A retrospective nationwide register-based study to evaluate the non-specific effects of first MMR vaccination among children in Finland

BackgroundAccording to earlier studies, live vaccines like measles-mumps-rubella (MMR) vaccine could reduce also other infections than only the infections they are targeted against. This non-specific effect has been seen especially in studies in low-income countries and results from high-income countries have not been unambiguous. In 2011 Finland changed the recommended schedule for the first MMR vaccination from 18 months to 12 months of age. This change created a natural experiment for evaluating the potential non-specific effects.MethodsThis is a retrospective nationwide register-based cohort study of Finnish children born between 2008 and 2012. Children were divided into two cohorts by age at MMR vaccination: children administered early MMR vaccination (11 through 12 months of age) and late MMR vaccination (18 through 19 months of age). Morbidity was evaluated during the main follow-up period (from 13 to 17 months of age) and before any MMR vaccination (3 to 10 months) and after all were vaccinated with MMR (20 to 35 months) as control follow-up periods. We analyzed all infections and did additional analyzes for urinary tract infections (UTI) and bronchitis. Injuries were analyzed as a control outcome.ResultsEarly MMR vaccinated children (N = 79 949) had fewer infections compared to late MMR vaccinated (N = 60 965) during the main follow-up period. The incidence rate ratio (IRR) was 0.84 (95 % confidence interval (95 % CI) 0.81–0.87). However, similar differences were also observed during the control follow-up periods. MMR vaccinated children had less UTI in the main follow-up period (IRR 0.73, 0.60–0.89) but not in the control follow-up periods. When stratified by sex, the difference was observed among girls but not in boys.ConclusionNo clear evidence was found for non-specific effects in infectious diseases morbidity. However, there could be a nonspecific effect on UTI. Confirmation is needed from other studies, especially from high-income countries.     

Simultaneous vaccination with MMR and DTaP-IPV-Hib and rate of hospital admissions with any infections: A nationwide register based cohort study

BackgroundIn Denmark, live measles, mumps, and rubella vaccine (MMR) is associated with a reduced risk of infectious disease admissions, particularly for lower respiratory tract infections. In low-income countries, simultaneous vaccination (i.e. vaccination at the same visit) with live and inactivated vaccines may increase child mortality compared with the live vaccine alone. We examined the hypothesis that simultaneous administration of MMR and the inactivated DTaP-IPV-Hib vaccine compared with MMR alone is associated with higher incidence of infectious disease admissions.MethodsNationwide, retrospective, register based cohort study of 520,859 children born in Denmark 1997–2006, who were followed from 15 months to 4 years of age. Incidence rate ratios (IRRs) of hospital admissions were estimated by Cox regression and adjusted for background factors including exact age.ResultsBy 2 years of age, 4965 children had simultaneous MMR and DTaP-IPV-Hib as their most recent vaccination. Compared with MMR alone, simultaneous administration was associated with a higher rate of lower respiratory tract infections (adjusted incidence rate ratio (IRR), 1.27; 95% confidence interval (CI), 1.13–1.42). There was no effect on other infections. Overall, simultaneous administration was associated with a 7% (95% CI, 0–15%) increase in infectious disease admissions.ConclusionsSimultaneous administration of MMR and DTaP-IPV-Hib compared with MMR alone may increase the rate of hospital admissions related to lower respiratory tract infections. These findings require replication in other high-income settings.     

Long-term surveillance of rotavirus vaccination after implementation of a national immunization program in Finland (2008–2018)

BackgroundRotavirus (RV) vaccination was included in the Finnish National immunization Program (NIP) in 2009. RotaTeq (RV5) has been used exclusively with a national average vaccination coverage rate (VCR) of > 90%. While previous studies have demonstrated that inpatient rotavirus gastroenteritis (RVGE) admissions declined by as much as 96% in Finnish children ≤ 5 years old following RV vaccination introduction, no study has evaluated long-term protection after vaccination in Finland. In this study, we analyze incidence of hospital outpatient visits and inpatient admissions of gastroenteritis in children up to 7 years of age.MethodsWe first describe the incidence of RVGE, viral gastroenteritis (VGE), and acute gastroenteritis (AGE) for all Finnish children born during 2008–2011. Children were stratified by the year of birth into not-eligible, partially eligible and rotavirus vaccine-eligible (born in 2008, 2009, 2010 and 2011, respectively). Hospital inpatient and outpatient data was collected from the National Care Register for all children from birth until December 31st, 2018. We also studied RVGE incidence during 2014–2017 for children<3 years of age in municipalities with VCRs of 90% and above and municipalities with VCRs below 90%.ResultsRVGE incidence decreased significantly soon after implementation of RV vaccination in the NIP. In vaccine-eligible cohorts, no clear peak incidence in the youngest age groups could be observed, and no RVGE cases were observed beyond 6 years after vaccination, in contrast to vaccine ineligible and partially eligible cohorts. Despite an overall high VCR in Finland, regions with high VCR had lower incidence of RVGE than regions with lower VCR.ConclusionIncidence of RVGE has remained low in all age groups during the 10 years following introduction of RV vaccine in the Finnish NIP. Differences in RVGE incidence were observed in regions with high as compared with lower VCR, highlighting the importance of maintaining high vaccination coverage.     

Socioeconomic factors influencing childhood vaccination in two northern Italian regions

BackgroundInfant vaccination rates have been declining in Italy over the past 5–7 years. The aims of this study were to assess the trend in the proportions of children unvaccinated at 24 months old, to identify sociodemographic factors associated with non-vaccination; and to examine changes in parental attitudes to vaccination over time.MethodsWe conducted a population-based birth cohort study by combining existing electronic data sets. The study population consisted of children born from 1995 to 2010 in the Friuli-Venezia Giulia (FVG) region, and from 2007 to 2011 in part of the Emilia Romagna (ER) region, in north-eastern Italy. The immunization registers were linked with the medical birth registers, which contain sociodemographic data on both parents and the newborn. Unconditional logistic regressions were used to identify associations between vaccine uptake at 24 months and maternal sociodemographic variables.ResultsOf 145,571 babies born in FVG and 75,308 in ER, there were 4222 (1.9%) who had not been vaccinated at all, and 23,948 (11.0%) without the optional measles, mumps and rubella (MMR) vaccination. The number of unvaccinated infants increased over time. Mothers who were over 35 or under 25 years old, unmarried, with a higher formal education, and citizens of highly-developed countries were less compliant with vaccination recommendations in both the regions. A cohort effect was observed in FVG, for both educational level and citizenship: babies born between 1995 and 2000 to mothers without an Italian citizenship and with a lower formal education were more likely to refuse vaccination for their offspring, while this association was reversed between 2006 and 2010.ConclusionsMothers who are Italian citizens and have a good formal education have begun to refuse vaccination for their children in recent years. Future public health action in this setting should target highly educated parents.     

Determinants of Bacillus Calmette–Guérin (BCG) vaccination among Québec children

ObjectivesTo identify determinants of Bacillus Calmette–Guérin (BCG) vaccination among children born in Québec, Canada, in 1974, the last year of the systematic vaccination campaign.MethodA retrospective birth cohort was assembled in 2011 through probabilistic linkage of administrative databases (n = 81,496). Potential determinants were documented from administrative databases and by interviewing a subset of subjects (n = 1643) in 2012. Analyses were conducted among subjects with complete data, 71,658 (88%) birth cohort subjects and 1154 (70%) interviewed subjects, then redone using multiple imputation. Determinants of BCG vaccination during the organized vaccination program (in 1974), and after the program (1975 onwards) were assessed separately. Logistic regression with backward elimination was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).ResultsOverall, 46% of subjects were BCG vaccinated, 43% during the program and 4% after it ended. BCG vaccination during the program was associated with parents' birthplace and urban or rural residence. BCG vaccination after the organized program was only related to ethnocultural origin of the child's grandparents.ConclusionDifferent factors were related to vaccination within and after the organized program. Determinants of BCG vaccination in Québec, Canada, have never been studied and will be useful for future research and vaccination campaigns.     

Public health impact of Rotarix vaccination among commercially insured children in the United States

BackgroundThis study (NCT01915888) assessed public health impact of Rotarix, GSK [RV1] vaccination.MethodsChildren born between 2007–2011 were identified from Truven Commercial Claims and Encounters Databases and observed until earlier of plan disenrollment or five years old. Children receiving one or two doses of RV1 during the vaccination window were assigned to incomplete and complete vaccination cohorts, respectively. Children without rotavirus (RV) vaccination (RV1 OR RotaTeq, Merck & Co., Inc. [RV5]) were assigned to the unvaccinated cohort. Claims with International Classification of Disease 9th edition (ICD-9) codes for diarrhea and RV infections were identified. First RV episode incidence, RV-related and diarrhea-related healthcare resource utilization were compared. Multivariate Poisson regression with generalized estimating equations was used to generate 95% confidence intervals (CIs) around incidence rate ratios (IRR) between cohorts while adjusting for gender, age and calendar year. Mean costs for first RV and diarrhea episodes were calculated with adjustment for gender and birth year; bootstrapping was used to determine statistically significant differences between cohorts.ResultsIncidence of first RV episodes was significantly reduced in complete and incomplete vaccination cohorts compared to the unvaccinated cohort (IRR = 0.17 [95%CI: 0.09–0.30] and IRR = 0.19 [95%CI: 0.06–0.58], respectively). RV-related inpatient, outpatient and emergency room (ER) visits were significantly lower for complete vaccination versus unvaccinated cohort. Diarrhea-related inpatient and ER visit rates were significantly lower for complete vaccination versus unvaccinated cohorts; outpatient rates were similar. RV-related and diarrhea-related resource utilization rates were significantly lower or no different for incomplete vaccination versus unvaccinated cohort. Compared with unvaccinated children, adjusted mean cost for first RV episode and first diarrhea episode per 1000 persons was $11,511 (95%CI: $9855-$12,024) and $46,772 (95%CI: $26,268-$66,604) lower, respectively, for completely vaccinated children.ConclusionsRV1 vaccination confers benefits in reduction of RV incidence, RV- and diarrhea-related healthcare resource utilization, and RV- and diarrhea-related healthcare costs.     

Bacille Calmette-Guérin (BCG) vaccination at birth and antibody responses to childhood vaccines. A randomised clinical trial

IntroductionBCG vaccination has been associated with beneficial non-specific effects on child health. Some immunological studies have reported heterologous effects of vaccines on antibody responses to heterologous vaccines. Within a randomised clinical trial of Bacille Calmette-Guérin (BCG) vaccination at birth, The Danish Calmette Study, we investigated the effect of BCG at birth on the antibody response to the three routine vaccines against DiTeKiPol/Act-Hib and Prevenar 13 in a subgroup of participants.MethodsWithin 7 days after birth, children were randomised 1:1 to BCG vaccination or to the control group (no intervention). After three routine vaccinations given at age 3, 5 and 12 months, antibodies against DiTeKiPol/Act-Hib and Prevenar 13 (Streptococcus pneumoniae serotype type 4, 6B, 9V, 14, 18C, 19F and 23F) were measured 4 weeks after the third vaccine dose.ResultsAmong the 300 included children (178 BCG; 122 controls), almost all children (>96%) had antibody responses above the protective levels. Overall BCG vaccination at birth did not affect the antibody level. When stratifying by ‘age at randomisation' we found a possible inducing effect of BCG on antibodies against B. pertussis and all pneumococcal serotypes, when BCG was given after the first day of life. Girls had significantly higher antibody levels for Haemophilus influenza type b and pneumococcus than boys.Conclusions and relevanceThree routine vaccinations with DiTeKiPol/Act-Hib and Prevenar 13 induced sero-protective levels in almost all children. No overall effect of neonatal BCG vaccination was observed.     

Longitudinal,population-based cohort study of prenatal influenza vaccination and influenza infection in childhood

BackgroundInfluenza vaccination is recommended to protect mothers and their infants from influenza infection. Few studies have evaluated the health impacts of in utero exposure to influenza vaccine among children more than six months of age.MethodsWe used probabilistically linked administrative health records to establish a mother–child cohort to evaluate the risk of influenza and acute respiratory infections associated with maternal influenza vaccination. Outcomes were laboratory-confirmed influenza (LCI) and hospitalization for influenza or acute respiratory infection (ARI). Adjusted hazard ratios (aHRs) accounted for child’s Aboriginal status and were weighted by the inverse-probability of treatment.Results14,396 (11.5%) children were born to vaccinated mothers. Maternally vaccinated infants aged < 6 months had lower risk of LCI (aHR: 0.33; 95% CI: 0.13, 0.85), influenza-associated hospitalization (aHR: 0.39; 95% CI: 0.16, 0.94) and ARI-associated hospitalization (aHR: 0.85; 95% CI: 0.77, 0.94) compared to maternally unvaccinated infants. With the exception of an increased risk of LCI among children aged 6 months to < 2 years old following first trimester vaccination (aHR: 2.28; 95% CI: 1.41, 3.69), there were no other differences in the risk of LCI, influenza-associated hospitalization or ARI-associated hospitalization among children aged > 6 months.ConclusionStudy results show that maternal influenza vaccination is effective in preventing influenza in the first six months and had no impact on respiratory infections after two years of age.     

Characteristics and incidence of vaccine adverse events after Bacille Calmette–Guérin vaccination: A national surveillance study in Japan from 2013 to 2017

BackgroundJapan amended the recommended age for the Bacille Calmette–Guérin (BCG) vaccination to less than 6 months after 2005, but subsequently amended the recommended age to 5–8 months (latest amendment, <1 year) in April 2013 due to the increasing incidence of BCG-associated osteitis/osteomyelitis since 2005.MethodsWe collected data on BCG-associated vaccine adverse events (VAEs) in the population aged <1 year between April 2013 and March 2017. The incidence of BCG-associated VAE was analyzed using census and vaccine coverage data from the government website. We compared the incidence of VAEs in patients vaccinated at less than 6 months with those vaccinated at 6 months or older.ResultsAmong the 581 BCG-associated VAEs recorded during the study period, 354 (61%) were male, and the average age at vaccination was 5.7 months. The incidence of VAEs per million population aged <1 year at vaccination was highest for suppurative lymphadenitis (63.7), followed by skin lesions (38.4), and BCG-associated osteitis/osteomyelitis (3.1). Disseminated BCG and anaphylaxis were rare (1.1 and 1.6%, respectively). The incidence of VAEs in the population vaccinated at <6 months of age was higher for BCG-associated osteitis/osteomyelitis (3.8) and disseminated BCG (1.3) than in the population vaccinated at ≥6 months.ConclusionsThe population vaccinated at <6 months of age was more likely to develop BCG-associated osteitis/osteomyelitis than the population vaccinated at ≥6 months of age, indicating that the change in the recommended vaccination age in 2013 might have contributed to the subsequent decrease in the incidence of BCG-associated osteitis/osteomyelitis.     

Community cohort study of Cryptosporidium parvum infections: sex-differential incidences associated with BCG and diphtheria-tetanus-pertussis vaccinations

OBJECTIVE: Community studies in West Africa have suggested that routine vaccinations may have sex-differential non-targeted effects, the female-male mortality ratios being increased after receiving diphtheria-tetanus-pertussis (DTP) vaccination and reduced after administration of BCG or measles vaccine (MV). Using an existing data set, we examined whether vaccinations were associated with gender-differential incidences of Cryptosporidium parvum infection. METHODS: Two hundred children had been recruited shortly after birth and followed until 2 years of age or until follow-up was interrupted by a war. We performed weekly morbidity interviews and collected stool specimens, irrespective of whether the children had diarrhoea. Vaccination status for each child was classified according to the most recent vaccination with BCG, DTP, or MV. FINDINGS: The female-male incidence rate ratio (IRR) for Cryptosporidium infection among children who had received BCG as their last vaccine was 0.0 (95% CI: 0-3.49). However, among those who had received DTP as their last vaccine, the female-male IRR was 6.25 (2.06-18.9) for Cryptosporidium infection and 3.60 (0.91-14.2) for Cryptosporidium-associated diarrhoea. The female-male IRRs for Cryptosporidium infection differed significantly among BCG and DTP recipients (p=0.01). Among children who had received measles as their last routine vaccine, the female-male IRR was 1.57 (0.60-4.11) for Cryptosporidium infection and 0.98 (0.28-3.52) for Cryptosporidium-associated diarrhoea. The female-male IRRs for Cryptosporidium infection differed among DTP and MV recipients (p=0.02). For girls, early DTP vaccination compared with late or no DTP vaccination was associated with increased incidence rate of Cryptosporidium infection (IRR=4.23 (1.04-17.2)). For girls, the incidence rate decreased when they received MV. INTERPRETATION: Routine immunisations may affect morbidity for non-targeted infections. As in studies of infant mortality, BCG is associated with a low risk for girls relative to boys, whereas DTP is associated with a high female-male IRR of C. parvum infection.     

Measles–mumps–rubella vaccination and respiratory syncytial virus-associated hospital contact

BackgroundThe live measles vaccine has been associated with lower non-measles mortality and admissions in low-income countries. The live measles–mumps–rubella vaccine has also been associated with lower rate of admissions with any type of infection in Danish children; the association was strongest for admissions with lower respiratory infections.ObjectiveTo examine whether measles, mumps, and rubella (MMR) vaccination was associated with reduced rate of hospital contact related to respiratory syncytial virus (RSV) in a high-income country.MethodsNationwide cohort study of laboratory-confirmed RSV hospital contacts at age 14–23 months in all children born in Denmark 1997–2002 who had already received the vaccine against diphtheria, tetanus, pertussis (acellular), polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) at the recommended ages of 3, 5, and 12 months.ResultsThe study included 888 RSV hospital contacts in 128,588 person years of follow up (rate 6.8/1000 person years). Having MMR as the most recent vaccine was associated with a reduced rate of RSV hospital contacts compared with having DTaP-IPV-Hib as the most recent vaccine (Incidence rate ratio (IRR), 0.75; 95% confidence interval (CI), 0.63–0.89). After adjustment for potential confounders including exact age in days the IRR was 0.78 (95% CI, 0.66–0.93). The adjusted IRR was 0.74 (95% CI, 0.60–0.92) in males and 0.84 (95% CI, 0.66–1.06) in females (P Interaction, 0.42). There was no association in the first month after MMR vaccination (adjusted IRR, 0.97; 95% CI, 0.76–1.24) but the adjusted IRR was 0.70 (95% CI, 0.58–0.85) from one month after MMR vaccination.ConclusionsMMR vaccination was associated with reduced rate of hospital contacts related to laboratory-confirmed RSV infection. Further research on the association between MMR vaccination and other unrelated pathogens are warranted.     

Disseminated BCG infection: a four case study

BCG inoculation at birth has been compulsory in our country since 1959. Adverse reactions induced by BCG vaccination are rare, ranging from zero to 23.8%. Disseminated infections are even rarer and their estimated incidence is 0.1 to 4.3 per one million vaccinated children. Lethal disseminated BCG infection is exceptional and affects especially the children presenting an immune deficiency. A familial gene defect may play a role. BCG osteitis is second to suppurative lymphadenitis in clinical forms; it generally develops five months to five years after vaccination. We report four cases of disseminated BCG infection occuring in children from three months to four years of age, leading to death in two cases. Our objective is to discuss the pathologic aspects of BCG infection.     

Impact and effectiveness of the 10-valent pneumococcal conjugate vaccine on invasive pneumococcal disease among children under 5 years of age in the Netherlands

BackgroundIn 2011, the 7-valent pneumococcal conjugate vaccine (PCV7) was replaced by the 10-valent vaccine (PCV10) in the Netherlands. We report on impact and effectiveness against invasive pneumococcal disease (IPD) in children aged under 5 years by switching from PCV7 to PCV10.MethodWe included IPD cases between 2004 and 2019 in children aged < 5 years reported via the national surveillance system. To assess the impact of the PCV10 vaccination program we compared IPD incidence 6-8 years after PCV10 introduction (2017–2019) to the two years just before the switch to PCV10 (2009–2011). We estimated vaccine effectiveness (VE) using the indirect cohort method, comparing vaccination status (at least two vaccine doses) in IPD-cases caused by PCV10 serotypes (cases) to non-PCV10 IPD cases (controls), in children eligible for PCV10.ResultsThe overall incidence decreased from 8.7 (n = 162) in 2009–2011 to 7.3 per 100.000 (n = 127) in 2017–2019 (Incidence rate ratio (IRR) 0.83, 95%CI: 0.66; 1.05). IPD caused by the additional serotypes included in PCV10 declined by 93% (IRR 0.07, 95%CI: 0.02; 0.23). Incidence of non-PCV10 IPD showed a non-significant increase (IRR 1.25, 95%CI: 0.96; 1.63). Among 231 IPD-cases eligible for PCV10, the overall VE was 91% (95%CI: 67; 97) and did not differ by sex or age at diagnosis. Effectiveness against non-PCV10 serotype 19A IPD was non-significant with an estimate of 28% (95%CI:-179; 81).ConclusionPCV10 is highly effective in protecting against IPD in Dutch children under 5 years with limited serotype replacement after switching from PCV7 to PCV10. We found no evidence for significant cross-protection of PCV10 against 19A serotype IPD.     

The association between parental and neonatal BCG vaccination and neonatal T helper 17 cell expansion

BackgroundBacille Calmette-Guérin (BCG) vaccination reduces the severity of neonatal infections; this effect appears enhanced if the mother has received BCG. We performed immunophenotyping of the T-cell subset and characterized T-cell proliferation responses to assess possible immune response pathways.MethodsHealthy BCG-vaccinated (n = 8) and unvaccinated (n = 9) neonates born by elective caesarean section were sampled 3 weeks after birth. We compared a wide panel of intracellular cytokine and cell surface expression markers as well as proliferation response in T-cells between BCG-vaccinated and unvaccinated neonates, stratified by parental BCG status.ResultsFor all BCG-vaccinated neonates and 3 of 9 unvaccinated neonates that served as controls, both parents had a BCG scar. Th17 (CD4 + IL-17+) prevalence as percentage of total CD4 + T-cells was expanded 4-fold in BCG-vaccinated compared to unvaccinated, being 11.6% [3.6–19.6%] vs 2.8% [1.0–6.6%]. Th17 counts for 3 unvaccinated neonates born to BCG-vaccinated parents was comparable to vaccinated neonates, and higher than remaining controls, parental BCG = 8.5% [4.4–8.9%] vs 1.8% [0.8–3.3%] for no parental BCG (median [interquartile range] for all data).ConclusionAmong neonates born to BCG-vaccinated parents, the prevalence of Th17 cells, important in the response against bacterial infections, was substantially elevated. The interaction between neonatal and parental BCG for Th17 responses and the importance remains to be further investigated.     

Community cohort study of rotavirus and other enteropathogens: are routine vaccinations associated with sex-differential incidence rates?

OBJECTIVE: Community studies in West Africa have demonstrated that routine vaccinations may have non-targeted effects, the female-male mortality ratio being reduced after administration of BCG and increased after diphtheria-tetanus-pertussis (DTP). We examined whether immunisation status was associated with infection with rotavirus and other enteropathogens. METHODS: We recruited 200 children shortly after birth and followed them until 2 years of age with weekly morbidity interviews and stool sampling. Vaccination status for each child was classified according to the most recent vaccination as documented by vaccination card. MAIN OUTCOME MEASURES: The female-male incidence rate ratios (IRR) of infection with an enteropathogen and of enteropathogen-associated diarrhoea were estimated for children according to whether they had received BCG or DTP as their last vaccination. RESULTS: For children who received BCG as their last vaccine, the adjusted female-male IRRs for primary rotavirus-infection and diarrhoea were 1.05 (95% CI: 0.21-5.28) and 0.0 (95% CI: 0-3.02), respectively. For children who received DTP as their last vaccine, the adjusted female-male IRRs were 1.93 (0.89-4.21) and 1.92 (0.70-5.32), respectively, for rotavirus-associated infection and diarrhoea. Restricted to the rotavirus season, the female-male IRRs for rotavirus infection and diarrhoea were 2.56 (1.17-5.63) and 2.63 (0.94-7.34), respectively. The female-male IRR for rotavirus-associated diarrhoea differed significantly among BCG and DTP recipients (p=0.02). Infections with enteropathogens not associated with diarrhoea were associated with lower female-male IRRs after BCG of 0.82 (0.55-1.23) and higher female-male IRRs after DTP vaccination of 1.32 (1.03-1.70) for primary infection (p=0.05). Though there were few infections with other diarrhoea-causing enteropathogens, these were also associated with a lower female-male IRR after BCG of 0.62 (0.26-1.52) and a higher female-male IRR after DTP vaccination of 1.51 (1.04-2.20) for all infection. CONCLUSION: Routine immunisations may affect morbidity for non-targeted infections. As in studies of infant mortality, BCG is associated with lower risk for girls, whereas, DTP is associated with higher risk for girls relative to boys.     

Levels of antibodies specific to diphtheria toxoid,tetanus toxoid,and Haemophilus influenzae type b in healthy children born to Tdap-vaccinated mothers

IntroductionVaccination of pregnant women protects both women and their newborns against some infectious diseases. Thailand implemented tetanus toxoid (TT) vaccination of pregnant women in 1977, which was replaced by tetanus–diphtheria toxoid (dT) vaccination in 2005. The tetanus–diphtheria–acellular pertussis (Tdap) vaccine has been recommended for pregnant women at 27–36 weeks of gestation since 2012 in several countries. Data on antibody responses to diphtheria toxoid (DT), TT, and Hemophilus influenzae type b (Hib) induced by combined vaccines in children born to TT-vaccinated and/or Tdap-vaccinated mothers are limited.Material and methodsWe investigated anti-DT, anti-TT, and anti-Hib IgG responses in a cohort of Thai children (ClinicalTrial.gov NCT02408926) born to mothers who received a TT-containing and/or the Tdap vaccine during pregnancy. Children born to Tdap-vaccinated mothers were randomized to receive either a hexavalent (Infanrix-hexa) or pentavalent (Quinvaxem) vaccine, whereas children born to TT-vaccinated mothers received only Quinvaxem vaccine at 2, 4, 6, and 18 months of age. IgG levels were evaluated at birth (cord blood), 2 (pre-primary), 7 (post-primary), 18 (pre-booster), and 19 months of age (post-booster) using a commercially available enzyme-linked immunoassay.ResultsSeroprotective concentrations of anti-DT, anti-TT, and anti-Hib IgG were achieved in >90% and >99% of children following primary and booster vaccination, respectively. Among children born to Tdap-vaccinated mothers, the pentavalent vaccine induced higher levels of anti-Hib IgG than the hexavalent vaccine after primary and booster vaccination. Significantly higher anti-Hib IgG levels were observed among children receiving the pentavalent vaccine and who were born to TT-vaccinated mothers than among children receiving the pentavalent vaccine and born to Tdap-vaccinated mothers after primary and booster vaccination.ConclusionsVaccination with a TT-containing and/or the Tdap vaccine during pregnancy did not compromise the seroprotection rate achieved following primary and booster immunization in individuals receiving either the pentavalent or hexavalent vaccine.     

Incidence of pediatric inflammatory bowel disease within the Vaccine Safety Datalink network and evaluation of association with rotavirus vaccination

BackgroundRecent studies have reported an increase in Inflammatory bowel disease (IBD) incidence in young children, highlighting the need to better understand risk factors for the development of IBD. Licensed for use in infants in 2006, the oral, live-attenuated rotavirus vaccine has biologic plausibility for instigating inflammation of the gut mucosa as a pathway to immune dysregulation.MethodsOver a ten-year period, we evaluated incidence of IBD within a cohort of children under the age of ten, enrolled in seven integrated healthcare delivery systems. We conducted a nested case-control study to evaluate the association between rotavirus vaccination and IBD using conditional logistic regression. Cases were confirmed via medical record review and matched to non-IBD controls on date of birth, sex, and study site.ResultsAmong 2.4 million children under the age of 10 years, 333 cases of IBD were identified with onset between 2007 and 2016. The crude incidence of IBD increased slightly over the study period (p-value for trend = 0.046). Of the 333 cases, 227 (68%) were born prior to 2007. Forty-two cases born in 2007 or later, with continuous enrollment since birth were included in the case-control study and matched to 210 controls. The adjusted odds ratio for any rotavirus vaccination in IBD cases, compared to matched controls, was 0.72 (95% confidence interval 0.19–2.65).ConclusionsData from this large pediatric cohort demonstrate a small overall increase in IBD incidence in young children over a ten-year period. The data suggest that rotavirus vaccination is not associated with development of IBD.     

Association between vaccination status,symptom identification and healthcare use: Implications for test negative design observational studies

AimTo test the internal validity of the test-negative design (TND) by investigating associations between maternal influenza vaccination, and new virus detection episodes (VDEs), acute respiratory illness, and healthcare visits in their children.MethodsEighty-five children from a birth cohort provided daily symptoms, weekly nasal swabs, and healthcare use data until age 2-years. Effect estimates are summarised as incidence rate ratios (IRR).ResultsThere was no association between maternal vaccination and VDEs in children (IRR = 1.1; 95 %CI = 0.9–1.2). Influenza-vaccinated mothers were more likely than unvaccinated mothers to both report, and seek healthcare for, acute lower respiratory illness in their children, IRR = 2.4; 95 %CI = 1.2–4.8 and IRR = 2.2; 95 %CI = 1.1–4.3, respectively.ConclusionA key assumption of the TND, that healthcare seeking behaviour for conditions of the same severity is not associated with vaccine receipt, did not hold. Further studies of the performance of the TND in different populations are required to confirm its validity.     

The impact of a change in infant BCG vaccination policy on adolescent TB incidence rates: A South African population-level cohort study

ObjectiveSouth Africa’s infant Bacille Calmette Guerin (BCG) vaccine policy changed from percutaneous (PC) BCG Japan to intradermal (ID) BCG Denmark in 2000. This study investigated whether this change in infant BCG vaccination had any durable impact on TB incidence rates (IR) into adolescence.MethodsThe Cape Town electronic TB register provided data (from 2008 to 2018) on HIV-negative TB patients born in 1991–1999 (BCG Japan cohort) and 2001–2008 (BCG Denmark cohort). Statistics South Africa provided population estimates. Annual TB IR per 100,000 population were calculated stratified by age, gender and birth year. Interrupted time series analysis with a segmented Poisson regression and birth cohort analyses were used to compare incidence between the BCG cohorts and trends over time.FindingsTB IR increased throughout adolescence, with 17-year-olds having 7.34 [95% confidence interval (CI), 6.48–8.32] times higher TB IR than 10-year-olds. Females had 1.22 [95% CI 1.17–1.27] higher IR than males. Overall, adolescents who received ID BCG Denmark had a lower TB IR compared to PC BCG Japan (rate ratio 0.86, [95% CI 0.80–0.94]). No interaction between BCG and age, nor BCG and gender were identified. Birth cohort analyses showed the increase in TB IR started around one year earlier in females than in males.ConclusionThe change in infant BCG policy was associated with a modest decrease in TB incidence in 10- to 17-year-old HIV-negative adolescents. However, TB incidence rapidly increased with age in both adolescent cohorts and remained high despite BCG vaccination at birth.