Transmission Pattern of Measles Virus Circulating in China During 1993–2021: Genotyping Evidence Supports That China Is Approaching Measles Elimination

Abstract

Background To provide useful insights into the measles elimination progress in China, measles surveillance data was reviewed, and the transmission patterns of measles viruses circulating in China during 1993–2021 were analyzed. Methods Measles incidence data from the National Notifiable Disease Reporting System of the China Center for Disease Control and Prevention was analyzed. A total of 17,570 strains were obtained from 30 of 31 provinces in mainland China during 1993–2021. The recommended genotyping window was amplified. Genotyping analysis was conducted in comparison with the reference strains. Furthermore, phylogenetic analyses were performed to identify genetic relationships among different lineages within the genotypes. Results With high coverage of routine immunization and intensive supplementary immunization activities, measles incidence has shown a downward trend since 1993, despite two resurgences, reaching a historic low level in 2020–2021 (average 0.5 per million). During 1993–2021, nine genotypes including domestic genotype H1, imported genotypes B3, D4, D8, D9, D11, G3, and H2, and vaccine-associated genotype A were identified. Among them, genotype H1 strain circulated endemically in China for over 25 years; the last strain was detected in Yunnan province in September 2019. Multiple imported genotypes were identified since 2009 showing different transmission patterns. Since April 2020, no imported strains have been detected, while vaccine-associated genotype A continues to be detected. Conclusions The evidence of low incidence during 2020–2021 and virological surveillance data in this study confirmed that China is currently approaching measles elimination.

China has the momentum to eliminate measles

“…The H1 genotype that circulated endemically in China for more than 25 years was last detected in Yunnan Province in September 2019. 7 In 1990 there were 19 circulating measles genotypes, while in 2018 this was reduced to four (B3, D4, D8 and H1). 8 If H1 extinction is confirmed, then this is huge step forward towards global measles virus eradication.…”