Effect of rotavirus vaccine implementation on the prevalence of co‐infections with enteric viruses in Norway

Acute gastroenteritis (AGE) is a common illness in both adults and children worldwide and is caused by several microorganisms including viruses, bacteria, and parasites. Rotavirus (RV), which is the main cause of AGE, can occur as a mixed infection with other viruses. The aim of this study is to assess the molecular epidemiology of viral enteric viruses and assess RV coinfections with other enteric viruses and their influence on disease severity before and after RV vaccine introduction in children under 5 years of age. A total of 600 samples collected from children hospitalized for AGE in five large hospitals in Norway, and were analyzed for viral gastroenteritis agents by enzyme immunoassay and quantitative real‐time polymerase chain reaction (qRT‐PCR). Positive results confirmed either by Sanger sequencing or genotyped by multiplex semi‐nested RT‐PCR. In total, 243 of the 300 (81%) samples, collected from the prevaccine cohort, were positive for at least one of the four viruses tested in this study. RV was most frequently identified in 82.6% of the samples. In the postvaccine cohort, 114 of the 300 (38%) samples were positive for at least one of the viruses tested. RV found in 36.5% of the samples. Coinfections found less frequently in the postvaccine cohort. Among circulating enteric viruses in Norway, RV is the most important cause of viral gastrointestinal infection. As expected, there were fewer RV positive and fewer coinfections after RV vaccine implementation. The results provide valuable data that can aid in further evaluation of the vaccine impact

Additional file 1: of Varicella-zoster virus susceptibility and primary healthcare consultations in Norway

Univariate and multivariable analysis of varicella-zoster virus seropositivity by sex (reference: female), age group and region (reference: Oslo and Akershus) in Norway (odds ratios (OR), 95 % confidence intervals (95 % CI), and p-value). (XLSX 12 kb

Additional file 2: of Varicella-zoster virus susceptibility and primary healthcare consultations in Norway

Model fitting information (Likelihood ratios and 95 % confidence intervals (CI)). (S: Sex; R: region; A: age groups. Df: the number of parameters that differ between the two nested models; AIC: Akaike information criterion). (XLSX 10 kb

Rotavirus detection in bulk stool and rectal swab specimens in children with acute gastroenteritis in Norway

Background Bulk stool specimens are traditionally used for rotavirus detection but may be challenging to obtain from young children. Immediate and easy sampling may however be required in different situations, such as outbreak investigation. Objectives We assessed the diagnostic performance of rectal swabs compared to bulk stools for the detection of rotavirus by Enzyme Immunoassay (EIA) and multiplex semi-nested reverse transcription PCR (semi-nested RT-PCR) in children recruited through active hospital-based surveillance of acute gastroenteritis in Norway. Study design We obtained 265 paired bulk stool and rectal swab specimens from children under 5 years of age hospitalized with acute gastroenteritis (AGE). Both types of specimens were analyzed for rotavirus by EIA and semi-nested RT-PCR. In addition, VP6-spesific real-time PCR was used to evaluate the detection performance in the two specimen types. Results Concordant results were obtained in 257 (97%) paired specimens by EIA and in 248 (94%) pairs by semi-nested RT-PCR. Results of VP6-specific real-time PCR obtained from 100 pairs of specimens showed concordance in 91% of the pairs. Sensitivity and specificity for rectal swab specimens were 95% and 100% by EIA; 95% and 92% by semi-nested RT-PCR, respectively. Conclusion Both EIA and semi-nested RT-PCR showed a high accuracy, and rectal swab specimens are appropriate for rotavirus diagnosis and may be used as an alternate specimen type when collection of bulk stool is not feasible

Genetic diversity of rotavirus strains circulating in Norway before and after the introduction of rotavirus vaccination in children

Globally, rotavirus (RV) is the leading cause of acute gastroenteritis (AGE) in young children under 5 years of age. Implementation of RV vaccination is expected to result in fewer cases of RV in the target population, but it is unknown if this also results in vaccine-induced virus strain replacement. Rotarix, a monovalent vaccine based on G1P[8] RV, was introduced in Norway in the children's immunization program in September 2014. The main aim of this study was to describe the diversity of RV circulating pre and post introduction of the RV vaccine in Norway and investigate changes in genotype distribution during the first 4 years after implementation. A total of 1108 samples were collected from children under 5 years enrolled with AGE from five large hospitals in Norway and were analyzed for RV by enzyme immunoassay (EIA). All positive results were genotyped by multiplex semi-nested reverse transcription PCR for identification of G and P types. In total, 487 of the 1108 (44%) samples, collected from the enrolled children, were positive for RV by EIA method which were further genotyped. G1P[8] was found to be the most common type of RV pre and post RV vaccine implementation followed by G9P[8]. There were neither geographical nor temporal differences in genotype dominance. Also, no apparent changes were shown in the genotype distribution in the postvaccine era for years from 2015 to 2018. In 21.4% of the cases, vaccine strains were detected. Continuous RV genotype surveillance is vital for assessing the effectiveness of a vaccine program and monitoring for any emergence of vaccine-escape strains. Genotyping is also necessary to detect vaccine strains to avoid reporting false-positive cases of active RV infection in newly vaccinated cases

Genetic diversity of rotavirus strains circulating in Norway before and after the introduction of rotavirus vaccination in children

Globally, rotavirus (RV) is the leading cause of acute gastroenteritis (AGE) in young children under 5 years of age. Implementation of RV vaccination is expected to result in fewer cases of RV in the target population, but it is unknown if this also results in vaccine-induced virus strain replacement. Rotarix, a monovalent vaccine based on G1P[8] RV, was introduced in Norway in the children's immunization program in September 2014. The main aim of this study was to describe the diversity of RV circulating pre and post introduction of the RV vaccine in Norway and investigate changes in genotype distribution during the first 4 years after implementation. A total of 1108 samples were collected from children under 5 years enrolled with AGE from five large hospitals in Norway and were analyzed for RV by enzyme immunoassay (EIA). All positive results were genotyped by multiplex semi-nested reverse transcription PCR for identification of G and P types. In total, 487 of the 1108 (44%) samples, collected from the enrolled children, were positive for RV by EIA method which were further genotyped. G1P[8] was found to be the most common type of RV pre and post RV vaccine implementation followed by G9P[8]. There were neither geographical nor temporal differences in genotype dominance. Also, no apparent changes were shown in the genotype distribution in the postvaccine era for years from 2015 to 2018. In 21.4% of the cases, vaccine strains were detected. Continuous RV genotype surveillance is vital for assessing the effectiveness of a vaccine program and monitoring for any emergence of vaccine-escape strains. Genotyping is also necessary to detect vaccine strains to avoid reporting false-positive cases of active RV infection in newly vaccinated cases