Parental perceptions of childhood seasonal influenza vaccination in Singapore: A cross-sectional survey

PurposeSeasonal influenza vaccination is recommended in children aged 6–59 months, but little is known about child vaccination coverage and determinants in Asian settings. We report the results of a survey of knowledge, attitudes, practices, and determinants of child influenza vaccination in Singapore.MethodsIn December 2015-March 2016, we conducted a survey of 332 parents of children aged 6 months to 5 years attending pre-schools. We assessed child influenza vaccine coverage and parental knowledge, attitudes, and practices of child influenza vaccination. We used multivariable regression and structural equation models to identify factors associated with child influenza vaccination.ResultsKnowledge about influenza, perceived benefit of vaccination, and willingness to vaccinate were high. However, only 32% of children had ever received influenza vaccine, and only 15% in the past year. Factors independently associated with child influenza vaccination included: being recommended influenza vaccine by a child’s doctor (prevalence ratio (PR) = 2.47, 95% CI: 1.75–3.48); receiving influenza vaccine information from a private general practitioner (PR = 1.47, 95% CI: 1.05–2.04); regularly receiving pre-travel influenza vaccine (PR = 1.64, 95% CI: 1.19–2.25); higher willingness to vaccinate (PR = 1.58, 95% CI:1.24–2.04 per unit increase in willingness score); and feeling well-informed about influenza vaccine (PR = 1.44, 95% CI: 1.04–1.99). Parents who obtained influenza vaccine information from television were less likely to have vaccinated their child (PR = 0.44, 95% CI: 0.23–0.85). Path analysis indicated that being recommended vaccination by a child's doctor increased willingness to vaccinate and self-efficacy (feeling well-informed about influenza vaccine). Median willingness-to-pay for a dose of influenza vaccine was SGD30 (interquartile range: SGD20-SGD50), and was higher in parents of vaccinated compared with unvaccinated children (SGD45 vs SGD30, p = 0.0012).ConclusionKnowledge and willingness to vaccinate was high in this parent population, but influenza vaccine uptake in children was low. Encouraging medical professionals to recommend vaccination of eligible children is key to improving uptake.     

Parents’ views on the acceptability of a COVID-19 vaccine for their children: A cross-sectional study in Abu Dhabi-United Arab Emirates

BackgroundThe United Arab Emirates had approved the COVID-19 vaccine for children. Assessing parents’ acceptance of the vaccine for their children will influence decision-making in the COVID-19 vaccine roll-out.MethodParents registered in the Abu Dhabi Department of Education (12,000 families) were invited to complete an online questionnaire from 8th September 2021 to 17th October 2021. Out of the 12,000 families, 2510 (21%) participants answered the survey. The questionnaire investigated the parents’ attitudes and beliefs regarding the COVID-19 vaccine.ResultsThe vaccination rate among this group of respondents was high, with 2255 (89.9%) having received two doses and 1002 (45.5%) having already received a booster dose. Acceptance of the respondents to vaccinate their children was high, (75.1%) said they would vaccinate their children, with 64.4% reporting that they would immediately vaccinate their children if the vaccine were made available. Determinants of COVID-19 child vaccination acceptance included the respondent’s vaccination status—i.e., if the respondent is already vaccinated (OR 4.96 [2.89–8.53]) or has taken the third dose (OR 2.37 [1.4–4.01])—their children’s age (OR 1.11 [1.30–1.18] for older children), and their trust in the following information sources: the government (OR 2.53 [1.61–3.98]), health care providers (OR 1.98 [1.2–3.24]), or social media (OR 2.17 [1.22–3.88]). Increased level of education had a negative impact on the acceptance of giving the vaccine to children (OR 0.63 [0.52–0.77]); fear of side effects OR 0.000164 (0.000039–0.001) was another determinant. The main factor that encouraged parents to give their children the vaccine was to protect their child’s health as reported by 1537 (55.5%) participants.ConclusionThe Abu Dhabi community is highly accepting of the vaccine for their children. Future studies of how this vaccine acceptance can influence the pandemic are needed.     

HPV vaccination and risk of chronic fatigue syndrome/myalgic encephalomyelitis: A nationwide register-based study from Norway

BackgroundVaccination has been suggested to be involved in the aetiology of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). HPV vaccine was introduced in the Norwegian Childhood Immunisation Programme and offered 12 year old girls from 2009. We studied the association between HPV vaccination and risk of CFS/ME and also assessed medical history in relation to both risk of CFS/ME and HPV vaccine uptake.MethodsIndividual data from national registries, including the Norwegian Population Registry, the Norwegian Patient Registry and the Norwegian Immunisation Registry were linked using the unique personal identification number. Yearly incidence rates of CFS/ME for 2009–2014 were calculated among the 824,133 boys and girls, aged 10–17 living in Norway during these 6 years. A total of 176,453 girls born 1997–2002 were eligible for HPV vaccination and included in further analyses. Hazard ratios (HRs) of CFS/ME were estimated using Cox regression. Risk differences (RDs) of vaccine uptake were estimated with binomial regression.ResultsA similar yearly increase in incidence rate of CFS/ME was observed among girls and boys, IRR = 1.15 (95% confidence interval (CI) 1.10–1.19) and 1.15 (95% CI 1.09–1.22), respectively. HPV vaccination was not associated with CFS/ME, HR = 0.86 (95% CI 0.69–1.08) for the entire follow-up period and 0.96 (95% CI 0.64–1.43) for the first two years after vaccination. The risk of CFS/ME increased with increasing number of previous hospital contacts, HR = 5.23 (95% CI 3.66–7.49) for 7 or more contacts as compared to no contacts. Girls with 7 or more hospital contacts were less likely to be vaccinated than girls with no previous hospital contacts, RD = −5.5% (95% CI −6.7% to −4.2%).ConclusionsNo indication of increased risk of CFS/ME following HPV vaccination was observed among girls in the first 6 birth cohorts offered HPV vaccine through the national immunisation programme in Norway.     

What predicts postpartum pertussis booster vaccination? A controlled intervention trial

Background‘Cocooning’ aims to protect susceptible infants from pertussis via caregiver vaccination. Control trials evaluating educational interventions to promote cocooning are lacking. We evaluated the role of message-framing vs. standard health information in promoting pertussis vaccination.MethodsWe recruited postpartum women from a maternity hospital in Sydney, Australia (November 2010–July 2012). Participants self-completed a pertussis knowledge and attitudes questionnaire. We then assigned pertussis-susceptible (no pertussis vaccine ≤10 years) participants to receive a gain-framed, loss-framed pamphlet or control (Government Pertussis factsheet) using weekly sequential block allocation. Next, participants were offered a pertussis vaccine (dTpa) and completed a post-questionnaire on discharge.ResultsA baseline questionnaire was completed for 96.4% (1433/1486) of postpartum women approached. Missing data was excluded (n = 29). Next, participants (1404) were screened for vaccine status: 324 (23%) reported prior pertussis booster vaccine receipt, leaving 1080 participants requiring vaccination. Among susceptible mothers, 70% (754/1080) were vaccinated post-intervention. Rates were similar between ‘gain’, ‘loss’ or ‘control’ pamphlets (69.1% vs. 71.8% vs. 68.8%; p = 0.62). Intention to be vaccinated (OR 2.46, p < 0.001; 95% CI: 1.69–3.58), perceived vaccine benefits (OR: 1.61, p < 0.001; 95% CI: 1.25–2.15) and having received a vaccine recommendation (OR 1.68; p = 0.025; 95% CI: 1.07–2.65) were independent predictors of vaccine uptake. At discharge, overall pertussis vaccine coverage had increased from 23% to 77% among women screened (1078/1404).ConclusionA cocooning strategy for pertussis vaccination can be highly effective when partially implemented within maternity hospitals, with information accompanied by a funded vaccine. Mothers were highly receptive to vaccination in the postnatal ward: facts about pertussis were as effective as message-framing in promoting a high uptake of 70%. Perceived vaccine benefits, intentions and vaccine recommendation were important predictors of uptake. Our intervention trial increased the existing pertussis vaccine coverage of 23–77%.     

Low tetanus,diphtheria and acellular pertussis (Tdap) vaccination coverage among HIV infected individuals in Austria

Current management guidelines of HIV infected adults include recommendation to immunization against common vaccine preventable diseases. This effort is hindered by the scarce knowledge regarding the immunization status of this especially vulnerable patient group. This study analyzed the serostatus for pertussis, diphtheria and tetanus of more than 700 HIV infected individuals residing in Austria. These individuals were representative for the Austrian HIV cohort regarding sex, age, transmission risk and HIV progression markers. Overall, 73.6% were on suppressive HAART, mean CD4 cell count was 603 c/μl. Seropositivity was 84% for diphtheria, 51% for tetanus and 1% for pertussis. Migrants had a lower chance of tetanus seropositivity (OR 0.30 (CI 0.21 to 0.43)). Increase in CDC classification were associated with increased diphtheria seropositivity (OR 1.42 (CI 1.02 to 1.98)) and a CD4 nadir < 200 c/μl was associated with increased pertussis seropositivity (OR 12.2, 95% CI 1.2 to 121). Importantly due to the well preserved immune status of nearly all participants vaccination would be feasible in the majority of the seronegative patients. In patients with a CD4 count > 200 c/μl, 95% lacked seroprotection to at least one of the antigens included in the triple vaccine Tdap and could be vaccinated. Thus, a proactive approach would largely reduce the number of patients at risk for these vaccine-preventable diseases.     

Predictors of optional immunization uptake in an urban south Indian population

BackgroundIn Tamil Nadu, India, bacille Calmette–Guérin, diphtheria–tetanus–pertussis, oral poliomyelitis, hepatitis B, and measles vaccines are part of the routine immunization schedule and are available free from government health centers. All other vaccines are optional and available in the private sector at a cost to families. This study assesses immunization rates of routine and optional vaccines and examines parental attitudes toward vaccines in Pallavapuram, Tamil Nadu.MethodsThe cluster sampling method was used to estimate immunization coverage. Seven children 18 to 36 months old were selected from 30 clusters for a total sample of 210 children. Demographics and vaccination data were collected from interviews and immunization records. Predictors of vaccination status were identified with logistic regression models. In addition, 21 parents participated in semi-structured interviews regarding their attitudes toward vaccination. Interviews were analyzed qualitatively for themes.ResultsEighty one percent of children were fully immunized with routine vaccines. However, only 21% received all “major” optional vaccines, defined as 3 doses of Haemophilus influenzae type b vaccine, one dose of measles, mumps, rubella vaccine, and one dose of varicella zoster virus vaccine. Birth in a private hospital (OR 5.6, 95% CI 1.3 to 22.9, P < 0.01), higher income (P = 0.03), and maternal completion of high school (OR 6.4, 95% CI 1.5 to 27.6, P < 0.01) were significant predictors of receiving all major optional vaccines. Elucidated themes from interviews included (1) strong parental support for immunizations, (2) low concern for side effects, and (3) low uptake of optional vaccines due to high cost and lack of awareness.ConclusionsCoverage of optional vaccines is low despite positive attitudes toward immunizations. Efforts to reduce cost and increase awareness of these vaccines particularly among low-income families or to include these vaccines in the routine schedule may increase uptake and reduce morbidity and mortality from vaccine-preventable diseases.     

Safety of the 2011–12, 2012–13, and 2013–14 seasonal influenza vaccines in pregnancy: Preterm delivery and specific malformations,a study from the case-control arm of VAMPSS

BackgroundPregnant women have higher risks of influenza complications, but vaccine coverage is incomplete. Because concern about fetal harm limits uptake, we investigated risks for preterm delivery (PTD) and specific birth defects following vaccination in the 2011–12 through 2013–14 influenza seasons.MethodsWe used data from the Slone Epidemiology Center’s Birth Defects Study. For PTD, propensity score-adjusted time-varying hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for exposure anytime in pregnancy and for each trimester. For 42 specific major birth defects or birth defect categories, propensity score-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated.ResultsFor PTD (1803 fullterm deliveries, 107 PTD for all seasons combined), an elevated adjusted risk was observed for only the 2nd trimester of the 2011–12 season (HR = 2.60, 95% CI 1.21, 5.61) – a reduction in gestational length of <2 days. For the 42 specific defects or categories of defects (2866 cases, 1411 controls for all seasons combined) most adjusted risks were close to 1.0; the highest was 2.38 for omphalocele and the lowest was 0.50 for atrioventricular canal defects. None had lower confidence bounds >1.0. For each season separately, only one elevated OR had a lower 95% CI >1.0: omphalocele in 2011–12 (OR = 5.19, 95% CI 1.44, 18.7).ConclusionsOur results regarding risks for PTD and birth defects are generally reassuring. The few risks that were observed are compatible with chance, but warrant testing in other data. Given that vaccine components and manufacturing processes vary, continuing studies are needed to evaluate risks and safety of each season’s vaccine and specific products.     

Risk factors of ICU or high dependency requirements amongst hospitalized pediatric pertussis cases: A 10 year retrospective series,Singapore

IntroductionPertussis causes the highest complication rates and deaths in the infant group. Our study explored risk factors for ICU/high dependency (HD) admissions and intubation/non-invasive ventilation (NIV).MethodsA retrospective review of pertussis admissions over 10 years from 2007 to 2016 was done at KK Women's and Children's Hospital, Singapore. To understand risk factors for severe pertussis infection, we compared cases requiring ICU/HD care with controls admitted to the general ward. Risk factors for intubation/NIV were also studied. Vaccine efficacy for protection against ICU/HD admission or intubation/NIV was also calculated.ResultsThere were 200 pertussis patients with a median age of 2.75 months. Sixty-one % were ≤3 months and 14.5% were <6 weeks old. Majority of patients (77%) had no prior pertussis vaccination. After removing 3 patients with missing vaccination records, 20 cases were compared with 177 controls. On univariate analysis, risk factors for ICU/HD admission comprised: Age ≤3 months, contact history, underlying co-morbidity, prematurity, absent DTaP vaccination, lymphocytosis, hyperleukocytosis (wbc ≥50 × 10⁹/L), thrombocytosis (platelet ≥500 × 10⁹/L), and pneumonia. Multivariate analysis revealed that age ≤3 months (OR 40, 95% CI 4.57–1111.11, p = .007), co-morbidity (OR 8.46 (95% CI 1.47–56.89, p = .019), pneumonia (OR 18.08, 95% CI 3.22–132.15, p = .002), white cell count (OR 1.07, 95% CI 1.01–1.14, p = .023) and cyanosis (OR 5.09, 95% CI 1.31–24.71, p = .026) were risk factors for ICU/HD admission. Prior DTaP vaccination had a vaccine effectiveness of 86.5% in preventing ICU/HD admission and 82.1% in preventing intubation/NIV.ConclusionsAs the majority of pertussis patients were infants ≤3 months old who are at high risk for ICU/HD admission and intubation/NIV, prevention is key to reducing pertussis morbidity. Even though not statistically significant, DTaP vaccination had a role in preventing ICU/HD admission and intubation/NIV.     

Comparing the rubella seronegativity in pregnant women who received one dose of rubella vaccine at different ages in Taiwan

IntroductionVaccination is the best strategy to prevent rubella and congenital rubella. The aim of our study was to assess the immunity to rubella and determine rubella virus antibody titers in pregnant women who were offered a single dose of rubella vaccine at different ages of their lives.MethodsA total 15,067 rubella IgG antibody test results for Taiwanese pregnant women who received routine prenatal checkup at Fooyin University Hospital from 1999 to 2014 were analyzed in this study. The women were divided into five birth cohorts in order to compare their rubella seronegativities and antibody titers according to the different period of rubella vaccination policy in Taiwan.ResultsThe total rubella seronegativity rate was 11.2% (95% CI: 10.7–11.7%) and the mean rubella antibody titers was 51.0 IU/mL (SD = 54.7 IU/mL). The junior school cohort has the lowest rubella seronegativity of 7.6% (95% CI: 6.9–8.2%). The seronegativities were significantly high in the preschool cohort and in the 15-month-old cohort, 14.9% (95% CI: 13.2–16.6%) and 14.8% (95% CI: 11.5–18.1%), respectively. The OR values were 2.1 (95% CI: 1.8–2.5, p < 0.001) in the preschool cohort and 2.2 (95% CI: 1.6–2.8, p < 0.001) in the 15-month-old cohort, respectively, against the junior school cohort. Women in the 15-month-old cohort have lowest average rubella IgG titer, 25.4 IU/mL.ConclusionThe total rubella seronegativity rate was 11.2% in all native pregnant women. Women who received one dose rubella vaccine at preschool and 15-month-old have highest seronegativities. The 15-month-old cohort has the lowest average rubella IgG titer. We recommend a revised catch-up immunization policy to women who received one dose rubella vaccine at a younger age.     

Association of both consistency and strength of self-reported clinician recommendation for HPV vaccination and HPV vaccine uptake among 11- to 12-year-old children

PurposeWe tested the hypotheses that consistency and strength of clinician recommendation of the human papillomavirus (HPV) vaccination would be associated with vaccine delivery rates.MethodsFrom October 2015 through January 2016, we conducted a survey of primary care clinicians (n = 227) in Southeastern Minnesota to evaluate clinician behaviors regarding HPV vaccination. The survey response rate was 41.0% (51 clinical sites). We used the Rochester Epidemiology Project, a clinical data linkage infrastructure, to ascertain clinical site-level HPV vaccination rates. We examined associations of clinician self-reports of both the consistency and strength of their recommendations for HPV vaccination for patients aged 11–12 years (n = 14,406) with site-level vaccination rates.ResultsThe majority of clinicians reported consistently (always or usually) recommending the HPV vaccine to females (79.0%) and to males (62.2%); 71.9% of clinicians reported strongly recommending the vaccine to females while 58.6% reported strongly recommending to males. Consistency and strength of recommending the HPV vaccine was significantly higher among those practicing in pediatrics and board certified in pediatrics compared to family medicine. Higher rates of initiation (1 dose) [Incidence Rate Ratio (IRR) = 1.05; 95% CI (1.01–1.09)] and completion (3 doses) [IRR = 1.08; 95% CI (1.02–1.13)] were observed among clinical sites where, on average, clinicians more frequently reported always or usually recommending the vaccine for females compared to sites where, on average, clinicians reported recommending the vaccine less frequently. Similarly, higher rates of initiation [IRR = 1.03; 95% CI (1.00–1.06)] and completion [IRR = 1.04; CI (1.00, 1.08)] were observed among sites where clinicians reported strongly recommending the vaccine to females more frequently compared to sites where, on average, clinicians reported strongly recommending the HPV vaccine less frequently; similar associations were observed for male initiation [IRR = 1.05; CI (1.02,1.08)] and completion [IRR = 1.05; 95% CI (1.01, 1.09)].ConclusionsConsistency and strength of HPV vaccination recommendation was associated with higher vaccination rates.     

Effectiveness of acellular pertussis vaccine in a routine immunization program: A multicenter,case-control study in Japan

In 2008, the number of pertussis cases increased substantially among Japanese adolescents, despite high coverage with acellular pertussis vaccine (DTaP). This study examined the effectiveness of DTaP vaccine in the routine immunization program in Japan. Between April 2009 and October 2012, we conducted a multicenter, case-control study, and compared the history of DTaP vaccination between 55 newly diagnosed pertussis cases and 90 age- and sex-matched controls. DTaP vaccine history was obtained by a self-administered questionnaire completed by their parents or guardians. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) of vaccination for development of pertussis.DTaP vaccination of ≥1 dose revealed a significantly lower OR for pertussis (OR = 0.20, 95%CI, 0.04–0.97), and the OR of complete vaccination (4 doses) was 0.22 (0.04–1.05). Even after limiting subjects to those whose vaccination status could be confirmed by the immunization records, the negative associations were observed. The decreasing ORs of 4-dose vaccinees remained, even among subjects who had received the fourth dose ≥9.2 years earlier (OR = 0.11, 95%CI, 0.01–1.02).In conclusion, DTaP vaccination had a preventive effect for pertussis. Effectiveness was observed even 9 or more years after the final dose.     

Influenza during pregnancy: Incidence,vaccination coverage and attitudes toward vaccination in the French web-based cohort G-GrippeNet

IntroductionPregnancy is a risk factor for severe influenza. However, data on influenza incidence during pregnancy are scarce. Likewise, no data are available on influenza vaccine coverage in France since national recommendation in 2012. We aimed to assess these points using a novel nationwide web-based surveillance system, G-GrippeNet.MethodsDuring the 2014/2015 influenza season, pregnant women living in metropolitan France were enrolled through a web platform (https://www.grippenet.fr/). Throughout the season, participants were asked to report, on a weekly basis, if they had experienced symptoms of influenza-like-illness (ILI). ILI episodes reported were used to calculate incidence density rates based on period of participation from each participant. Vaccination coverage was estimated after weighing on age and education level from national data on pregnant women. Factors associated with higher vaccination coverage were obtained through a logistic regression with Odds Ratio (OR) corrected with the Zhang and Yu method.ResultsA total of 153 women were enrolled. ILI incidence density rate was 1.8 per 100 person-week (95%CI, 1.5–2.1). This rate was higher in women older than 40 years (RR = 3.0, 95%CI [1.1–8.3], p = 0.03) and during first/second trimesters compared to third trimester (RR = 4.0, 95%CI [1.4–12.0], p = 0.01). Crude vaccination coverage was 39% (95%CI, 31–47) and weighted vaccination coverage was estimated at 26% (95%CI, 20–34). Health care provider recommendation for vaccination (corrected OR = 7.8; 95%CI [3.0–17.1]) and non-smoking status (cOR = 2.1; 95%CI [1.2–6.9]) were associated with higher vaccine uptake.ConclusionThis original web based longitudinal surveillance study design proved feasible in pregnant women population. First results are of interest and underline that public health policies should emphasize the vaccination promotion through health care providers.     

Tetanus,diphtheria, and acellular pertussis vaccination during pregnancy and reduced risk of infant acute respiratory infections

BackgroundTo protect infants from pertussis infection, the Advisory Committee on Immunization Practices (ACIP) recommends women receive the tetanus toxoid, reduced diphtheria toxoid, acellular pertussis (Tdap) vaccine between 27 and 36 weeks of pregnancy. Here, we assessed the association between timing of maternal Tdap vaccination during pregnancy and acute respiratory infection (ARI) in infants <2 months of age.MethodsThis retrospective cohort study included 99,434 infants born to active duty military women in the Department of Defense Birth and Infant Health Registry from 2006 through 2013. Multivariable log-binomial regression was used to calculate relative risks (RRs) and 95% confidence intervals (CIs) for the association between maternal Tdap vaccination during pregnancy and infant ARI at <2 months of age.ResultsInfants of mothers who received Tdap vaccination during pregnancy vs those who did not were 9% less likely to be diagnosed with an ARI at <2 months of age (RR, 0.91; 95% CI, 0.84–0.99), and the risk was 17% lower if vaccination was received between 27 and 36 weeks of pregnancy (RR, 0.83; 95% CI, 0.74–0.93). Similar results were observed when comparing mothers who received Tdap vaccination prior to pregnancy in addition to Tdap vaccination between 27 and 36 weeks of pregnancy versus mothers who only received vaccination prior to pregnancy (RR, 0.85; 95% CI, 0.74–0.98).ConclusionsMaternal Tdap vaccination between 27 and 36 weeks of pregnancy was consistently protective against infant ARI in the first 2 months of life vs no vaccination during pregnancy, regardless of Tdap vaccination prior to pregnancy. Our findings strongly support current ACIP guidelines recommending Tdap vaccination in late pregnancy for every pregnancy.     

Seroprevalence of anti-HBs antibodies at young adulthood,before and after a booster vaccine dose,among medical personnel vaccinated in infancy

BackgroundQuestions remain regarding the long-term protection provided by childhood HBV vaccination. The goals of this study were to assess HBV seroprevalence among medical personnel purportedly vaccinated in infancy; to investigate the immune response after a booster dose given in young adulthood; and to identify predictors of non-responders.MethodsBetween 2011 and 2013 we studied Israeli male military recruits purportedly vaccinated in infancy. All subjects were born after January 1st 1992 and were undergoing medic training. We collected personal data and blood samples at baseline, and administered a dose of HBV vaccine. Subjects were retested one month later and received a second dose. A third blood draw was conducted one month after the second dose. Data collected at baseline were used as predictor variables of seropositivity (anti-HBs ≥ 10 mIU/ml).Results617 subjects were available for baseline analysis and 539 for paired observations at one month. Baseline seropositivity was 33.7%. Subjects who received post-infancy vaccine doses had a seropositivity rate double that of those denying additional doses (RR 2.22, 95% CI 1.55–3.18). One month after the first booster dose, the overall cumulative population seropositivity reached 87.7%. One month after the second vaccine dose, population seropositivity was 97.9%. Heavy smokers were 5 times less likely to demonstrate detectable antibodies after a single booster dose (OR 0.196, 95% CI 0.060–0.641, P = 0.007).ConclusionsThis population-based study is important for informing public health vaccination policy. Our results strongly indicate that among cohorts vaccinated in infancy, two doses in adulthood will provide maximal protective antibody levels, while one dose will provide sufficient population protection.     

Travel medicine consultation: An opportunity to improve coverage for routine vaccinations

BackgroundTravelers may be responsible for the spread of vaccine-preventable diseases upon return. Travel physicians and family physicians may play a role in checking and updating vaccinations before traveling. Our aim was to evaluate the vaccine coverage for mandatory and recommended vaccination in travelers attending a travel medicine clinic (TMC).MethodsVaccine coverage was measured using the current French immunization schedule as reference for correct immunization, in travelers providing a vaccination certificate during the TMC visit (university hospital of Saint-Étienne), between August 1, 2013 and July 31, 2014.ResultsIn total, 2336 travelers came to the TMC during the study period. Among the 2019 study participants, only 1216 (60.3%) provided a vaccination certificate. Travelers who provided a vaccination certificate were significantly younger than travelers who did not (mean age: 34.8 ± 17.8 vs. 46 ± 18.4 years, P < 0.005) and were less likely to be Hajj pilgrims. Vaccine coverage against Tetanus, Diphtheria, and Poliomyelitis (Td/IPV vaccine) was 91.8%, 78.6% against Measles, Mumps, and Rubella (MMR), and 59.4% against Viral Hepatitis B (HBV). BCG vaccine coverage was 71.9%. Older travelers were less likely to be correctly vaccinated, except against HBV as vaccinated travelers were significantly older than unvaccinated travelers.ConclusionObtaining information about immunization in travelers is difficult. Coverage for routine vaccines should be improved in this population. Travel medicine consultations could be the opportunity to vaccinate against MMR, HBV, and Td/IPV.     

Determinants of under-immunization and cumulative time spent under-immunized in a Quebec cohort

BackgroundUnder-immunization refers to a state of sub-optimal protection against vaccine preventable diseases. Vaccine coverage for age may not capture intentional or non-intentional spacing of vaccines in the recommended provincial immunization guidelines. We aimed to identify factors associated with coverage and under-immunization and to determine the number of days during which children were under-immunized during their first 24 months of life.MethodsSecondary analysis of children ≤3 years recruited through active surveillance for gastroenteritis from three Quebec pediatric emergency departments from 2012 to 2014. Vaccination status for children at least 24 months of age was determined using provincial immunization guidelines. Cumulative days under-immunized were calculated for DTaP-VPI-Hib, PCV, MMR, and Men-C-C. Factors associated with up-to-date (UTD) status at 24 months of life and for under-immunization ≥6 months were analyzed using logistic regression.ResultsOf 246 eligible children, 180 (73%) were UTD by 24 months of life. The mean cumulative days under-immunized for MMR was 107 days, for PCV 209 days, for Men-C-C 145 days, and for DTaP-VPI-Hib 227 days. Overall, 149 children (60%) experienced delay for at least 1 vaccine. Factors associated with both an UTD status at 24 months and concurrently associated with being under-immunization ≥6 months, included timely initiation of immunization (OR = 5.85; 95% CI: 2.80–12.22) and (OR = 0.13; 95% CI: 0.07–0.24), failure to co-administer 18-month vaccines (OR = 0.15; 95% CI: 0.10–0.21) and (OR = 3.29; 95% CI: 2.47–4.39), and having a household with ≥3 children under 18 years ((OR = 0.50; 0.28–0.86) and (OR = 2.99; 1.45–6.22), respectively.ConclusionPaired with an unexpected low level of coverage at 24 months of life, the majority of our cohort also experienced a state of under-immunization for a least one vaccine. Estimates of coverage do not capture intentional or non-intentional gaps in protection from vaccine preventable illnesses. Timely preventive care should be prioritized.     

Assessment of preparation time with fully-liquid versus non-fully liquid paediatric hexavalent vaccines. A time and motion study

Background and aimsSimplified vaccine preparation steps would save time and reduce potential immunisation errors. The aim of the study was to assess vaccine preparation time with fully-liquid hexavalent vaccine (DTaP-IPV-HB-PRP-T, Sanofi Pasteur MSD) versus non-fully liquid hexavalent vaccine that needs reconstitution (DTPa-HBV-IPV/Hib, GlaxoSmithKline Biologicals).MethodsNinety-six Health Care Professionals (HCPs) participated in a randomised, cross-over, open-label, time and motion study in Belgium (2014). HCPs prepared each vaccine in a cross-over manner with a wash-out period of 3–5 min. An independent nurse assessed preparation time and immunisation errors by systematic review of the videos. HCPs satisfaction and preference were evaluated by a self-administered questionnaire.ResultsAverage preparation time was 36 s for the fully-liquid vaccine and 70.5 s for the non-fully liquid vaccine. The time saved using the fully-liquid vaccine was 34.5 s (p ≤ 0.001). On 192 preparations, 57 immunisation errors occurred: 47 in the non-fully liquid vaccine group (including one missing reconstitution of Hib component), 10 in the fully-liquid vaccine group. 71.9% of HCPs were very or somewhat satisfied with the ease of handling of both vaccines; 66.7% and 67.7% were very or somewhat satisfied with speed of preparation in the fully-liquid vaccine and the non-fully liquid vaccine groups, respectively. Almost all HCPs (97.6%) stated they would prefer the use of the fully-liquid vaccine in their daily practice.ConclusionsPreparation of a fully-liquid hexavalent vaccine can be completed in half the time necessary to prepare a non-fully liquid vaccine. The simplicity of the fully-liquid hexavalent vaccine preparation helps optimise reduction of immunisation errors.     

Seroprevalence of antibodies against serogroup C meningococci in the region of Valencia,Spain: Impact of meningococcal C conjugate vaccination

Background and aimsMeningococcal C conjugate (MCC) vaccination programs provide direct and indirect protection against meningococcal disease. However, a decrease in the antibodies could affect herd immunity. We conducted a seroprevalence study to assess the immunity in subjects 8–12 years after different MCCV vaccination programs were launched and evaluated the impact of vaccination on seroprotection.MethodsSeroepidemiological study conducted from October 2010 to April 2012 in the region of Valencia, Spain. Sample size was not proportional to the population but to the expected seroprotection by age group. Sera from subjects that were ≥ 3 years old were tested using a standardized complement-mediated serum bactericidal antibodies (SBA) assay. Age-stratified proportions of subjects with SBA titers ≥ 8 were considered seroprotected and evaluated. A multivariate logistic regression model was performed to evaluate the impact of vaccination on the seroprotection.ResultsSerum samples from 1880 subjects were collected. In total, 523 (27.8%) of the 1880 subjects and 446 (31.2%) of the 1430 subjects < 30 years (targeted to any vaccination campaign) showed protective SBA titers. The highest percentage of seroprotected subjects (67.8%, 95%CI 56.9–77.4) was observed in those that were vaccinated in a catch-up campaign at 10–13 years of age (20–21 years old at the time of blood sampling). Those scheduled for immunization in infancy at 2, 4 and 6 months of age (7–8 years at blood sample) represented the lowest (7.1%, 95% CI 3.3–13.1) number of seroprotected subjects. Having received one vaccine dose after 12 months of age was associated with increased seroprotection. The present study revealed a positive correlation between the increasing age at vaccination and longer duration of seroprotection.ConclusionOnly one in three subjects who were vaccinated with MCC vaccine was seroprotected after 8–12 years. These findings emphasize that seroprevalence studies are essential to identify susceptible cohorts and to inform vaccine policy.