Monovalent Rotavirus Vaccine Research Articles

Impact of Rotavirus Vaccine Introduction and Postintroduction Etiology of Diarrhea Requiring Hospital Admission in Haydom, Tanzania, a Rural African Setting.

No data are available on the etiology of diarrhea requiring hospitalization after rotavirus vaccine introduction in Africa. The monovalent rotavirus vaccine was introduced in Tanzania on 1 January 2013. We performed a vaccine impact and effectiveness study as well as a quantitative polymerase chain reaction (qPCR)-based etiology study at a rural Tanzanian hospital. We obtained data on admissions among children <5 years to Haydom Lutheran Hospital between 1 January 2010 and 31 December 2015 and estimated the impact of vaccine introduction on all-cause diarrhea admissions. We then performed a vaccine effectiveness study using the test-negative design. Finally, we tested diarrheal specimens during 2015 by qPCR for a broad range of enteropathogens and calculated pathogen-specific attributable fractions (AFs). Vaccine introduction was associated with a 44.9% (95% confidence interval [CI], 17.6%-97.4%) reduction in diarrhea admissions in 2015, as well as delay of the rotavirus season. The effectiveness of 2 doses of vaccine was 74.8% (95% CI, -8.2% to 94.1%) using an enzyme immunoassay-based case definition and 85.1% (95% CI, 26.5%-97.0%) using a qPCR-based case definition. Among 146 children enrolled in 2015, rotavirus remained the leading etiology of diarrhea requiring hospitalization (AF, 25.8% [95% CI, 24.4%-26.7%]), followed by heat-stable enterotoxin-producing Escherichia coli (AF, 18.4% [95% CI, 12.9%-21.9%]), Shigella/enteroinvasive E. coli (AF, 14.5% [95% CI, 10.2%-22.8%]), and Cryptosporidium (AF, 7.9% [95% CI, 6.2%-9.3%]). Despite the clear impact of vaccine introduction in this setting, rotavirus remained the leading etiology of diarrhea requiring hospitalization. Further efforts to maximize vaccine coverage and improve vaccine performance in these settings are warranted.

Rotavirus Vaccine Schedules and Vaccine Response Among Infants in Low- and Middle-Income Countries: A Systematic Review.

BackgroundRotavirus vaccine schedules may impact vaccine response among children in low- and middle-income countries (LMICs). Our objective was to review the literature evaluating the effects of monovalent (RV1) or pentavalent rotavirus vaccines schedules on vaccine response.MethodsWe searched PubMed, Web of Science, Embase, and ClinicalTrials.gov for eligible trials conducted in LMICs comparing ≥2 vaccine schedules and reporting immunologic response or efficacy. We calculated seroconversion proportion differences and geometric mean concentration (GMC) ratios with 95% confidence intervals.ResultsWe abstracted data from 8 eligible trials of RV1. The point estimates for seroconversion proportions difference ranged from −0.25 to −0.09 for the 6/10-week schedule compared with 10/14. The range for the 6/10/14- compared with 10/14-week schedule was −0.02 to 0.10. Patterns were similar for GMC ratios and efficacy estimates.ConclusionsThe commonly used 6/10-week RV1 schedule in LMICs may not be optimal. Further research on the effect of rotavirus schedules using clinical endpoints is essential.

Comparative analysis of the immunogenicity of monovalent and multivalent rotavirus immunogens

The strategies for developing rotavirus (RV) vaccines have always been controversial. At present, both the monovalent RV vaccine and the multivalent RV vaccine have displayed excellent safety and efficacy against RV infection and shown cross-reactive immunity, which laid the question whether the multivalent RV vaccine could be replaced by the monovalent RV vaccine. In this study, we focused on comparing the immunogenicity (serum neutralization activity and protection against homotypic and heterotypic RVs’ challenge) of individual standard RV strains (monovalent RV immunogens) and different combinations of them (multivalent RV immunogens). In result, RV immunogens showed general immunogenicity and heterotypic reaction but the multivalent RV immunogens exhibited greater serum neutralization activity and stronger heterotypic reaction than the monovalent RV immunogens (P<0.05). As to the protection, the multivalent RV immunogens also revealed more rapid and stronger protection against homotypic and heterotypic RVs’ challenge than the monovalent RV immunogens. The results demonstrated that both the monovalent and multivalent RV immunogens exhibited high immunogenicity, but the monovalent RV immunogens could not provide enough neutralization antibodies to protect MA104 cells against the infection with heterotypic RV strains and timely protection against homotypic and heterotypic RVs, so the multivalent RV vaccine could not be replaced by the monovalent RV vaccine.

Changes in Rotavirus Genotypes before and after Vaccine Introduction: a Multicenter, Prospective Observational Study in Three Areas of Japan.

In Japan, monovalent and pentavalent rotavirus (RV) vaccines were approved in 2011 and 2012, respectively. To monitor changes in the RV genotypes before and after vaccine introduction, we performed a prospective observational study among children (＜ 5 years) with gastroenteritis who tested RV-positive on antigen rapid tests. Stool samples were collected from 3 different sites in Japan: Tsu City, Mie Prefecture; Kurashiki City, Okayama Prefecture; and Isumi City, Chiba Prefecture. RV genotypes were determined using reverse transcription-polymerase chain reaction. In Tsu City, G3P[8] was dominant (61.0-77.1%) before vaccine introduction, but decreased after introduction. Meanwhile, in an inverse proportion to the decrease in G3P[8], G1P[8] increased until the 2013/14 season, when a sudden predominance of G2P[4] (100%) occurred. A similar trend was observed in Kurashiki City in terms of the extent of reduction in G3P[8] and the emergence of G2P[4]. In Isumi City, G1P[8] was dominant (70.3%) before vaccine introduction, and G9P[8] became predominant (83.3%) in the 2013/14 season. To determine whether the genotype changes are attributable to vaccines or natural epidemiological changes, ongoing continuous monitoring of the RV genotypes is required.

Rotavirus vaccine effectiveness in low-income settings: An evaluation of the test-negative design

BackgroundThe test-negative design (TND), an epidemiologic method currently used to measure rotavirus vaccine (RV) effectiveness, compares the vaccination status of rotavirus-positive cases and rotavirus-negative controls meeting a pre-defined case definition for acute gastroenteritis. Despite the use of this study design in low-income settings, the TND has not been evaluated to measure rotavirus vaccine effectiveness. MethodsThis study builds upon prior methods to evaluate the use of the TND for influenza vaccine using a randomized controlled clinical trial database. Test-negative vaccine effectiveness (VE-TND) estimates were derived from three large randomized placebo-controlled trials (RCTs) of monovalent (RV1) and pentavalent (RV5) rotavirus vaccines in sub-Saharan Africa and Asia. Derived VE-TND estimates were compared to the original RCT vaccine efficacy estimates (VE-RCTs). The core assumption of the TND (i.e., rotavirus vaccine has no effect on rotavirus-negative diarrhea) was also assessed. ResultsTND vaccine effectiveness estimates were nearly equivalent to original RCT vaccine efficacy estimates. Neither RV had a substantial effect on rotavirus-negative diarrhea. ConclusionsThis study supports the TND as an appropriate epidemiologic study design to measure rotavirus vaccine effectiveness in low-income settings.

Changing molecular epidemiology of rotavirus infection after introduction of monovalent rotavirus vaccination in Scotland

BackgroundRotaviruses (RV) are the leading cause of gastroenteritis in children less than five years of age worldwide. Rotarix®, a live attenuated monovalent vaccine containing a RV strain of G1P[8] specificity has been included in the childhood immunisation schedule from June 2013 in Scotland. This study aimed to characterise the prevalent RV strains in Scotland before and after the introduction of the RV vaccine. MethodsRV positive faecal samples from Scottish virology laboratories covering the years 2012–2015 were genotyped. Viral RNA was extracted from faecal suspensions. VP7 and VP4 gene specific primers were used for multiplex hemi-nested PCRs and sequencing. Mann-Whitney U test and Chi-square test were used for statistical comparison. ResultsThere was a decrease in RV positive samples from the Scottish virology laboratories from 7409 samples in the pre-vaccination years (2009–2013) to 760 in 2014–2015, with an annual reduction of RV infections by 74.4% (RR-3.95; 95%-CI, 3.53–4.42, p<0.001). 362 samples from the pre-vaccination period and 278 samples from the post-vaccination were genotyped. There was a drop in prevalence of G1P[8] strains (72.1%, 95%-CI, 67.42–76.33 to 15%, 95%-CI, 11.38–19.79) after introduction of the vaccine. In the post-vaccination period G2P[4] was the dominant strain in Scotland (21.9%, 95%-CI, 17.48–27.17) with increase in G9P[8] (12.9%, 95%-CI, 9.50–7.41), G12P[8] (12.2%, 95%-CI, 8.89–16.60) and G3P[8] (11.9%, 95%-CI, 8.58–16.20) infections. Phylogenetic analysis of the VP7 and VP4 genes showed no major differences between the pre and post-vaccination G1P[8] strains. ConclusionThis laboratory based surveillance study shows significant reduction in reported RV cases and a shift in proportion from G1P[8] to G2P[4] strains after introduction of RV vaccination in Scotland. The genotyping data from a subset of the total reported RV cases will be used to ascertain cross protection against strains and identify vaccine induced RV strain shifts in the years to come.

Monovalent Rotavirus Vaccine Effectiveness and Impact on Rotavirus Hospitalizations in Zanzibar, Tanzania: Data From the First 3 Years After Introduction.

Low-income settings challenge the level of protection provided by live attenuated oral rotavirus vaccines. Rotarix (RV1) was introduced in the United Republic of Tanzania in early 2013, with 2 doses given at the World Health Organization-recommended schedule of ages 6 and 10 weeks, along with oral poliovirus vaccine. We performed active surveillance for rotavirus hospitalizations at the largest hospital in Zanzibar, Tanzania, from 2010 through 2015. Using a case-test-negative control design, we estimated the vaccine effectiveness (VE) of 2 RV1 doses in preventing rotavirus hospitalizations. Based on 204 rotavirus case patients and 601 test-negative controls aged 5-23 months, the VE of 2 RV1 doses against hospitalization for rotavirus diarrhea was 57% (95% confidence interval, 14%-78%). VE tended to increase against hospitalizations with higher severity, reaching 69% (95% confidence interval, 15%-88%) against the severity score for the top quarter of case patients. Compared with the prevaccine period, there were estimated reductions of 40%, 46%, and 69% in the number of rotavirus hospitalizations among infants in 2013, 2014, and 2015, respectively, and reductions of 36%, 26%, and 64%, respectively, among children aged <5 years. With data encompassing 3 years before and 3 years after vaccine introduction, our results indicate that successful delivery of RV1 on the current World Health Organization schedule can provide substantial health benefits in a resource-limited setting.

Validation of current procedural terminology codes for rotavirus vaccination among infants in two commercially insured US populations

We validated procedure codes used in health insurance claims for reimbursement of rotavirus vaccination by comparing claims for monovalent live-attenuated human rotavirus vaccine (RV1) and live, oral pentavalent rotavirus vaccine (RV5) to medical records. Using administrative data from two commercially insured United States populations, we randomly sampled vaccination claims for RV1 and RV5 from a cohort of infants aged less than 1 year from an ongoing post-licensure safety study of rotavirus vaccines. The codes for RV1 and RV5 found in claims were confirmed through medical record review. The positive predictive value (PPV) of the Current Procedural Terminology codes for RV1 and RV5 was calculated as the number of medical record-confirmed vaccinations divided by the number of medical records obtained. Medical record review confirmed 92 of 104 RV1 vaccination claims (PPV: 88.5%; 95% CI: 80.7-93.9%) and 98 of 113 RV5 vaccination claims (PPV: 86.7%; 95% CI: 79.1-92.4%). Among the 217 medical records abstracted, only three (1.4%) of vaccinations were misclassified in claims-all were RV5 misclassified as RV1. The medical records corresponding to 9 RV1 and 15 RV5 claims contained insufficient information to classify the type of rotavirus vaccine. Misclassification of rotavirus vaccines is infrequent within claims. The PPVs reported here are conservative estimates as those with insufficient information in the medical records were assumed to be incorrectly coded in the claims. Copyright © 2016 John Wiley & Sons, Ltd.

Rotavirus Vaccine and Intussusception Hospitalizations.

* Abbreviations: RV1 — : monovalent rotavirus vaccine RV5 — : pentavalent rotavirus vaccine There are 2 US Food and Drug Administration–approved vaccines for the prevention of rotavirus gastroenteritis in infants. Rotarix is a live, oral, monovalent rotavirus vaccine (RV1) administered as a 2-dose series, and RotaTeq is a live, oral, pentavalent rotavirus vaccine (RV5) administered as a 3-dose series. RV1 and RV5 are typically administered along with other routinely recommended vaccines at the 2- and 4-month well-child visits, with the third dose of RV5 administered at the 6-month visit. Because a previously licensed rotavirus vaccine, RotaShield, was associated with an increased risk of intussusception, prelicensure safety studies of >60 000 children for both RV1 and RV5 were conducted to assess for the occurrence of intussusception.1,2 Although these studies showed no increased risk of intussusception, subsequent postmarketing studies have demonstrated small increased risks of intussusception for both vaccines, primarily after first doses and, to a lesser extent, after the second doses.3–8 In this issue of Pediatrics , Tate and colleagues compared the years pre- and postintroduction of rotavirus vaccines in the United States and found no significant difference in intussusception hospitalization rates in children <12 months of age comparing the 2 time periods.9 However, in children 8 to 11 weeks of age, the … Address correspondence to Emmanuel B. Walter, MD, MPH, Duke Clinical Vaccine Unit, 2608 Erwin Rd, Suite 210, Durham, NC 27705. E-mail: walte002{at}mc.duke.edu

Effectiveness of rotavirus vaccine in preventing severe gastroenteritis in young children according to socioeconomic status

ABSTRACTIn 2011, the monovalent rotavirus vaccine was introduced into a universal immunization program in Quebec (Canada). This retrospective cohort study assessed vaccine effectiveness (VE) in preventing acute gastroenteritis (AGE) and rotavirus gastroenteritis (RVGE) hospitalizations among children <3 y living in the Quebec Eastern Townships region according to socioeconomic status (SES). Data were gathered from a tertiary hospital database paired with a regional immunization registry. Three cohorts of children were followed: (1) vaccinated children born in post-universal vaccination period (2011–2013, n = 5,033), (2) unvaccinated children born in post-universal vaccination period (n = 1,239), and (3) unvaccinated children born in pre-universal vaccination period (2008–2010, n = 6,436). In each cohort, AGE and RVGE hospitalizations were identified during equivalent follow-up periods to calculate VE globally and according to neighborhood-level SES. Using multivariable logistic regression, adjusted odds ratios (OR) were computed to obtain VE (1-OR). Adjusted VE of 2 doses was 62% (95% confidence interval [CI]: 37%–77%) and 94% (95%CI: 52%–99%) in preventing AGE and RVGE hospitalization, respectively. Stratified analyses according to SES showed that children living in neighborhoods with higher rates of low-income families had significantly lower VE against AGE hospitalizations compared to neighborhoods with lower rates of low-income families (30% vs. 78%, p = 0.027). Our results suggest that the rotavirus vaccine is highly effective in preventing severe gastroenteritis in young children, particularly among the most well-off. SES seems to influence rotavirus VE, even in a high-income country like Canada. Further studies are needed to determine factors related to lower rotavirus VE among socioeconomically disadvantaged groups.

The risk of intussusception following monovalent rotavirus vaccination in England: A self-controlled case-series evaluation

ObjectiveTo investigate the risk of intussusception after monovalent rotavirus vaccine (RV1) given to infants aged 2 and 3 months in England. MethodsHospital Episode Statistics (HES) were used to identify infants aged 48–183 days admitted between 11/03/2013 and 31/10/2014 with intussusception. Diagnosis was confirmed from medical records and HES procedure codes. Vaccination status was obtained from general practitioners. The risk of admission within 1–7 and 8–21 days of vaccination was analysed using the self-controlled case-series (SCCS) method with age effect adjustment by including historical data before RVI introduction in July 2013. ResultsA total of 119 cases were identified during the study period and intussusception confirmed in 95 of whom 39 were vaccinated 1–21 days before onset. An increased relative incidence (RI) in this period was found, 4.53 (95% confidence interval 2.34–8.58) and 2.60 (1.43–4.81) respectively after the 1st and 2nd doses with an attributable risk of 1.91 and 1.49 per 100,000 doses respectively. The peak risk was 1–7 days after the first dose, RI 13.81 (6.44–28.32), with an estimated 93% of the 15 cases being vaccine-attributable. Mean interval between onset and admission, and clinical features were similar between vaccine-associated and background cases. Despite intussusception being a contraindication to rotavirus vaccination, 10 infants received a further dose; none had a recurrence. The RIs in a meta-analysis combing our results with Australia, Mexico, Brazil and Singapore using RV1, a 2, 4 month schedule and SCCS gave pooled RI estimates of 2.35 (1.45–3.8) and 1.77 (1.29–2.43) in the 21 day period after the 1st and 2nd doses, respectively. The earlier age at the 2nd dose in England did not affect the risk. ConclusionWe estimate that the RVI programme causes around 21 intussusception admissions annually in England but, since it prevents around 25,000 gastro-intestinal infection admissions, its benefit/risk profile remains strongly positive.

Delayed Dosing of Oral Rotavirus Vaccine Demonstrates Decreased Risk of Rotavirus Gastroenteritis Associated With Serum Zinc: A Randomized Controlled Trial.

Rotavirus is the world's leading cause of childhood diarrheal death. Despite successes, oral rotavirus vaccines are less effective in developing countries. In an urban slum of Dhaka, we performed active diarrhea surveillance to evaluate monovalent G1P[8] rotavirus vaccine (RV1) efficacy and understand variables contributing to risk of rotavirus diarrhea (RVD). We performed a randomized controlled trial of monovalent oral rotavirus vaccine (RV1). Seven hundred healthy infants received RV1 or no RV1 (1:1) using delayed dosing (10 and 17 weeks) and were followed for 1 year. Intensive diarrhea surveillance was performed. The primary outcome was ≥1 episode of RVD. Nutritional, socioeconomic, and immunologic factors were assessed by logistic regression best-subsets analysis for association with risk of RVD and interactions with vaccine arm. Incidence of all RVD was 38.3 cases per 100 person-years. Per-protocol RV1 efficacy was 73.5% (95% confidence interval [CI], 45.8%-87.0%) against severe RVD and 51% (95% CI, 33.8%-63.7%) against all RVD. Serum zinc level (odds ratio [OR], 0.77; P = .002) and lack of rotavirus immunoglobulin A (IgA) seroconversion (OR, 1.95; P = .018) were associated with risk of RVD, independent of vaccination status. Water treatment and exclusive breastfeeding were of borderline significance. Factors not associated with RVD included height for age at 10 weeks, vitamin D, retinol binding protein, maternal education, household income, and sex. In an urban slum with high incidence of RVD, the efficacy of RV1 against severe RVD was higher than anticipated in the setting of delayed dosing. Lower serum zinc level and lack of IgA seroconversion were associated with increased risk of RVD independent of vaccination. NCT01375647.

Predictors of Uptake and Timeliness of Newly Introduced Pneumococcal and Rotavirus Vaccines, and of Measles Vaccine in Rural Malawi: A Population Cohort Study

BackgroundMalawi introduced pneumococcal conjugate vaccine (PCV13) and monovalent rotavirus vaccine (RV1) in 2011 and 2012 respectively, and is planning the introduction of a second-dose measles vaccine (MV). We assessed predictors of availability, uptake and timeliness of these vaccines in a rural Malawian setting.MethodsCommencing on the first date of PCV13 eligibility we conducted a prospective population-based birth cohort study of 2,616 children under demographic surveillance in Karonga District, northern Malawi who were eligible for PCV13, or from the date of RV1 introduction both PCV13 and RV1. Potential predictors of vaccine uptake and timeliness for PCV13, RV1 and MV were analysed respectively using robust Poisson and Cox regression.ResultsVaccine coverage was high for all vaccines, ranging from 86.9% for RV1 dose 2 to 95.4% for PCV13 dose 1. Median time delay for PCV13 dose 1 was 17 days (IQR 7–36), 19 days (IQR 8–36) for RV1 dose 1 and 20 days (IQR 3–46) for MV. Infants born to lower educated or farming mothers and those living further away from the road or clinic were at greater risk of being not fully vaccinated and being vaccinated late. Delays in vaccination were also associated with non-facility birth. Vaccine stock-outs resulted in both a delay in vaccine timeliness and in a decrease in completion of schedule.ConclusionDespite high vaccination coverage in this setting, delays in vaccination were common. We identified programmatic and socio-demographic risk factors for uptake and timeliness of vaccination. Understanding who remains most vulnerable to be unvaccinated allows for focussed delivery thereby increasing population coverage and maximising the equitable benefits of universal vaccination programmes.

Impact of Rotavirus Vaccination on Diarrheal Hospitalizations in Children Aged

Monovalent rotavirus vaccine was introduced in the routine public health immunization program in Lusaka, Zambia, in January 2012 and was rolled out countrywide in November 2013. We examined the effect of rotavirus vaccination on hospitalization for all-cause acute gastroenteritis (AGE) and rotavirus-specific AGE at a large referral hospital in Lusaka. Data were derived from ongoing hospital-based AGE surveillance from January 2009 to December 2014. Pre-rotavirus vaccine introduction (2009-2011) and post-rotavirus vaccine introduction (2013-2014) periods were compared for annual changes in hospitalizations for AGE and rotavirus; 2012 was excluded as a transition year. Hospital administrative discharge data were used to compare trends in all-cause diarrhea discharges and in-hospital diarrhea deaths captured by HIMS pre- and post-rotavirus vaccine introduction. Between January 2009 and December 2014, 5937 children <5 years of age presenting with AGE had their stools collected and tested for rotavirus by enzyme immunoassay. The rotavirus positivity rate declined from 40.1% (449/1121) in prevaccine years to 30.2% (250/828;P< .001) in 2013 and 24.7% (157/635;P< .001) in 2014. The greatest reduction was noted in infants, with the rotavirus positivity rate in this age group declining from 40.9% in prevaccine years to 34.0% (P= .009) in 2013 and 26.2% (P< .001) in 2014. Following rotavirus vaccine introduction, seasonal peaks of rotavirus and all-cause AGE were dwarfed. From HIMS data, compared to the prevaccine era, reductions of 18%-29% in all-cause diarrhea hospitalizations and 27%-33% in-hospital diarrhea deaths among children <1 year of age were observed in 2013 and 2014. We observed a significant reduction in AGE-associated in-hospital morbidity and mortality following rotavirus vaccine introduction. The greatest reduction was seen in infants <1 year who accounted for 84.4% of rotavirus hospitalizations prior to vaccine introduction.

Sustained Effectiveness of Rotavirus Vaccine Against Very Severe Rotavirus Disease Through the Second Year of Life, Bolivia 2013-2014.

In Bolivia, monovalent rotavirus vaccine was introduced in 2008 and a previous evaluation reported a vaccine effectiveness (VE) of 77% with 2 doses of vaccine in children aged <3 years. This evaluation sought to determine if rotavirus vaccine provided protection through the second year of life against circulating genotypes. A case-control study was performed in 5 hospitals from April 2013 to March 2014. Among enrolled participants who met study criteria and had rotavirus stool testing performed and vaccine status confirmed, we calculated VE using a logistic regression model. Subgroup analyses were performed among children aged <1 year and those aged ≥1 year, among children with severe diarrhea (Vesikari score ≥11) and very severe diarrhea (Vesikari score ≥15), and among G and P strains with at least 40 specimens. A total of 776 children were enrolled. For children <1 year and ≥1 year of age with severe diarrhea, VE for 2 doses was 75% (95% confidence interval [CI], 46%-88%) and 53% (95% CI, 9%-76%), respectively. For children <1 year and ≥1 year of age with very severe diarrhea, VE for 2 doses was 80% (95% CI, 44%-93%) and 74% (95% CI, 35%-90%), respectively. Genotype-specific analysis demonstrated similar VE for the 4 most common G and P types (G3, G9, P[6] and P[8]). A monovalent rotavirus vaccine remains effective against a broad range of circulating strains as part of a routine immunization program >5 years after its introduction in Bolivia. Although VE appears to wane in children aged ≥1 year, it still provides significant protection, and does not wane against severe disease.

Early Evidence of Impact of Monovalent Rotavirus Vaccine in Togo.

Togo introduced monovalent rotavirus vaccine starting 19 June 2014. We compared all-cause acute gastroenteritis (AGE) hospitalizations and rotavirus-associated hospitalizations during the prevaccine period (July 2008-June 2014) to 1 year after vaccine introduction (July 2014-June 2015). The proportion of children with AGE who tested positive for rotavirus declined from 53% (645/1223) in prevaccine years to 36% (68/187) in the postvaccine year (P< .01). The decline only occurred in children <1 year of age who were eligible for vaccination and was greatest during the rotavirus season months, supporting that it was associated with vaccine implementation.

Effectiveness of Monovalent Rotavirus Vaccine After Programmatic Implementation in Botswana: A Multisite Prospective Case-Control Study

Botswana introduced monovalent G1P rotavirus vaccine (RV1) in July 2012, providing one of the first opportunities to assess the effectiveness of routine RV1 vaccination in a high-burden setting in Africa. We sought to determine the effectiveness of RV1 against rotavirus diarrhea hospitalization using a case-control evaluation. Vaccine age-eligible children <5 years of age admitted with diarrhea at 4 hospitals in Botswana were enrolled from June 2013 to April 2015. Card-confirmed vaccine history was compared between case patients (children with laboratory-confirmed rotavirus diarrhea) and nonrotavirus "test-negative" diarrhea controls. Vaccine effectiveness (VE) was computed using unconditional logistic regression models adjusting for age, birth month/year, and hospital. Sequence-based genotyping was performed on antigen-positive samples. Among 242 case patients and 368 controls, 82% (199/242) and 92% (339/368), respectively, had received ≥1 doses of RV1. Effectiveness of a full series (2 doses) of RV1 against rotavirus diarrhea requiring hospitalization was 54% (95% confidence interval [CI], 23%-73%); 1 dose of RV1 was 48% (95% CI, 1%-72%) effective. Effectiveness was 59% (95% CI, 4%-83%) against rotavirus caused by G2P, the most common (37%) circulating genotype. However, the effectiveness of 2 RV1 doses was significantly higher in children with no undernutrition (VE, 75% [95% CI, 41%-89%]), compared to those with moderate or severe undernutrition (VE, -28% [95% CI, -309% to 60%]) (P= .02). Routine RV1 vaccination in Botswana showed effectiveness similar to that in clinical trials in Africa, including against a serotype fully heterotypic to the vaccine. Undernutrition may in part explain the lower rotavirus VE in low-income settings.

Impact of Rotavirus Vaccination on Hospitalizations and Deaths From Childhood Gastroenteritis in Botswana.

A monovalent human rotavirus vaccine (RV1) was introduced in Botswana in July 2012. We assessed the impact of RV1 vaccination on childhood gastroenteritis-related hospitalizations and deaths in 2013 and 2014. We obtained data from registers of 4 hospitals in Botswana on hospitalizations and deaths from gastroenteritis, regardless of cause, among children <5 years of age. Gastroenteritis hospitalizations and deaths during the prevaccine period (January 2009-December 2012) were compared to the postvaccine period (January 2013-December 2014). Vaccine coverage was estimated from data collected through a concurrent vaccine effectiveness study at the same hospitals. By December 2014, coverage with ≥1 dose of RV1 was an estimated 90% among infants <1 year of age and 76% among children 12-23 months of age. In the prevaccine period, the annual median number of gastroenteritis-related hospitalizations in children <5 years of age was 1212, and of gastroenteritis-related deaths in children <2 years of age was 77. In the postvaccine period, gastroenteritis-related hospitalizations decreased by 23% (95% confidence interval [CI], 16%-29%) to 937, and gastroenteritis-related deaths decreased by 22% (95% CI, -9% to 44%) to 60. Declines were most prominent during the rotavirus season (May-October) and among infants <1 year of age, with reductions of 43% (95% CI, 34%-51%) in gastroenteritis hospitalizations and 48% (95% CI, 11%-69%) in gastroenteritis deaths. Following introduction of RV1 into the national immunization program, significant declines in hospitalizations and deaths from gastroenteritis were observed among children in Botswana, suggestive of the beneficial public health impact of rotavirus vaccination.

Impact and Effectiveness of Monovalent Rotavirus Vaccine Against Severe Rotavirus Diarrhea in Ghana.

Ghana was among the first African nations to introduce monovalent rotavirus vaccine (RV1) into its childhood immunization schedule in April 2012. We aimed to assess the impact of vaccine introduction on rotavirus and acute gastroenteritis (AGE) hospitalizations and to estimate vaccine effectiveness (VE). Using data from 2 teaching hospitals, monthly AGE and rotavirus admissions by age were examined 40 months before and 31 months after RV1 introduction using interrupted time-series analyses. From January 2013, we enrolled children <2 years of age who were eligible for RV1 from a total of 7 sentinel sites across the country. To estimate VE, we fit unconditional logistic regression models to calculate odds ratios of vaccination by rotavirus case-patient status, controlling for potential confounders. Vaccine coverage ranged from 95% to 100% for dose 1 and 93% to 100% for dose 2. In the first 3 years after vaccine introduction, the percentage of hospital admissions positive for rotavirus fell from 48% in the prevaccine period to 28% (49% adjusted rate reduction; 95% confidence interval [CI], 32%-63%) postvaccination among <5-year-olds. With high vaccine coverage, it was not possible to arrive at robust VE estimates; any-dose VE against rotavirus hospitalization was estimated at 60% (95% CI, -2% to 84%;P= .056). Results from the first 3 years following RV1 introduction suggest substantial reductions of pediatric diarrheal disease as a result of vaccination. Our VE estimate is consistent with the observed rotavirus decrease and with efficacy estimates from elsewhere in sub-Saharan Africa.

Impact and Effectiveness of Monovalent Rotavirus Vaccine in Armenian Children.

The Republic of Armenia was 1 of the 2 earliest countries in the Newly Independent States to introduce rotavirus vaccine into its national immunization program to reduce the burden of rotavirus disease (documented to cause 38% of acute gastroenteritis hospitalizations [AGE] among children aged <5 years). In November 2012, RV1 (Rotarix) was introduced for Armenian infants at ages 6 and 12 weeks. The established active surveillance system at 2 hospitals in the capital, Yerevan, whereby children aged <5 years hospitalized for AGE have stool sample tested for rotavirus antigen, was used to assess trends in rotavirus hospitalizations. Immunization records on children enrolled after vaccine introduction were obtained from clinics, and vaccine effectiveness (VE) was estimated using children with AGE who test negative for rotavirus as controls for the rotavirus-positive cases. Among infants, rotavirus hospitalizations were reduced by 48% within the first year after introduction, and by ≥75% in years 2 and 3 following introduction. Reductions of ≥30% in other young children too old to have been vaccinated suggest additional benefit through indirect protection; overall in year 3, rotavirus hospitalizations were reduced by 69% among children aged <5 years. The overall VE of 2 RV1 doses in protecting against rotavirus hospitalization (any severity) was 62% (95% confidence interval [CI], 36%-77%) among children aged 6-23 months; 68% (95% CI, 24%-86%) among those aged 6-11 months, and 60% (95% CI, 20%-80%) in children aged 12-23 months. Against more severe rotavirus disease, VE was 79% (95% CI, 55%-90%) and similarly high in both age groups. RV1 is effective in young Armenian children and substantially reduced rotavirus hospitalizations shortly after introduction.