose of aP increased the protection against pertussis and this protection was greater than that obtained with a wP booster.

Importance of attributable risk in monitoring adverse events after immunization: hepatitis B vaccination in children.

OBJECTIVES: Most vaccine safety data present only the postvaccination incidence of all adverse events rather than an estimate of attributable risk. This study sought to illustrate the difference between the 2 estimates with data from a hepatitis B immunization program. METHODS: The incidence of health problems occurring before and after each dose of hepatitis B vaccine in a cohort of 1130 children were compared. RESULTS: Although 47.5% of all children reported an adverse event during the 4 weeks following each of the 3 doses, adverse events attributable to immunization occurred in only 10.6% of children. CONCLUSIONS: Postimmunization incidence systematically overestimates the risk of adverse events. Estimating actual attributable risk is necessary to avoid false beliefs regarding immunization.

[Impact of active research for vaccination information in children with incomplete or lost vaccination records]. / Impact d'une recherche active d'information vaccinale chez les enfants ayant un carnet de vaccination incomplet ou chez ceux qui l'ont perdu.

UNLABELLED: We estimated the accuracy of the information in the vaccination booklet of 8,457 children. The booklets were classified as complete (CC), incomplete (CI) or lost (CP). For children in the CI or CP categories, an active search was done in their providers' records and we assessed their vaccine coverage. Overall, the booklet provided accurate information for 88.6% of the 7,646 children who were vaccinated at least once. Among the 711 children in the CI category, the active search showed that 79% had received all their vaccines at age two years whereas this proportion was 59% among the 280 children in the CP category. The active search increased the vaccine coverage in the population by 4%. CONCLUSION: The majority of children in the CI or CP categories whose parents report that they received all their vaccines are in fact adequately vaccinated.

Opinions of Quebec parents and vaccinators on the usefulness of chickenpox vaccine.

BACKGROUND: A chickenpox vaccine was recently licensed in Canada. Because this vaccine has caused some controversy within the health care profession, studies among Quebec parents and vaccine providers were carried out, surveying their opinions concerning chickenpox vaccination. METHODS: Three studies among parents of preadolescents, parents of two-year-old children completely or incompletely vaccinated and vaccinators were completed. The studies asked for opinions concerning the usefulness of vaccinating children against chickenpox. RESULTS: The majority of parents of preadolescents (56%), and parents of two-year-old children completely (64%) and incompletely vaccinated (60%) favoured chickenpox vaccination. Among vaccinators, 53% of paediatricians, 37% of general practitioners and 33% of nurses considered universal vaccination of young children to be useful. A greater proportion of health care professionals were in favour of a policy of vaccinating groups at risk, such as susceptible adolescents (86%, 75% and 58%, respectively). There was a positive association between the perceived severity of chickenpox and the potential usefulness of the vaccine. CONCLUSION: Quebec parents are more favourably disposed to chickenpox vaccine than vaccine providers. In contrast, strategies targeting susceptible groups would be generally well received by health care professionals. A considerable amount of work will be needed to convince vaccinators of the benefits of a universal childhood vaccination against chickenpox.

Morbidity of pertussis in adolescents and adults.

The effect of age on the clinical presentation of pertussis was assessed in 664 adolescent and adult cases. Complications were more frequent in adults than in adolescents (28% vs. 16%). Pneumonia occurred in 2% of patients <30 years old but in 5%-9% of older patients. Urinary incontinence occurred in 34% of women >/=50 years old. Duration of cough, risk of sinusitis, and number of nights with disturbed sleep increased with smoking and asthma. The secondary attack rate in other household members >/=12 years was 11%. Pertussis in secondary case patients was less severe than in index case patients but presented with classic symptoms. The main source of infection in adolescents was schoolmates or friends; in adults it was workplace or their children. Teachers and health care workers had a greater risk of pertussis than did the general population. The burden of disease appears to increase with age, with smoking, and with asthma.

Comparative immunogenicity under field conditions of two recombinant hepatitis B vaccines in 8-10-year-old children.

The immunogenicity of two hepatitis B vaccines was compared in 8-10-year-old children immunized in a school program. One year apart, 1129 children received Engerix-B 10 microg vaccine (EB), and 1126 received Recombivax-HB 2.5 microg (RB), following the 0, 1, 6 schedule. Blood samples were collected one month after the third dose. Anti-Hbs were measured by commercial radioimmunoassay. In the EB group, 99.1% of the children seroconverted (>/=2 IU/l) compared to 99.7% in the RHB group (p=0.09). The seroprotection rate (>/=10 IU/l) was similar for both groups: 98.9% in the EB group and 99.2% in the RB group (p=0.66). However, GMCs of anti-HBs were higher in children given EB compared to those given RB (7307 vs. 3800 mIU/ml, p<0.0001). This study showed that both vaccines were highly immunogenic, in the course of a regular field immunization program. However, the difference observed in the antibody levels attained according to the vaccine may play a role in the long-term protection of these children.

Protection after two doses of measles vaccine is independent of interval between doses.

The protection provided by one or two doses of measles vaccine was compared, as was the effect of the timing of delivery of the doses on the protection provided. A total of 5542 measles cases occurred in Ontario, Canada, between January 1990 and December 1996. Three controls per case were matched for age and residence. Children who received a single dose at age 15 months and older were 5 times more likely to contract measles than were children who received two doses of vaccine after their first birthday. Among children given two doses of vaccines, the risk of measles was 3 times greater in those who had their first vaccination at age 11 months compared with children who first received vaccine after age 1 year, but the protection was independent of the interval between doses. Delaying the second dose >6 months after the first does not increase protection.

Failure of physicians to consider the diagnosis of pertussis in children.

To determine the ability of physicians to make a diagnosis of pertussis and factors associated with improved diagnosis, 8,235 children from 88 child care centers and 14 elementary schools from Quebec City, Quebec, Canada, were evaluated by using a questionnaire completed by parents and a medical record review. Children must have consulted a physician to be included in the evaluation. There were 558 children meeting the surveillance case definition and 416 meeting a modified World Health Organization case definition who consulted a physician. A diagnosis of pertussis was considered in 24%-26% of children meeting either case definition, made in 12%-14%, and reported for 6%. Pertussis diagnosis was significantly associated with having a history of pertussis exposure (P < or = .003), four pertussis-related symptoms (P < .001), and a cough for > or = 5 weeks (P < or = .05) and consulting in a hospital setting (P < or = .03). The proportion of cases of pertussis diagnosed and reported is low even when children present with classical symptoms.

Passive immunity against measles during the first 8 months of life of infants born to vaccinated mothers or to mothers who sustained measles.

Neutralizing antibody titers of 47 infants whose mothers sustained measles (measles group) and 70 whose mothers were vaccinated (vaccine group) were compared at birth, 4 and 8 months of age. All children had antibodies at birth and 88% at 4 months. At 8 months, 49% had antibodies in the measles group and 15% in the vaccine group (P < 0.001). The geometric mean titers were significantly lower in the vaccine group than in the measles group and the difference corresponded to the antibody loss occurring in only 1.5 months of life. This small difference may reflect past exposure to wild virus of many vaccinated mothers.