Tara Kerin

Association between pentavalent rotavirus vaccine and severe rotavirus diarrhea among children in Nicaragua.

CONTEXT Pentavalent rotavirus vaccine (RV5), a live, oral attenuated vaccine, prevented 98% of severe rotavirus diarrhea in a trial conducted mainly in Finland and the United States. Nicaragua introduced RV5 in 2006, providing the first opportunity to assess the association between vaccination and rotavirus disease in a developing country. OBJECTIVE To assess the association between RV5 vaccination and subsequent rotavirus diarrhea requiring overnight admission or intravenous hydration. DESIGN, SETTING, AND PARTICIPANTS Case-control evaluation in 4 hospitals in Nicaragua from June 2007 to June 2008. Cases were children age-eligible to receive RV5 who were admitted or required intravenous hydration for laboratory-confirmed rotavirus diarrhea. For each case (n = 285), 1 to 3 neighborhood (n = 840) and hospital (n = 690) controls were selected. MAIN OUTCOME MEASURES Primary outcome was the association of RV5 and rotavirus diarrhea requiring overnight admission or intravenous hydration in the emergency department. Secondary analysis further classified disease as severe and very severe. We computed the matched odds ratio of vaccination in cases vs controls. Vaccine effectiveness was estimated using the formula 1 - matched odds ratio x 100%. RESULTS Of the 285 rotavirus cases, 265 (93%) required hospitalization; 251 (88%) received intravenous hydration. A single rotavirus strain (G2P[4]) was identified in 88% of the cases. Among cases and controls, respectively, 18% and 12% were unvaccinated, 12% and 15% received 1 dose of RV5, 15% and 17% received 2 doses, and 55% and 57% received 3 doses. Vaccination with 3 doses was associated with a lower risk of rotavirus diarrhea requiring overnight admission or intravenous hydration (odds ratio [OR], 0.54; 95% confidence interval [CI], 0.36-0.82). Of the 285 rotavirus cases, 191 (67%) were severe and 54 (19%) were very severe. A progressively lower risk of severe (OR, 0.42; 95% CI, 0.26-0.70) and very severe rotavirus diarrhea (OR, 0.23; 95% CI, 0.08-0.61) was observed after RV5 vaccination. Thus, effectiveness of 3 doses of RV5 against rotavirus disease requiring admission or treatment with intravenous hydration was 46% (95% CI, 18%-64%); against severe rotavirus diarrhea, 58% (95% CI, 30%-74%); and against very severe rotavirus diarrhea, 77% (95% CI, 39%-92%). CONCLUSION Vaccination with RV5 was associated with a lower risk of severe rotavirus diarrhea in children younger than 2 years in Nicaragua but to a lesser extent than that seen in clinical trials in industrialized countries.

Effectiveness of rotavirus vaccination against childhood diarrhoea in El Salvador: case-control study

Objective To evaluate the effectiveness of a monovalent rotavirus vaccine against severe rotavirus disease and to assess its impact on diarrhoea in children aged less than 2 years after national introduction in El Salvador, a low-middle income country in Central America. Design Matched case-control study. Setting Seven hospitals in cities across El Salvador, January 2007 to June 2009. Participants 323 children aged less than 2 years admitted with laboratory confirmed rotavirus diarrhoea and 969 healthy controls matched for age and neighbourhood. Main outcome measure Effectiveness of rotavirus vaccination ((1–adjusted odds ratio of vaccination)×100) against rotavirus diarrhoea requiring hospital admission. Results Cases and controls were similar for breast feeding, premature birth, maternal education, and socioeconomic variables. G1P[8] strains were identified in 92% of rotavirus cases. Effectiveness of two doses of vaccination against diarrhoea requiring hospital admission was 76% (95% confidence interval 64% to 84%). Protection was significantly lower (P=0.046) among children aged 12 months or more (59%, 27% to 77%) compared with children aged 6-11 months (83%, 68% to 91%). One dose of vaccine was 51% (26% to 67%) effective. At the sentinel hospitals, all admissions for diarrhoea among children under 5 declined by 40% in 2008 and by 51% in 2009 from the prevaccine year 2006. Conclusions A monovalent rotavirus vaccine was highly effective against admissions for rotavirus diarrhoea in children aged less than 2 years in El Salvador and substantially reduced the number of such admissions in this low-middle income setting. The impact on disease epidemiology after vaccination, particularly among older children, warrants future attention.

United States rotavirus strain surveillance from 2005 to 2008: genotype prevalence before and after vaccine introduction.

Background: A live, attenuated rotavirus vaccine, RotaTeq®, was approved in 2006 for immunization of infants in the United States. To monitor the distribution of rotavirus genotypes before and after vaccine introduction, the Centers for Disease Control and Prevention conducted strain surveillance with the National Rotavirus Strain Surveillance System. Methods: Over 3 rotavirus seasons, 2005–2006, 2006–2007, and 2007–2008, National Rotavirus Strain Surveillance System laboratories collected rotavirus-positive stool specimens and submitted them to the Centers for Disease Control and Prevention. Rotavirus strains were G- and P-genotyped by multiplex reverse transcription-polymerase chain reaction or nucleotide sequencing. Results: During 2005–2006 and 2006–2007 seasons, G1 was the dominant G-type but in the 2007–2008 season, G3 replaced G1 as the most frequently detected strain. Four genotypes, G1P[8], G2P[4], G3P[8], and G9P[8] were detected in every season. Uncommon strains observed during the study period were G2P[8], G1P[6], G2P[6], G4P[6], G1P[4], G3P[9], G12P [6], and G12P[8]. The mean age of rotavirus cases in the 2007–2008 season increased significantly in patients less than 3 years old compared with the 2 previous seasons. Conclusions: The increased overall prevalence of G3P [8] strains in 2007–2008, the first rotavirus season with reasonable rotavirus vaccine coverage, was consistent with Australian reports of G3 dominance following RotaTeq introduction. However, these strain changes in both countries have occurred in the context of large declines in severe rotavirus disease and we cannot rule out that they are simply the result of naturally occurring changes in rotavirus strain prevalence. These findings underscore the need for careful monitoring of strains to assess possible vaccine pressure-induced changes and vaccine effectiveness against various rotavirus genotypes.

Rotavirus Antigenemia in Patients with Acute Gastroenteritis

Although rotavirus infections are generally considered to be confined to the intestine, recent reports suggest that extraintestinal disease occurs. We studied whether rotavirus infection was associated with antigenemia during a major outbreak of gastroenteritis in the Kingston metropolitan area, during July-August 2003. Rotavirus antigen was identified in 30 of 70 acute-phase serum samples (including from 2 deceased individuals) but in only 1 of 53 control samples. Serum antigen levels were inversely associated with time since symptom onset and were directly associated with antigen levels in stool (P = .02). Serum antigen levels were significantly elevated during primary infections (acute-phase serum immunoglobulin G [IgG] titers, <25), compared with those in subsequent infections (acute-phase serum IgG titers, > or = 25) (P = .02). Antigenemia was common in this outbreak and might provide a mechanism to help explain rare but well-documented reports of findings of extraintestinal rotavirus. In situations in which stool samples are not readily available (i.e., patients with severe dehydration or those recently recovered or deceased), serum testing by enzyme immunoassay offers a new and practical diagnostic tool.

Genomic characterization of human rotavirus G8 strains from the African rotavirus network: relationship to animal rotaviruses.

Global rotavirus surveillance has led to the detection of many unusual human rotavirus (HRV) genotypes. During 1996–2004 surveillance within the African Rotavirus Network (ARN), six P[8],G8 and two P[6],G8 human rotavirus strains were identified. Gene fragments (RT‐PCR amplicons) of all 11‐gene segments of these G8 strains were sequenced in order to elucidate their genetic and evolutionary relationships. Phylogenetic and sequence analyses of each gene segment revealed high similarities (88–100% nt and 91–100% aa) for all segments except for gene 4 encoding VP4 proteins P[8] and P[6]. For most strains, almost all of the genes of the ARN strains other than neutralizing antigens are related to typical human strains of Wa genogroup. The VP7, NSP2, and NSP5 genes were closely related to cognate genes of animal strains (83–99% and 97–99% aa identity). This study suggests that the ARN G8 strains might have arisen through VP7 or VP4 gene reassortment events since most of the other gene segments resemble those of common human rotaviruses. However, VP7, NSP2 (likely), and NSP5 (likely) genes are derived potentially from animals consistent with a zoonotic introduction. Although these findings help elucidate rotavirus evolution, sequence studies of cognate animal rotavirus genes are needed to conclusively determine the specific origin of those genes relative to both human and animal rotavirus strains. J. Med. Virol. 81:937–951, 2009.

Rotavirus disease burden and impact and cost-effectiveness of a rotavirus vaccination program in kenya.

BACKGROUND The projected impact and cost-effectiveness of rotavirus vaccination are important for supporting rotavirus vaccine introduction in Africa, where limited health intervention funds are available. METHODS Hospital records, health utilization surveys, verbal autopsy data, and surveillance data on diarrheal disease were used to determine rotavirus-specific rates of hospitalization, clinic visits, and deaths due to diarrhea among children <5 years of age in Nyanza Province, Kenya. Rates were extrapolated nationally with use of province-specific data on diarrheal illness. Direct medical costs were estimated using record review and World Health Organization estimates. Household costs were collected through parental interviews. The impact of vaccination on health burden and on the cost-effectiveness per disability-adjusted life-year and lives saved were calculated. RESULTS Annually in Kenya, rotavirus infection causes 19% of hospitalizations and 16% of clinic visits for diarrhea among children <5 years of age and causes 4471 deaths, 8781 hospitalizations, and 1,443,883 clinic visits. Nationally, rotavirus disease costs the health care system

G and P Types of Circulating Rotavirus Strains in the United States during 1996–2005: Nine Years of Prevaccine Data

10.8 million annually. Routine vaccination with a 2-dose rotavirus vaccination series would avert 2467 deaths (55%), 5724 hospitalizations (65%), and 852,589 clinic visits (59%) and would save 58 disability-adjusted life-years per 1000 children annually. At

Molecular characterization of a rare, human-porcine reassortant rotavirus strain, G11P[6], from Ecuador.

3 per series, a program would cost

Phylogenetic analysis of novel G12 rotaviruses in the United States: A molecular search for the origin of a new strain

2.1 million in medical costs annually; the break-even price is

Genomic characterization of human rotavirus G10 strains from the African Rotavirus Network: relationship to animal rotaviruses.

2.07 per series. CONCLUSIONS A rotavirus vaccination program would reduce the substantial burden of rotavirus disease and the economic burden in Kenya.