Molecular characterization of measles viruses in China: Circulation dynamics of the endemic H1 genotype from 2011 to 2017

Abstract

Due to the Expanded Program on Immunization (EPI) and supplementary immunization activities (SIAs) in China, the incidence of measles in China has decreased extensively. The incidence reached its lowest levels in contemporary history in 2012 and 2017, with incidence rates of 4.6 and 4.3 per million population, respectively. However, more than 147,000 measles cases were reported from 2013 to 2016. Furthermore, the proportions of cases in infants < 8 months and adults have been increasing since 2013, representing a considerable challenge for measles elimination in China. A total of 14,868 measles viruses were isolated from confirmed measles cases from 2011 to 2017, of which 14,631 were identified as the predominant endemic genotype, H1; 87 were identified as genotype A viruses that were vaccine associated strains; and 150 were identified as non-H1 genotype viruses. The non-H1 genotype viruses included 62 D8 viruses, 70 D9 viruses, 3 D11 viruses, 14 B3 viruses, and 1 G3 virus, which were identified as imported or import-related viruses that caused sporadic cases or small outbreaks. Most of the transmission chains detected during the period 2011–2012 were interrupted and were followed by many new transmission chains of unknown origin that spread, causing a large measles resurgence in China during 2013–2016. After 4 years of measles resurgence and continuous implementation of the routine immunization program and SIAs, the population immunity reached a sufficiently high level to interrupt most of the transmission chains; only a few strains survived, which continued to be sporadically detected in China in 2017. In the present study, the results from the combined epidemiological and molecular virological data demonstrated the great progress towards measles elimination in China by the further analysis of circulation dynamics for the endemic H1 genotype measles virus from 2011 to 2017. And this study accumulated critical baseline data on circulating wild-type measles viruses in China and provides comprehensive information to the world. These comprehensive baseline data provide evidence to support measles elimination in the future, not only in China but also in other countries worldwide. In addition, the information will be very useful to other countries for tracing their sources of measles cases and for identifying transmission links, which can help prevent potential measles outbreaks.

Measles Vaccine-Associated Rash Illness in China: an Emerging Issue in the Process of Measles Elimination

“…The high-quality surveillance of the MSS and CMLN provided strong support for measles elimination programs by providing both epidemiological and laboratory data in China. According to the national measles surveillance program in China, the clinical samples of about 10% of measles surveillance cases are collected for MeV genotyping identification every year based on the principle of continuity and representativeness of measles surveillance in each province (18). Cases of VARI and wild-type measles were confirmed by MeV genotyping based on the N-450 nucleotide sequence in the laboratories of the CMLN (11,19). In this study, VARI and genotype H1 wild-type measles cases with complete epidemiological, clinical, and genotyping information in 2011 to 2018 were collected to analyze the characteristics of VARI.…”

“…However, measles vaccine-associated rash illness (VARI) was detected during the measles case-based surveillance (9)(10)(11)(12). VARI is a reaction that occurs after measles vaccination in 5 to 15% of recipients (13).…”

Progress Toward Measles Elimination — China, January 2013–June 2019

“…Until 2019, almost all (98.9%) cases that had a measles virus genotype result were found to be the indigenous genotype H1. However, in the first half of 2019, this pattern changed: 82% of genotyped measles viruses were found to be import-associated genotypes B3 or D8 ( Table1 ) ( 5 ).…”

Measles outbreak in an office building in the crowded Metropolis of Beijing, China

“…If isolates were not obtained, then N450 sequences were obtained directly from for further genotyping. The methods on virus isolation and genomic sequencing analyses were described in these papers [15–18].…”