Distribution of rotavirus VP4 genotype and VP7 serotype among Chinese children

The Public Health Burden of Rotavirus Disease in Children Younger Than Five Years and Considerations for Rotavirus Vaccine Introduction in China

BACKGROUND

Rotavirus is the leading cause of severe diarrhea among young children worldwide. Rotavirus vaccines have demonstrated substantial benefits in many countries that have introduced vaccine nationally. In China, where rotavirus vaccines are not available through the national immunization program, it will be important to review relevant local and global information to determine the potential value of national introduction. Therefore, we reviewed evidence of rotavirus disease burden among Chinese children younger than 5 years to help inform rotavirus vaccine introduction decisions.

METHODS

We reviewed scientific literature on rotavirus disease burden in China from 1994 through 2014 in China National Knowledge Infrastructure, Wanfang and PubMed. Studies were selected if they were conducted for periods of 12 month increments, had more than 100 patients enrolled and used an accepted diagnostic test.

RESULTS

Overall, 45 reports were included and indicate that rotavirus causes ~40% and ~30% of diarrhea-related hospitalizations and outpatient visits, respectively, among children younger than 5 years in China. Over 50% of rotavirus-related hospitalizations occur by age 1 year; ~90% occur by age 2 years. Regarding circulating rotavirus strains in China, there has been natural, temporal variation, but the predominant local strains are the same as those that are globally dominant.

CONCLUSIONS

These findings affirm that rotavirus is a major cause of childhood diarrheal disease in China and suggest that a vaccination program with doses given early in infancy has the potential to prevent the majority of the burden of severe rotavirus disease.

Spread and predominance in Japan of novel G1P[8] double-reassortant rotavirus strains possessing a DS-1-like genotype constellation typical of G2P[4] strains

Rotavirus is a major cause of severe gastroenteritis in children <5 years of age worldwide, and two, live attenuated rotavirus vaccines are globally available. As rotavirus vaccines are introduced into national immunization programs, there is an increasing need to monitor circulating wild-type strains. However, few studies have systematically examined their full genotype constellation. This study was therefore undertaken to characterize the whole genotype constellation of circulating rotavirus strains in three widely-separated locations in Japan during the 2012 rotavirus season when rotavirus vaccines became available in the country for the first time. Of 107 rotavirus-positive specimens, 50 (46.7%) strains collected from all three locations possessed an unusual G1-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 constellation in which a typical G2P[4] strain appeared to have acquired its two surface protein genes from the most common G1P[8] strain. These G1P[8] double-reassortant strains were shown to possess the 11 genome segments virtually indistinguishable from each other in their nucleotide sequences and phylogenetic lineages except for two strains that underwent further intra-genotype reassortment. Successful spread to and predominance in broad locations across Japan of novel rotavirus strains possessing a genotype constellation that was previously thought not to be preferred suggests unexpected genomic flexibility of the genotype constellation.

Serotype diversity and reassortment between human and animal rotavirus strains: implications for rotavirus vaccine programs

The development of rotavirus vaccines that are based on heterotypic or serotype-specific immunity has prompted many countries to establish programs to assess the disease burden associated with rotavirus infection and the distribution of rotavirus strains. Strain surveillance helps to determine whether the most prevalent local strains are likely to be covered by the serotype antigens found in current vaccines. After introduction of a vaccine, this surveillance could detect which strains might not be covered by the vaccine. Almost 2 decades ago, studies demonstrated that 4 globally common rotavirus serotypes (G1-G4) represent >90% of the rotavirus strains in circulation. Subsequently, these 4 serotypes were used in the development of reassortant vaccines predicated on serotype-specific immunity. More recently, the application of reverse-transcription polymerase chain reaction genotyping, nucleotide sequencing, and antigenic characterization methods has confirmed the importance of the 4 globally common types, but a much greater strain diversity has also been identified (we now recognize strains with at least 42 P-G combinations). These studies also identified globally (G9) or regionally (G5, G8, and P2A[6]) common serotype antigens not covered by the reassortant vaccines that have undergone efficacy trials. The enormous diversity and capacity of human rotaviruses for change suggest that rotavirus vaccines must provide good heterotypic protection to be optimally effective.