Introduction Of Rotavirus Vaccine Research Articles

1491. Active Norovirus Surveillance in Children Under 5 Years with Diarrhea after Rotavirus Vaccine Introduction in Argentina (2017–2019)

BackgroundAcute diarrhea is one of the leading causes of infant morbidity and mortality. Argentina introduced massive rotavirus vaccination in 2015. In several countries, this introduction has changed the distribution of enteropathogens. The decrease in the prevalence of rotavirus has been described at the expense of an increase in Norovirus (NoV) activity worldwide. The aim of this study was to analyze the role of NoV in acute diarrhea cases in outpatient children under 5 years of age and their epidemiological profile.MethodsA prospective and cross-sectional study in <5 years outpatients attended for acute diarrhea in Children’s Hospital “Dr. Ricardo Gutiérrez” in Buenos Aires, Argentina, between July 2017 and March 2019 was conducted. Active epidemiological surveillance was performed with a specific case reporting form. Stool samples were tested for NoV (RT-qPCR). Clinical and epidemiological data were recorded.ResultsA total of 252 patients were enrolled and 235 stools samples were tested. Median of age was 22.3 months (IQR: 11–30), 58.7% were male. The most frequent symptoms were fever and vomiting in 63.1% and 53%, respectively; 52% had watery diarrhea, 45.2% had moderate diarrhea according to Vesikari Scale, 95.6% were normohydrated and 22% had a household member with diarrhea. There were no immunocompromised children. A 72% had received rotavirus vaccine, 86% of them with full scheme. From samples tested, 27% (n = 63) were NoV positive. NoV was found throughout the year and the frequency of detection was higher in January and June (summer and winter in Argentina). Regarding genetic diversity the most frequent genogroup was GII (65%; 41/63) and genotype GII.P16-GII.4 Sydney (48%; 20/41). Bacterial co-infection was observed in 35%. Compared with negative cases, NoV were younger (18 vs. 20 months; P < 0.001) and were associated with higher prevalence of rotavirus vaccination (88% vs. 66%; P = 0.001). No statistically difference was found regarding to gender, clinical outcome and severity.ConclusionNoV was detected at high frequency (27%) in children presenting moderate acute diarrhea, mainly in those who received rotavirus vaccine. Regarding sporadic acute diarrhea cases in children, it is important to consider NoV as a frequent etiological agent.Disclosures All authors: No reported disclosures.

93. Trends in the Laboratory Detection of Rotavirus Before and After Implementation of Routine Rotavirus Vaccination: the United States, 2000–2018

BackgroundBefore the introduction of rotavirus vaccine in the United States in 2006, rotavirus infection was the leading cause of severe gastroenteritis among US children.MethodsTo evaluate the long-term impact of rotavirus vaccination on disease burden in the United States, CDC analyzed national laboratory testing data for rotavirus from laboratories participating in CDC’s National Respiratory and Enteric Viruses Surveillance System (NREVSS) during the pre- (2000–2006) and post-vaccine (2007–2018) periods.ResultsNationally, the median annual percentage of positive rotavirus tests declined from 25.6% (range: 25.2–29.4%) in the pre-vaccine era to 6.1% (range: 2.6–11.1%) in the post-vaccine period. When comparing the pre- and post-vaccine era, the annual peak in rotavirus positivity declined from a median of 43.1% (range: 43.8–56.3%) to a median 14.0% (range: 4.8–27.3%) while the season duration was reduced from a median of 26 weeks (range: 23–27 weeks) to 9 weeks (range: 0–18 weeks). In the post-vaccine period, a biennial pattern emerged with alternating years of low and high rotavirus activity.ConclusionThe implementation of rotavirus vaccine has dramatically reduced the disease burden and altered seasonal patterns of rotavirus in the United States; these changes have been sustained over 11 post-vaccine introduction seasons.Disclosures All Authors: No reported Disclosures.

Does rotavirus turn on type 1 diabetes?

Rotavirus (RV) remains the major cause of infantile gastroenteritis worldwide, although the advent of vaccination has substantially decreased associated mortality [1]. Recently, we observed a 15% decrease in the incidence of type 1 diabetes (T1D) in Australian 0–4-year-old children following the introduction of RV vaccination [2, 3], suggesting that RV vaccination could contribute to the primary prevention of this autoimmune disease. This finding builds on our human and animal studies implicating RV in the development of T1D in genetically susceptible children.

Influence of histo blood group antigen expression on susceptibility to enteric viruses and vaccines.

Gastroenteritis results in substantial morbidity and mortality worldwide, especially in young children in low-and-middle-income settings. Rotavirus and norovirus are the leading causes of viral gastroenteritis. Although introduction of rotavirus vaccines into childhood immunization programmes has reduced disease burden, vaccine effectiveness remains low in developing countries. Norovirus is replacing rotavirus as the most common cause of diarrhea hospitalization in settings where rotavirus vaccines are highly effective. Genetically determined host factors, such as expression of histo blood group antigens (HBGAs) are hypothesized to play key roles in susceptibility to infections and gastroenteritis caused by these virus, as well as influence vaccine take. Epidemiology studies provide strong support for virus genotype-dependent effects of host HBGA expression, specifically secretor status on susceptibility to rotavirus and norovirus. Secretor-positive persons are significantly more susceptible to gastroenteritis caused by rotavirus P[8] genotype, and to infection with the GII.4 genotype of human norovirus. There is increasing data on the role of secretor status on rotavirus vaccine take but results are currently conflicting. For analyses involving young infants, maternal HBGA status is an important factor to be considered in future studies. Genetically determined HBGA expression influences susceptibility to enteric viruses of public health importance.

Impact of rotavirus vaccination and piped water access on childhood diarrhea rates in Peru, 2005-2015

OPS 24: Drinking water contamination and children’s health, Room 411, Floor 4, August 27, 2019, 10:30 AM - 12:00 PM Background: Peru has undergone several health and infrastructure developments since 2005, including increased access to piped drinking water and national introduction of oral rotavirus vaccination. We examined whether these factors were associated with lower diarrhea rates in children under five. Methods: We fit a negative binomial model investigating the impact of rotavirus vaccination and piped water access on diarrhea rates in the 195 Peruvian provinces from 2005-2015, considering the interaction between these factors, and controlling for long-term and seasonal (El Niño) trends. We compared the “pre-(rotavirus) vaccine” (2005-2009) and “post-vaccine” (2010-2015) eras. Annual percentages of households in each province with access to piped water were analyzed in quartiles. Results: The 2005 childhood diarrhea rate was ~27 annual clinic visits per 100 children and decreased ~3% per year. Higher access to piped water was associated with significantly lower childhood diarrhea rates in the post-vaccine era only. We found no effect of the rotavirus vaccine in the lowest quartile of piped water access. Controlling for long-term trend, compared to the pre-vaccine era, the diarrhea rate was lower in the post-vaccine era by 7% (95% confidence interval (CI): 2-12%), 13% (95% CI: 7-19%), and 15% (95% CI: 10-20%) in the 2nd, 3rd, and 4th quartiles of piped water access, respectively. Diarrhea rates were significantly higher (6%, 95% CI: 4-8%) during moderate or strong El Niño events. Conclusions: Explanations for higher reductions in diarrhea rates from the pre- to post-vaccine era in provinces with better piped water access include: children without piped water may be predisposed to environmental enteric dysfunction, diminishing oral vaccine impact, and/or the etiologic patterns of diarrhea (and effectiveness of a vaccine targeting a viral pathogen) may differ by water source. Improved access to piped water and rotavirus vaccination may operate synergistically to reduce childhood clinic visits for diarrhea in Peru.

Surveillance of Rotavirus Gastroenteritis (2015-2017): Epidemiology and Circulating Rotavirus Genotypes in Pre-rotavirus Vaccine Introduction Period in Myanmar

A hospital-based prospective active surveillance for rotavirus gastroenteritis (RVGE) was conducted among hospitalised acute gastroenteritis (AGE) patients to identify the infecting rotavirus strains and to provide epidemiological information on RVGE in Myanmar. Stool samples were collected from children less than 5 years old admitted to Yangon Children’s Hospital (YCH) for AGE during January 2015 to September 2017. Collected stool samples were screened for rotavirus antigen by ELISA and genotyped by reverse transcription polymerase chain reaction (RT-PCR). Overall, 48.8% (1,167/2,393) of samples were ELISA positive for rotavirus and the most affected were children aged 6-23 months, 81.9% (956/1,167). RVGE occurred in a seasonal cycle with peak detection in the cold and dry months (November to February). As compared with non-RVGE, RVGE cases had significant higher percentage of vomiting (84.5% versus 73.0%; P&lt;0.05), fever (80.1% versus 71.8%; P&lt;0.05) and severe clinical scoring (79.4% versus 67.5%; P&lt;0.05). Genotyping revealed that G9P[8] was predominant in the year 2015 (53.3%) and 2016 (30.9%), but it was replaced in 2017 by G3P[8] (58.2%). Information from this surveillance not only highlights facts for consideration of rotavirus vaccine introduction plan in pre-vaccination era, but also provides vital baseline data for post-vaccination monitoring of vaccine impact and effectiveness.

The changes of the epidemiology and clinical characteristics of rotavirus gastroenteritis-associated convulsion after the introduction of rotavirus vaccine

Rotavirus (RV) vaccine contributed to the reduction of the hospitalization for gastroenteritis (GE)-associated convulsion whereas there were few studies investigating the vaccination rate and the reduction of the disease simultaneously. The aim of this study is to investigate the alterations of the epidemiology and clinical characteristics of RVGE-associated convulsion after the introduction of RV vaccines and evaluate the reduction of the disease in the context of the vaccination rate. This retrospective study included hospitalized patients with GE and GE-associated convulsion from 2009 to 2015. The proportion of patients with RVGE and RVGE-associated convulsion and the clinical characteristics of RVGE-associated convulsion were compared between the pre- (2009–2011) and post-vaccination periods (2013–2015). The presumptive RV vaccination rate in the subject area was also investigated. During the pre- and post-vaccination periods, 47 and 49 patients with GE-associated convulsion, and 319 and 330 with GE were enrolled, respectively. Proportions of both hospitalized patients with RVGE-associated convulsion and those with RVGE during the post-vaccination period were significantly lower than those during the pre-vaccination periods (P = 0.042 and P = 0.003). Serum sodium level was significantly lower in hospitalized patients with RVGE-associated convulsion during the post-vaccination period (P = 0.021). The presumptive RV vaccination rates were 35.9%, 45.8% and 52.6% in 2013, 2014 and 2015, respectively. The proportions of hospitalized patients with RVGE-associated convulsion as well as those with RVGE decreased after the introduction of RV vaccine. RV vaccination would be also effective for the prevention of extra-intestinal complications of the virus.

Impact of the Introduction of Rotavirus Vaccine on Hospital Admissions for Diarrhea Among Children in Kenya: A Controlled Interrupted Time-Series Analysis.

BackgroundMonovalent rotavirus vaccine, Rotarix (GlaxoSmithKline), was introduced in Kenya in July 2014 and is recommended to infants as oral doses at ages 6 and 10 weeks. A multisite study was established in 2 population-based surveillance sites to evaluate vaccine impact on the incidence of rotavirus-associated hospitalizations (RVHs).MethodsHospital-based surveillance was conducted from January 2010 to June 2017 for acute diarrhea hospitalizations among children aged <5 years in 2 health facilities in Kenya. A controlled interrupted time-series analysis was undertaken to compare RVH pre– and post–vaccine introduction using rotavirus-negative cases as a control series. The change in incidence post–vaccine introduction was estimated from a negative binomial model that adjusted for secular trend, seasonality, and multiple health worker industrial actions (strikes).ResultsBetween January 2010 and June 2017 there were 1513 and 1652 diarrhea hospitalizations in Kilifi and Siaya; among those tested for rotavirus, 28% (315/1142) and 23% (197/877) were positive, respectively. There was a 57% (95% confidence interval [CI], 8–80%) reduction in RVHs observed in the first year post–vaccine introduction in Kilifi and a 59% (95% CI, 20–79%) reduction in Siaya. In the second year, RVHs decreased further at both sites, 80% (95% CI, 46–93%) reduction in Kilifi and 82% reduction in Siaya (95% CI. 61–92%); this reduction was sustained at both sites into the third year.ConclusionsA substantial reduction in RVHs and all-cause diarrhea was observed in 2 demographic surveillance sites in Kenya within 3 years of vaccine introduction.

Diversity of Rotavirus Strains Circulating in Botswana before and after introduction of the Monovalent Rotavirus Vaccine

BackgroundGlobally, rotavirus is the leading cause of acute gastroenteritis (AGE) in children aged <5 years. Botswana introduced the monovalent rotavirus vaccine (Rotarix) in July 2012. To study the impact of this vaccine on rotavirus genotypes circulating in Botswana, a comparison of the genotypes pre-vaccination (2011–2012) and post-vaccination (2013–2018) periods was conducted. Subjects and methodsResidual samples from 284 children <5 years of age that tested positive for rotavirus by enzyme immunoassay were genotyped. One hundred and five samples were from the pre-vaccination period and 179 were from the post-vaccination period. Genotyping was performed using two multiplexed one-step reverse transcription polymerase chain reaction (RT-PCR) assays for the amplification and genotyping of rotavirus VP7 (G) and VP4 (P) genes. ResultsPrior to vaccine introduction, the predominant rotavirus circulating genotypes were G9P[8] (n = 63, 60%) and G1P[8] (n = 22, 21%). During the vaccine period, G2P[4] was the predominant genotype (n = 49, 28%), followed by G9P[8] (n = 40, 22%) and G1P[8] (n = 33, 18.5%). There was a significant decline in the prevalence of G9P[8] (p = 0.001) in the post-vaccination period. There was also a notable decline in G1P[8]. A spike in G2P[4] was observed in 2013, one year post-vaccine introduction. Rotavirus strain G3P[4] (n = 8) was only detected in the post-vaccine introduction period. In 2018 there was a marked increase in genotype G3P[8] (p = 0.0003). ConclusionsThe distribution of circulating rotavirus genotypes in Botswana changed after vaccine implementation. Further studies are needed to examine whether these changes are related to vaccination or simply represent natural secular variation.

Distribution of rotavirus genotypes in three Croatian regions among children ≤5 years of age (2012–2014)

ObjectivesRotavirus is the major cause of severe diarrhea in young children worldwide. In countries like Croatia, where rotavirus vaccine has not been introduced in the national immunization program, prospective surveillance is necessary to establish the diversity of rotavirus strains. The aim of this study was to describe the prevalence and geographical distribution of rotavirus strains in Croatia and to detect the possible emergence of novel strains. MethodsThe study was conducted among children ≤5 years of age with acute gastroenteritis at three hospitals located in different geographical regions of Croatia, during the years 2012 to 2014. Rotavirus was detected in stools using an immunochromatographic assay and then sent for further molecular analysis. ResultsGenotyping of 822 rotaviruses showed that the predominant circulating strain was G1P[8] (61.9%), followed by G2P[4] (19.5%), G1P[4] (3.9%), and G3P[8] (2.9%). A high prevalence of reassortants among common human rotavirus genotypes was detected (7.7%). Possible zoonotic reassortants were found, including G8 and G6 strains. The latter is described for the first time in Croatia. ConclusionsThis study represents pre-vaccination data that are important for decisions regarding immunization strategies in Croatia. The high prevalence of ‘common’ rotavirus strains circulating in Croatia may advocate for rotavirus vaccine introduction, but further surveillance is necessary to monitor the possible emergence of novel genotypes.

Reduction in hospitalisations for acute gastroenteritis-associated childhood seizures since introduction of rotavirus vaccination: a time-series and change-point analysis of hospital admissions in England

IntroductionThe incidence of severe childhood diarrhoea has fallen substantially following the introduction of rotavirus vaccine in the UK in July 2013. Since children with rotavirus infection may experience febrile and...

Vaccine Effectiveness against DS-1-Like Rotavirus Strains in Infants with Acute Gastroenteritis, Malawi, 2013-2015.

Atypical DS-1–like G1P[8] rotaviruses emerged in 2013 in Malawi after rotavirus vaccine introduction. Vaccine effectiveness among infants hospitalized with acute DS-1–like G1P[8] rotavirus gastroenteritis was 85.6% (95% CI 34.4%–96.8%). These findings suggest that vaccine provides protection against these strains despite their emergence coinciding with vaccine introduction.

Sustained reduction in rotavirus-coded hospitalizations in children aged

ABSTRACTThis is an extension of our previous study, which evaluated the incidence of seasonal rotavirus gastroenteritis (RVGE) hospitalizations in children aged <5 years from 2009 to 2015 in Japan. Here, we evaluated the incidence of RVGE hospitalizations in children aged <10 years during the rotavirus season (January‒June) from 2009 to 2017 in Japan, before and after the monovalent and pentavalent rotavirus vaccines were introduced in November 2011 and July 2012, using the same health insurance claims database and study methods. In children aged <5 years, the incidence of RVGE hospitalizations greatly declined in 2014 after vaccine introduction, consistent with our previous findings, and the decline was sustained until 2017. However, in children aged ≥5‒<10 years, no apparent trend for a continuous decline in RVGE hospitalizations was observed during the study period. Improved RV vaccination coverage may lead to a further reduction in severe RVGE in Japan.

Rotavirus Vaccination Coverage During a Rotavirus Outbreak Resulting in a Fatality at a Subacute Care Facility.

The introduction of rotavirus vaccine in the United States has reduced rotavirus disease burden, but outbreaks still occur. Complete-series rotavirus vaccination coverage is <75% in the United States, and it might be lower among vulnerable populations. We describe here the clinical characteristics and vaccination status of children during a rotavirus outbreak in a pediatric subacute care facility in 2017. Clinical history, signs and symptoms, and vaccination history were abstracted for the 26 patients residing in the facility during the time of the outbreak. A case-patient was defined as one who experienced 3 or more loose stools in a period of 24 hours with onset between April 17 and May 17, 2017. Stool samples from 14 resident patients were tested for rotavirus with reverse-transcription polymerase chain reaction. The median patient age at the facility was 2.9 years. Of the 26 resident patients, 22 (85%) met the case definition. One child died. Stool samples from 11 case-patients were positive according to reverse-transcription polymerase chain reaction for rotavirus. Fifteen case-patients were unvaccinated against rotavirus; 3 were partially vaccinated, and 2 were fully vaccinated. Vaccination status could not be completely determined in 2 cases. An outbreak of rotavirus affected nearly all resident patients of a subacute care facility and caused 1 death. Because of recommendations against giving rotavirus vaccine in an intensive care setting, infants who require a prolonged intensive care stay might age out of rotavirus vaccine eligibility (the first dose must be given before 15 weeks of age according to Advisory Committee on Immunization Practices recommendations). The result is a vulnerable population of unvaccinated infants who might later congregate in another care setting.

Burden of rotavirus infection in hospitalized elderly individuals prior to the introduction of rotavirus vaccination in Sweden

BackgroundRotavirus gastroenteritis (GE) in the elderly has been much less studied than in children. ObjectivesThe aim of this study was to determine the morbidity and mortality for elderly hospitalized patients with rotavirus GE prior to the introduction of rotavirus vaccination in Sweden, and to investigate the epidemiology of rotavirus genotypes in these patients. Study designAll patients 60 years or older who were hospitalized at Sahlgrenska University Hospital, Gothenburg, Sweden, and were rotavirus positive in a clinical diagnostic test from 2009 to 2016, were included.Medical records were reviewed and rotavirus genotyping real-time PCR was performed. ResultsOne hundred and fifty-nine patients were included, corresponding to an annual incidence of hospitalization due to rotavirus GE of 16/100 000 inhabitants aged 60 years or older. G2P[4] was the most common genotype, followed by G1P[8] and G4P[8]. The majority of patients had community-onset of symptoms and no or few pre-existing health disorders.Four patients (2.5%) died within 30 days of sampling. Patients with hospital-onset rotavirus GE had a longer median length of stay following diagnosis compared with patients with community-onset of symptoms (19 vs. 5 days, p = 0.001) and higher 30-day mortality (8.6% (3/35) vs. < 1% (1/124), p = 0.03). ConclusionsHospitalization due to rotavirus GE among the elderly seems to mainly affect otherwise healthy individuals and is associated with low 30-day mortality.

The Burden of Acute Diarrheal Disease in Young Hospitalized Urban South African Children Five Years After Rotavirus Vaccine Introduction: A Retrospective Descriptive Study.

Diarrheal disease is a leading cause of childhood morbidity and mortality worldwide. Multiple interventions, including rotavirus vaccination to infants since 2009, have reduced the incidence of diarrheal disease in South African children. Our study aimed to determine the burden of diarrheal disease 5 years after rotavirus vaccine introduction at a tertiary-level hospital. A retrospective review of a discharge summary database of children less than 5 years of age hospitalized with acute diarrheal illness from 2015 to 2016 at the Chris Hani Baragwanath Academic Hospital. Diarrheal disease accounted for 14.8% of hospital admissions. The incidence (per 100,000 population) was 675.8 (95% CI: 638.8-714.3) in 2015 and 612.2 (95% CI: 577.0-648.9) in 2016. The case fatality ratio was 2.9% over the study period. The median age at diagnosis was 12 months (interquartile range: 6.2-21.4) and 50.4% of cases occurred during infancy. One third of cases were underweight and/or stunted. In a multivariable analysis using logistic regression, the adjusted odds ratio (aOR) for death was higher in children with an associated acute lower respiratory tract infection (aOR: 3.7, 95% CI: 1.2-11.5; P = 0.021), HIV infection (aOR: 9.1, 95% CI: 2.6-31.6; P = 0.001), and an age of less than 6 months (aOR: 6.9, 95% CI: 2.1-22.9; P = 0.002). Sustained reductions in diarrheal disease incidence were observed 5 years post rotavirus vaccine implementation. In children hospitalized with an acute diarrheal illness, an increased risk of mortality occurs in young infants, children that are HIV infected, and those with an associated acute lower respiratory tract infection.

Diarrhea-Associated Mortality in Children Less Than 5 Years of Age in the United States, 2005-2016.

Diarrheal disease morbidity decreased after the 2006 US introduction of rotavirus vaccine. We calculated diarrheal death rates for children who were <5 years of age during 2005-2016. Death rates declined from 2.3/100,000 (2005-2006) to 1.7/100,000 (2014-2016). Declines were seen among 1- to 23-month olds, white and black children. Further exploration of the role of rotavirus vaccine in decreasing deaths among children is warranted.

Intussusception among Norwegian children: What to expect after introduction of rotavirus vaccination?

BackgroundTo reduce the risk of vaccine-associated intussusception, rotavirus vaccination in Norway was implemented under strict age limits (the first dose given by 12 weeks of age and the second dose by 16 weeks of age) in 2014. We estimated the incidence of intussusception in children <2 years old before vaccine introduction and the number of vaccine-associated cases under current and extended age limits for vaccine administration in Norway. MethodsTo estimate the baseline incidence, we validated all diagnoses in children <2 years old registered in the national hospital registry during the pre-vaccine period of 2008–2013. Using national vaccine coverage data and international estimates of intussusception risk after rotavirus vaccination, we calculated the numbers of expected vaccine-associated intussusception cases to compare with the estimated numbers of averted rotavirus cases. Uncertainty was accounted for by several scenario analyses using current and extended age limits for vaccine administration. ResultsThe pre-vaccine incidence of intussusception was 26.7 (95% CI 23.1–30.6) cases/year per 100,000 children <2 years old and 37.1 (95% CI 31.2–43.8) cases/year per 100,000 children <1 year old. In the 2016 birth cohort (approx. 60,000) vaccinated under the current age limits, 1.3 (95% CI 0.7–2.0) vaccine-associated intussusception cases were expected to occur. If age limits were extended to 16 weeks for the first vaccine dose and 24 weeks for the second dose, leading to more children vaccinated at an older age, 2.2 (95% CI 1.2–3.5) excess cases would be expected in the same cohort. Simultaneously, an estimated 1768 rotavirus hospitalizations/year in children <5 years old would be averted under current age limits, with 98 additional rotavirus hospitalizations averted under extended age limits. ConclusionsAdministering rotavirus vaccines beyond current age limits in Norway would lead to a marginal increase in the number of intussusception cases, which would be offset by the benefits of vaccination.

Trends in the Laboratory Detection of Rotavirus Before and After Implementation of Routine Rotavirus Vaccination - United States, 2000-2018.

Before the introduction of rotavirus vaccine in the United States in 2006, rotavirus infection was the leading cause of severe gastroenteritis among U.S. children (1). To evaluate the long-term impact of rotavirus vaccination on disease prevalence and seasonality in the United States, CDC analyzed national laboratory testing data for rotavirus from laboratories participating in CDC's National Respiratory and Enteric Viruses Surveillance System (NREVSS) during the prevaccine (2000-2006) and postvaccine (2007-2018) periods. Nationally, the median annual percentage of tests positive for rotavirus declined from 25.6% (range=25.2-29.4) in the prevaccine period to 6.1% (range=2.6-11.1) in the postvaccine period. When compared with the prevaccine period, the postvaccine period saw declines in the annual peak in rotavirus positivity from a median of 43.1% (range=43.8-56.3) to a median of 14.0% (range=4.8-27.3) and in the season duration from a median of 26 weeks (range=23-27) to a median of 9 weeks (range=0-18). In the postvaccine period, a biennial pattern emerged, with alternating years of low and high rotavirus activity. Implementation of the rotavirus vaccination program has substantially reduced prevalence of the disease and altered seasonal patterns of rotavirus in the United States; these changes have been sustained over 11 seasons after vaccine introduction. Ongoing efforts to improve coverage and on-time vaccination (2) can help maximize the public health impact of rotavirus vaccination.

Rotavirus Epidemiology and Vaccination Tactics

Rotavirus infection is a widespread cause of severe gastroenteritis in children in low-income countries. Specific prophylaxis in young children has become the most important means of combating severe rotavirus gastroenteritis. The review presents current data on the molecular biology and genetic diversity of rotaviruses, interaction of viral proteins with host cell receptors, molecular aspects of infectivity and pathogenesis of rotavirus infection, and the development of immunity. It addresses a new approach to the epidemiology of rotavirus infection which regards it as a manageable infection, it illustrates the specificity of the epidemic process based on data gained from extensive experience in vaccination, and summarises relevant information on the introduction of rotavirus vaccines into the international healthcare practice. The paper summarises risks associated with the use of vaccines based on the analysis of WHO statistics, scientific publications on the epidemiology of rotavirus infection, and the results of vaccination. It analyses approaches of the competent authorities of some countries to the tactics of vaccination against rotavirus infection and the WHO stance on the use of existing vaccines for the prevention of rotavirus infection. A conclusion was made that it is necessary to further improve the tactics of vaccine prevention of rotavirus infection in Russia, to study the incidence of idiopathic intussusception, and to conduct further studies aimed at characterisation of existing and newly emerging genotypes of rotavirus.