Early impact of rotavirus vaccine in under 5 year old children hospitalized due to diarrhea,Swaziland

BackgroundSwaziland introduced rotavirus vaccine in the National Immunization Program, in May 2015, with the objective of reducing the burden of rotavirus diarrheal disease. We monitored the early impact of the vaccine in reducing rotavirus diarrhea.MethodsWe conducted sentinel rotavirus surveillance from January 2013 to December 2016 in children under five years of age admitted due to diarrhea attending Mbabane Government Referral Hospital in the Hhohho Region and Raleigh Fitkin Memorial Hospital in the Manzini Region. All cases had stool samples collected and tested for rotavirus antigen by enzyme immunoassay.ResultsBetween 2013 and 2016, 596 samples were collected and tested. Rotavirus positivity reduced from average of 50.8% (172/338) (in 2013–2014 (pre vaccine period)) to 29% (24/82) in 2016, post-vaccine introduction. The median age of children with rotavirus infection increased from average of 10 months in 2013–2014 to 13.7 months in 2016. The peak season for all-cause diarrhea and rotavirus-specific hospitalizations among children under five years of age was June–August in all years with a blunting of the peak season in 2016. Rotavirus positivity among children 0–11 months reduced from an average of 49% in 2013–2014 (116/236) to 33% (15/45) in 2016, a 33% reduction following rotavirus vaccine introduction.ConclusionThere has been a rapid reduction of all-cause diarrhea and rotavirus hospitalizations in Swaziland, particularly in young children and during the rotavirus season, after the introduction rotavirus vaccine. Continued surveillance is needed to monitor the long-term impact of rotavirus vaccine introduction.     

Influenza vaccine effectiveness: Maintained protection throughout the duration of influenza seasons 2010–2011 through 2013–2014

BackgroundFactors, such as age, comorbidities, vaccine type, herd immunity, previous influenza exposure, and antigenic shift may impact the immune response to the influenza vaccine, protection against circulating strains, and antibody waning. Evaluating vaccine effectiveness (VE) is important for informing timing of vaccine administration and evaluating overall vaccine benefit.MethodsVE was assessed using febrile respiratory illness surveillance among Department of Defense non-active duty beneficiaries from influenza seasons 2010–2011 through 2013–2014. Respiratory specimens were taken from participants meeting the case definition and tested by polymerase chain reaction for influenza. VE was calculated using logistic regression and by taking 1 minus the odds ratio of being vaccinated in the laboratory confirmed positive influenza cases versus laboratory confirmed negative controls.ResultsThis study included 1486 participants. We found an overall adjusted VE that provided significant and fairly consistent protection ranging from 54% to 67% during 0–180 days postvaccination. This VE dropped to −11% (95% confidence interval: −102% to 39%) during 181–365 days.ConclusionsOur study found moderate VE up to 6 months postvaccination. Since the influenza season starts at different times each year, optimal timing is difficult to predict. Consequently, early influenza vaccination may still offer the best overall protection.     

Introducing ROTAVAC® to the occupied Palestinian Territories: Impact on diarrhea incidence,rotavirus prevalence and genotype composition

BackgroundRotavirus infection remains an important cause of morbidity and mortality in children. The introduction of vaccination programs in more than 100 countries has contributed to a decrease in hospitalizations and mortality. This study investigates the epidemiological impact of the rotavirus vaccine ROTAVAC® in the Palestinian Territories, the first country to switch from ROTARIX® to this new vaccine.MethodsClinical surveillance data was collected from children younger than 5 attending outpatient clinics throughout Gaza with diarrhea between 2015 and 2020. The incidence of all-cause diarrhea was assessed using an interrupted time-series approach.Rotavirus prevalence was determined at the Caritas Baby Hospital in the West Bank using ELISA on stool specimen of children younger than 5 with diarrhea. Genotyping was performed on 325 randomly selected rotavirus-positive samples from January 2015 through December 2020 using multiplex PCR analysis.ResultsAverage monthly diarrhea cases dropped by 16.7% annually from introduction of rotavirus vaccination in May 2016 to the beginning of the SARS-CoV-2 epidemic in March 2020 for a total of 53%. Case count declines were maintained after the switch to ROTAVAC® in October 2018. Rotavirus positivity in stool samples declined by 67.1% over the same period without change following the switch to ROTAVAC®.The distribution of predominant genotypes in rotavirus-positive stool samples changed from a pre-vaccination G1P [8] to G9P[8] and G12P[8] during the ROTARIX® period and G2P[4] after the introduction of ROTAVAC®.ConclusionROTAVAC® has shown epidemiological impact on par with ROTARIX® after its introduction to the national immunization schedule in the Palestinian Territories. A molecular genotype shift from a pre-vaccination predominance of G1P[8] to a current predominance of G2P[4] requires more long-term surveillance.     

Impact of rotavirus vaccine on all-cause diarrhea and rotavirus hospitalizations in Madagascar

BackgroundRotavirus vaccine was introduced into the Extended Program on Immunization in Madagascar in May 2014. We analyzed trends in prevalence of all cause diarrhea and rotavirus hospitalization in children <5 years of age before and after vaccine introduction and assessed trend of circulating rotavirus genotypes at Centre Hospitalier Universitaire Mère Enfant Tsaralalàna (CHU MET).MethodsFrom January 2010 to December 2016, we reviewed the admission logbook to observe the rate of hospitalization caused by gastroenteritis among 19619 children <5 years of age admitted at the hospital. In June 2013–December 2016, active rotavirus surveillance was also conducted at CHUMET with support from WHO. Rotavirus antigen was detected by EIA from stool specimen of children who are eligible for rotavirus gastroenteritis surveillance at sentinel site laboratory and rotavirus positive specimens were further genotyped at Regional Reference Laboratory by RT-PCR.ResultsDiarrhea hospitalizations decreased after rotavirus vaccine introduction. The median proportion of annual hospitalizations due to diarrhea was 26% (range: 31–22%) before vaccine introduction; the proportion was 25% the year of vaccine introduction, 17% in 2015 and 16% in 2016. Rotavirus positivity paralleled patterns observed in diarrhea. Before vaccine introduction, 56% of stool specimens tested positive for rotavirus; the percent positive was 13% in 2015, 12% in 2016. Diverse genotypes were detected in the pre-vaccine period; the most common were G3P[8] (n = 53; 66%), G2P[4] (n = 12; 15%), and G1P[8] (n = 11; 14%). 6 distinct genotypes were found in 2015; the most common genotype was G2P[4] (n = 10; 67%), the remaining, 5, G12[P8], G3[P8], G1G3[P4], G3G12[P4][P8] and G1G3[NT] had one positive specimen each.ConclusionsFollowing rotavirus vaccine introduction all-cause diarrhea and rotavirus-specific hospitalizations declined dramatically. The most common genotypes detected in the pre-vaccine period were G3P[8] and G2P[4] in 2015, the post vaccine period.     

Dose-dependent effectiveness of acellular pertussis vaccine in infants: A population-based case-control study

BackgroundPertussis is a vaccine-preventable disease which is most severe in young infants. More than two decades after the introduction of acelluar pertussis vaccines (aPV) in national immunization programs in many countries worldwide, a resurgence of pertussis has been recognized. Suboptimal effectiveness of aPV has been blamed as one major reason but only few studies have evaluated dose-dependent vaccine effectiveness (VE) provided by aPV in current practice.MethodsWe performed a population-based retrospective case-control study by comparing pertussis immunization data of children 2.5 months to 2 years of age hospitalized for pertussis and residing in Switzerland with immunization data of a random control sample of children aged 2 years and residing in Switzerland. VE was defined as the percentage of hospitalizations avoided by number of aPV doses. It was calculated as 1-infection rate ratio (IRR)*100. IRR was calculated by dividing infection rates of vaccinated children and infection rates of unvaccinated children. To get dose specific VE, infection rates were stratified by number doses received.ResultsVE against hospitalization due to pertussis increased significantly with each consecutive aPV dose in a “3 + 1” primary course in infants: 42.1% (95% CI: 11.3–62.6), 83.9% (70.2–92.1), 98.2% (96.1–99.3), and 100% (97.9–100) after the 1st, 2nd, 3rd, and 4th dose, respectively.ConclusionAcellular pertussis vaccines continue to demonstrate protection against hospitalization due to pertussis in infants and young children. Therefore, together with advancing immunization of pregnant women and household contacts, better control of severe pertussis in young infants can be achieved by timely initiation of immunization.     

Estimates of pertussis vaccine effectiveness in United States air force pediatric dependents

BackgroundPertussis vaccination compliance is critical for reduction in the prevalence of disease; however, the current acellular pertussis vaccine may not provide sufficient protection from infection. This study examined acellular pertussis vaccine effectiveness (VE) for Air Force dependents less than 12 years of age.MethodsWe conducted a case-control study among Air Force pediatric dependents from 2011 to 2013, comparing cases with positive pertussis test results to controls who received the same lab tests with a negative result. Our study population was categorized by age group and vaccination status based on the Centers for Disease Control and Prevention recommended pertussis vaccination schedule. VE was calculated with respect to vaccination status and pertussis lab results.ResultsWe compared 27 pertussis laboratory positive cases with 974 pertussis laboratory negative controls, 2 months to <12 years old. Comparing completely vaccinated to non-vaccinated patients, the overall VE was 78.3% (95% confidence interval (CI): 48.6, 90.8; p < 0.001). VE was highest among those 15 months to <6 years old: 97.6% (95% CI: 78.5, 99.7; p < 0.001). Children 6 to <12 years old had the lowest VE: 48.5% (95% CI: −74.0, 84.7; p = 0.28). Comparing partially vaccinated patients to nonvaccinated patients yielded 64.2% (95% CI: −7.2, 88.1; p = 0.06) overall VE.ConclusionsAcellular pertussis vaccination was effective at preventing laboratory confirmed pertussis among our Air Force pediatric dependent population, with highest protection among completely vaccinated, young children. Older children received the lowest amount of protection. Partial vaccination had near significant protection. Our overall calculated pertussis VE corroborates other pertussis VE studies looking at similar age groups.     

Temporal association of rotavirus vaccination and genotype circulation in South Africa: Observations from 2002 to 2014

BackgroundRotavirus vaccination has reduced diarrhoeal morbidity and mortality globally. The monovalent rotavirus vaccine was introduced into the public immunization program in South Africa (SA) in 2009 and led to approximately 50% reduction in rotavirus hospitalization in young children. The aim of this study was to investigate the rotavirus genotype distribution in SA before and after vaccine introduction.Materials and methodsIn addition to pre-vaccine era surveillance conducted from 2002 to 2008 at Dr George Mukhari Hospital (DGM), rotavirus surveillance among children <5 years hospitalized for acute diarrhoea was established at seven sentinel sites in SA from April 2009 to December 2014. Stool specimens were screened by enzyme immunoassay and rotavirus positive specimens genotyped using standardised methods.ResultsAt DGM, there was a significant decrease in G1 strains from pre-vaccine introduction (34%; 479/1418; 2002–2009) compared to post-vaccine introduction (22%; 37/170; 2010–2014; p for trend <.001). Similarly, there was a significant increase in non-G1P[8] strains at this site (p for trend <.001). In expanded sentinel surveillance, when adjusted for age and site, the odds of rotavirus detection in hospitalized children with diarrhoea declined significantly from 2009 (46%; 423/917) to 2014 (22%; 205/939; p < .001). The odds of G1 detection declined significantly from 2009 (53%; 224/421) to 2010–2011 (26%; 183/703; aOR = 0.5; p < .001) and 2012–2014 (9%; 80/905; aOR = 0.1; p < .001). Non-G1P[8] strains showed a significant increase from 2009 (33%; 139/421) to 2012–2014 (52%; 473/905; aOR = 2.5; p < .001).ConclusionsRotavirus vaccination of children was associated with temporal changes in circulating genotypes. Despite these temporal changes in circulating genotypes, the overall reduction in rotavirus disease in South Africa remains significant.     

Impact of rotavirus vaccination on diarrhea-related hospitalizations in São Paulo State,Brazil

IntroductionFollowing introduction of routine infant rotavirus vaccination, severe diarrhea hospitalization rates declined among children aged <5 years throughout Brazil. Ensuring equity of rotavirus vaccine impact is important in countries that self-finance immunization programs. The objective of this study was to examine rotavirus vaccine impact on diarrhea admission rates among children aged <5 years in Brazil's public health system, according to area-based measures of human development in the state of São Paulo, Brazil.MethodsEcological analysis of public health system hospitalization rates for acute gastroenteritis among children aged <5 years in the state of São Paulo, Brazil, according to five categories of municipal development based on a modified Human Development Index for municipalities. Acute gastroenteritis hospitalization rates among children aged <5 years after national rotavirus vaccine introduction (2008–2011) were compared to rates in pre-vaccine years (2000–2005) to calculate percent decline in rates (1 − rate ratio) and 95% confidence intervals (CI) for each municipal development category. Direct hospitalization costs during the two periods were compared.ResultsAnnual rates declined by 40% (95% CI, 39–42%) from 631 diarrhea hospitalizations per 100,000 person years pre-rotavirus vaccination to 377 per 100,000 post-vaccination among children aged <5 years and 50% (95% CI, 48–52%) from 1009 to 505 per 100,000 among infants. Highest rates were observed in least developed municipalities. Significant declines of 26–52% among children <5 years and 41–63% among infants were observed in all categories of municipal development. Lower diarrhea hospitalization rates resulted in annual savings of approximately 2 million USD for the state of São Paulo. Savings in direct hospitalization costs benefitted municipalities in all five categories.ConclusionThe introduction of rotavirus vaccination was associated with substantial reductions of diarrhea-related admissions at all levels of municipal development in São Paulo State, Brazil.     

Influenza vaccines effectiveness 2013–14 through 2015–16, a test-negative study in children

BackgroundTrivalent inactivated and live attenuated influenza vaccines (IIV3 and LAIV3) have been reformulated with an extra B strain (IIV4 and LAIV4). They were licensed based on immunogenicity and their effectiveness (VE) still must be empirically tested.MethodsChildren 1–17 years tested for influenza during 2013–16 were included and their immunization status verified. They were considered vaccinated if received ≥1 dose of an influenza vaccine ≥10 days before evaluated for a respiratory episode. Age-groups were classified as 1–4 years or 5–17 years. VE was estimated by comparing vaccination status of influenza-positive versus influenza-negative cases.Results6779 children were enrolled in the three seasons. Overall, 27.2% received an influenza vaccine (87.1% IIV3 or IIV4 and 12.9% LAIV4), and 15.6% tested positive for influenza (77.9% A). IIV3 was predominantly used in 2013–14 and IIV4 in 2014–15 and 2015–16. IIV3 and IIV4 had comparable VE over the three seasons (60%, 57% and 53%) and performed similarly against influenza A and B and both age-groups. LAIV4 performed poorly for influenza A (15%, 37% and 48%) but better for influenza B (100%, 56% and 100%), especially among children 5–17 years of age with VE = 100% (95%CI: 55, 100).ConclusionsInfluenza vaccination showed modest but consistent effectiveness over the years. The switch from IIV3 to IIV4 did not affect VE. LAIV4 did not perform as well as IIVs, yet it improved over the years and was particularly good protecting older children against influenza B. These results emphasize the regional nature of influenza and the need for local surveillance.     

Effectiveness of Lanzhou lamb rotavirus vaccine in preventing gastroenteritis among children younger than 5 years of age

BackgroundLanzhou Lamb rotavirus (LLR) vaccine was licensed in China in 2000. It was the only vaccine available in private market before 2018. However, the data about the post-marketing effectiveness is very limited. To assess the vaccine effectiveness (VE), we conducted a case-control study based on the hospital surveillance system in Beijing from 2015 to 2017.MethodsSeven hospitals located in seven districts in Beijing, from October 1, 2015, to March 31, 2017, were included. The VE of LLR vaccine was assessed in laboratory-confirmed rotavirus infection among children younger than five years old through a case-control design, using rotavirus-negative cases as controls. LLR vaccination was documented from a vaccination registry. VE was estimated adjusting for age group, gender, study site, the month of illness onset and interval days between illness onset to sampling through a logistic regression model.ResultsA total of 598 cases and 1766 controls were included in this study. The vaccine average coverage rate during 2015–2017 among children younger than five years old was 10.8% in Beijing. The adjusted VE for LLR vaccine of 1 dose versus 0 dose was 34.9% (95%CI, 5.3–55.3). We also obtained the adjusted VE of 87.7% (95%CI, 32.7–97.8) for patients with the severity score ≥11, 36.2% (95%CI, 4.7–57.3) for children of 2–35 months age group and 40.8% (95%CI, 7.8–61.9) against G9 rotavirus infection. Vaccinated cases were less likely to have watery stool (OR = 0.42) and have diarrhea longer than 5 days (OR = 0.47) than unvaccinated cases.DiscussionLLR vaccine conferred protection against rotavirus disease. Children who were vaccinated presented with less severe clinical manifestations. An immunization schedule of receiving all three doses in the first year should be preferred.     

Impact of rotavirus vaccination on rotavirus and all-cause gastroenteritis in peri-urban Kenyan children

A monovalent rotavirus vaccine (RV1) was introduced into the National Immunization Program in Kenya in July 2014. We examined the impact of the vaccine on hospitalization for all-cause acute gastroenteritis (AGE) and rotavirus-specific AGE and strain distribution at a large referral hospital which serves a predominantly peri-urban population in Central Kenya. Data on rotavirus AGE and strain distribution were derived from ongoing hospital-based AGE surveillance. Hospital administrative data were used to compare trends in all-cause AGE. Pre-vaccine (July 2009–June 2014) and post-vaccine (July 2014–June 2016) periods were compared for changes in hospitalization for all-cause AGE and rotavirus AGE and strain distribution. Following the vaccine introduction, the proportion of children aged <5 years hospitalized for rotavirus declined by 30% (95% CI: 19–45%) in the first year and 64% (95% CI: 49–77%) in the second year. Reductions in rotavirus positivity were most pronounced among the vaccine-eligible group (<12 months) in the first year post-vaccination at 42% (95% CI: 28–56%). Greater reductions of 67% (95% CI: 51–79%) were seen in the second year in the 12–23 months age group. Similarly, hospitalizations for all-cause AGE among children <5 years of age decreased by 31% (95% CI: 24–40%) in the first year and 58% (95% CI: 49–67%) in the second year of vaccine introduction. Seasonal peaks of rotavirus and all-cause AGE were reduced substantially. There was an increased detection of G2P[4], G3P[6] and G3P[8], which coincided temporally with the timing of the vaccine introduction. Thus, introducing the rotavirus vaccine into the routine immunization program in Kenya has resulted in a notable decline in rotavirus and all-cause AGE hospitalizations in Central Kenya. This provides early evidence for public health policy makers in Kenya to support the sustained use of the rotavirus vaccine in routine immunizations.     

Field evaluation of measles vaccine effectiveness among children in the Democratic Republic of Congo

BackgroundLarge-scale measles outbreaks in areas with high administrative vaccine coverage rates suggest the need to re-evaluate measles prevention and control in the Democratic Republic of Congo (DRC). Monitoring of measles Vaccine Effectiveness (VE) is a useful measure of quality control in immunization programs. We estimated measles VE among children aged 12–59 months in the Democratic Republic of Congo (DRC) using laboratory surveillance data from 2010–2012.MethodsWe used the case-based surveillance system with laboratory confirmation to conduct a case-control study using the test negative design. Cases and controls were selected based on presence (n = 1044) or absence (n = 1335) of measles specific antibody IgM or epidemiologic linkage. Risk factors for measles were assessed using unconditional logistic regression, stratified by age.ResultsAmong children 12–59 months, measles vaccination was protective against measles [aOR (95% C)], 0.20 (0.15–0.26) and estimated VE was 80% (95% CI 74–85%). Year of diagnosis, 2011: 6.02 (4.16–8.72) and 2012; 8.31 (5.57–12.40) was a risk factor for measles when compared to 2010. Compared to Kinshasa, children in Bas-Congo, Kasai-Oriental, Maniema and South Kivu provinces all had higher odds of developing measles. Measles VE was similar for children 12–23 months and 24–59 months (80% and 81% respectively).ConclusionsRepeated occurrences of measles outbreaks and lower than expected VE estimates suggest the need to further evaluate measles vaccine efficacy and improve vaccine delivery strategies in DRC.     

Vaccine effectiveness of tetanus toxoid,reduced diphtheria toxoid,and acellular pertussis vaccine during a pertussis outbreak in Maine

BackgroundMultiple school-associated pertussis outbreaks were reported in Maine from 2010 to 2011. These outbreaks were associated with an overall increase in pertussis cases statewide. Waning of protection in students recently vaccinated with tetanus, diphtheria, and acellular pertussis (Tdap) has been implicated in the increase in reported rates of pertussis nationally.MethodsWe conducted a retrospective cohort study to evaluate Tdap vaccine effectiveness (VE) among students aged 11–19 years in two schools reporting outbreaks in 2011. All pertussis cases reported from August through November, 2011 at the two schools were included. Vaccination history was verified using provider information, state vaccine registry data, and parental verification. Attack rates (AR) were calculated. VE and duration of protection was calculated as VE = 1 − (AR_vaccinated/AR_unvaccinated) × 100% using a log binomial regression model.ResultsOf 416 students enrolled, 314 were included in the analyses. Twenty-nine cases collectively in Schools A and B. Tdap coverage was 65% at School A and 42% at School B before the start of the outbreak. Among students enrolled in the study, attack rates were 11.9% and 7.7% at Schools A and B, respectively. Overall VE was 68.5% (95% confidence interval (CI) 37.7–86.2). VE was 70.4% (95% CI 17.5–89.4) for School A and 65.2% (95% CI −19.2 to 89.9) for School B. VE <2 years versus ≥2 years from outbreak onset was not significantly different.ConclusionsTdap was moderately effective in preventing disease among vaccinated students. Vaccine coverage of 65% or less was suboptimal and might contribute to outbreaks. Waning VE was not demonstrated. Increased vaccination coverage rates as well as further evaluation of the role of acellular vaccine on VE is needed.     

Effect of propensity of seeking medical care on the bias of the estimated effectiveness of rotavirus vaccines from studies using a test-negative case-control design

BackgroundRotavirus is the leading cause of severe diarrhea among children worldwide, and vaccines can reduce morbidity and mortality by 50–98%. The test-negative control (TNC) study design is increasingly used for evaluating the effectiveness of vaccines against rotavirus and other vaccine-preventable diseases. In this study design, symptomatic patients who seek medical care are tested for the pathogen of interest. Those who test positive (negative) are classified as cases (controls).MethodsWe use a probability model to evaluate the bias of estimates of rotavirus vaccine effectiveness (VE) against rotavirus diarrhea resulting in hospitalization in the presence of possible confounding and selection biases due to differences in the propensity of seeking medical care (PSMC) between vaccinated and unvaccinated children.ResultsThe TNC-based VE estimate corrects for confounding bias when the confounder’s effects on the probabilities of rotavirus and non-rotavirus related hospitalizations are equal. If this condition is not met, then the estimated VE may be substantially biased. The bias is more severe in low-income countries, where VE is known to be lower. Under our model, differences in PSMC between vaccinated and unvaccinated children do not result in selection bias when the TNC study design is used.ConclusionsIn practice, one can expect the association of PSMC (or other potential confounders) with the probabilities of rotavirus and non-rotavirus related hospitalization to be similar, in which case the confounding effects will only result in small bias in the VE estimate from TNC studies. The results of this work, along with those of our previous paper, confirm the TNC design can be expected to provide reliable estimates of rotavirus VE in both high- and low-income countries.     

Impact and effectiveness of monovalent rotavirus vaccine in Tajik children

BackgroundIn 2015, Tajikistan became the second country in Central Asia to introduce rotavirus vaccine into its national immunization program. Before vaccine introduction, rotavirus was estimated to cause > 40% of pediatric diarrhea hospitalizations in Tajikistan. We aimed to assess the impact of rotavirus vaccine introduction on rotavirus disease burden and estimate rotavirus vaccine effectiveness (VE).MethodsUsing surveillance data from 2013 through 2019, we examined trends in monthly hospital admissions among children < 5 years old, before and after rotavirus vaccine introduction. Poisson regression was used to quantify decreases. VE was estimated using a test-negative case control design, with data from admissions during 2017 – 2019. Immunization records were obtained from clinics.ResultsAmong enrolled children, rotavirus positivity declined from 42% to 25% in the post-vaccine introduction period, a decrease of 41% (95% Confidence Interval [CI]: 36 – 45%). Declines were greatest in children < 12 months of age. Estimated VE of a complete course of rotavirus vaccine was 55% (95% CI: 21 – 73%) among children 5 – 59 months of age and 64% (95% CI: 36 – 80%) among children 5 – 23 months of age. VE point estimates were higher among children receiving both doses of rotavirus vaccine non-concurrently with OPV and among children receiving their first dose of rotavirus vaccine at 4 – 11 months of age, but CIs were wide and overlapping.ConclusionsOur data demonstrate that rotavirus vaccine introduction was associated with a substantial reduction in pediatric rotavirus hospitalization burden in Tajikistan, and that rotavirus vaccination is effective in Tajik children.     

Age-specific effectiveness following each dose of acellular pertussis vaccine among infants and children in New Zealand

BackgroundThough it is believed the switch from whole cell to acellular pertussis vaccine has contributed to the resurgence of pertussis disease, few studies have evaluated vaccine effectiveness (VE) and duration of protection provided by an acellular vaccine schedule including three primary doses but no toddler-age dose. We assessed this schedule in New Zealand (NZ), a setting with historically high rates of pertussis disease, and low but recently improved immunisation coverage. We further evaluated protection following the preschool-age booster dose.MethodsWe performed a nested case-control study using national-level healthcare data. Hospitalised and non-hospitalised pertussis was detected among children 6 weeks to 7 years of age between January 2006 and December 2013. The NZ National Immunisation Register provided vaccination status for cases and controls. Conditional logistic regression was used to calculate dose-specific VE with duration of immunity examined by stratifying VE into ages aligned with the immunisation schedule.ResultsVE against pertussis hospitalisation was 93% (95% confidence interval [CI]: 87, 96) following three doses among infants aged 5–11 months who received three compared to zero doses. This protection was sustained through children’s fourth birthdays (VE ⩾ 91%). VE against non-hospitalised pertussis was also sustained after three doses, from 86% (95% CI: 80, 90) among 5–11 month olds to 84% (95% CI: 80, 88) among 3-year-olds. Following the first booster dose at 4 years of age, the protective VE of 93% (95% CI: 90, 95) among 4-year-olds continued through 7 years of age (VE ⩾ 91%).ConclusionsWe found a high level of protection with no reduction in VE following both the primary course and the first booster dose. These findings support a 3-dose primary course of acellular vaccine with no booster dose until 4 years of age.     

Impact and effectiveness of pentavalent rotavirus vaccine in children <5 years of age in Burkina Faso

BackgroundBurkina Faso was one of the first African nations to introduce pentavalent rotavirus vaccine (RV5, RotaTeq) into its national immunization program in October 2013. We describe the impact and effectiveness of rotavirus vaccine on acute gastroenteritis (AGE) hospitalizations among Burkinabe children.MethodsSentinel hospital-based surveillance for AGE was conducted at four hospitals during December 2013 – February 2017. Demographic, clinical, and vaccination information was collected and stool specimens were tested by EIA. Trends in rotavirus AGE hospitalizations and changes in the proportion of AGE hospitalizations due to rotavirus were examined at two sentinel sites from January 2014 – December 2016. Unconditional logistic regression models using data from all 4 surveillance sites were used to calculate vaccine effectiveness (VE, defined as 1-odds ratio) by comparing the odds of vaccination among rotavirus AGE (cases) and non-rotavirus AGE (controls) patients, controlling for age, season, hospital site and socioeconomic factors.ResultsThe proportion of AGE hospitalizations that tested positive for rotavirus declined significantly among children <5 years of age, from 36% (154/422) in 2014 to 22% (71/323, 40% reduction, p < .01) in 2015 and 20% (61/298, 44% reduction, p < .01) in 2016. Among infants, the percentage of AGE admissions due to rotavirus fell significantly from 38% (94/250) in 2014 to 21% (32/153, 44% reduction, p < .01) in 2015 and 17% (26/149, 54% reduction, p < .01) in 2016. The adjusted VE for full 3-dose series of RV5 against rotavirus hospitalization was 58% (95% [CI], 10%, 81%) in children 6–11 months of age and 19% (−78%, 63%) in children ≥12 months.ConclusionRotavirus hospitalizations declined after introduction of pentavalent rotavirus vaccine in children, particularly among infants. RV5 significantly protected against severe rotavirus gastroenteritis in infants, but effectiveness decreased in older children.     

Seasonal influenza vaccine effectiveness against medically attended influenza illness among children aged 6–59 months,October 2011–September 2012: A matched test-negative case–control study in Suzhou,China

BackgroundSeasonal influenza infections among young children in China lead to substantial numbers of hospitalizations and financial burden. This study assessed the seasonal influenza vaccine effectiveness (VE) against laboratory confirmed medically attended influenza illness among children in Suzhou, China, from October 2011–September 2012.MethodsWe conducted a test-negative case–control study among children aged 6–59 months who sought care at Soochow University Affiliated Children's Hospital (SCH) from October 2011–September 2012. A case was defined as a child with influenza-like illness (ILI) or severe acute respiratory infection (SARI) with an influenza-positive nasopharyngeal swab by rRT-PCR. Controls were selected from children presenting with ILI or SARI without laboratory confirmed influenza. We conducted 1:1 matching by age and admission date. Vaccination status was verified from the citywide immunization system database. VE was calculated with conditional logistic regression: (1 − OR) × 100%.ResultDuring the study period, 2634 children aged 6–59 months presented to SCH with ILI (1975) or SARI (659) and were tested for influenza. The vaccination records were available for 69% (1829; ILI: 1354, SARI: 475). Among those, 23% (427) tested positive for influenza, and were included as cases. Among influenza positive cases, the vaccination rates were 3.2% for SARI and 4.5% for ILI. Among controls, the vaccination rates were 13% for SARI, and 11% for ILI. The overall VE against lab-confirmed medically attended influenza virus infection was 67% (95% CI: 41–82). The VE for SARI was 75% (95% CI: 11–93) and for ILI was 64% (95% CI: 31–82).ConclusionsThe seasonal influenza vaccine was effective against medically attended lab-confirmed influenza infection in children aged 6–59 months in Suzhou, China in the 2011–12 influenza season. Increasing seasonal influenza vaccination among young children in Suzhou may decrease medically attended influenza-associated ILI and SARI cases in this population.     

Impact of routine rotavirus vaccination on all-cause and rotavirus hospitalizations during the first four years following vaccine introduction in Rwanda

BackgroundRwanda introduced pentavalent rotavirus vaccine into its national immunization program in 2012. To determine the long-term impact of rotavirus vaccine on disease burden in a high burden setting, we examined trends in rotavirus and all-cause diarrhea hospitalizations in the first four years following rotavirus vaccine introduction.MethodsWe used data from an active surveillance system, from a review of pediatric ward registries, and from the Health Management Information System to describe trends in rotavirus and all-cause diarrhea hospitalizations from January 2009 through December 2016. Percent reductions were calculated to compare the number of all-cause and rotavirus diarrhea hospitalizations pre- and post-rotavirus vaccine introduction.ResultsThe proportion of diarrhea hospitalizations due to rotavirus declined by 25–44% among all children <5 years of age during 2013–2015 with a shift in rotavirus hospitalizations to older age groups. The proportion of total hospitalizations due to diarrhea among children <5 years of age decreased from 19% pre-vaccine introduction to 12–13% post-vaccine introduction. In the national hospital discharge data, substantial decreases were observed in all-cause diarrhea hospitalizations among children <5 years of age in 2013 and 2014 but these gains lessened in 2015–2016.DiscussionContinued monitoring of long-term trends in all-cause diarrhea and rotavirus hospitalizations is important to ensure that the impact of the vaccination program is sustained over time and to better understand the changing age dynamics of diarrhea and rotavirus hospitalizations in the post-vaccine introduction era.