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Objective:To analyze the molecular epidemiological characteristics of measles virus (MV) in Beijing from 2015 to 2019, and to provide laboratory basis for measles elimination.Methods:Measles virus-positive throat swab samples were collected through the Beijing Measles Laboratory network from 2015 to 2019. After the viral nucleic acid was extracted, 450 nucleotide fragments of the C terminal of the N gene of MV were amplified by RT-PCR. Nucleotide sequencing was performed for the amplified products. The phylogenetic tree was constructed with the representative strains of WHO measles virus genotype D8 genotype reference strains in China and other countries. Genotype identification was conducted and the nucleotide and amino acid homology analysis was carried out. A descriptive analysis of measles cases with D8 and B3 genotypes was conducted.Results:From 2015 to 2019, the genotypes of 546 MV were identified in the city, including 531 of H1a genotype, five vaccine strains, one of B3 genotype, and nine of D8 genotype, among which eight were epidemic strains in 2019. The homology of indigenous H1a genotype MV nucleotide and amino acid was 91.5%-100.0% and 73.6%-100.0%.In 2019, all eight cases of D8 genotype measles were adults, with two being an outbreak and the remaining six sporadic cases.Conclusions:The imported D8 genotype had become the main MV genotype in Beijing in 2019. With the decrease of measles incidence in 2019, native genotype H1a was no longer dominant, while other different genotypes were imported, forming a mixed epidemic trend. It was suggested that in the elimination of measles in Beijing, efforts should be made not only to block the transmission of local measles virus, but also to prevent and control the import and continuous transmission of non-local genotype virus, so as to avoid the risk of establishing local transmission by gradually evolving into a dominant strain.
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Objective To analyze the genotypes and the variation trend of rubella virus strains circulating in Beijing and to provide a scientific guidance for the prevention and control of rubella.Methods The viral nucleic acids were extracted from diagnostic pharyngeal swab specimens collected by Beijing rubella laboratory.The 739 nucleotides of rubella E1 gene were amplified by reverse transcription-polymerase chain reaction ( RT-PCR) .The amplified products were sequenced and analyzed.Genotypes of the rubella virus strains circulating in Beijing and variations in their nucleotides and amino acids were analyzed by comparing with those of the WHO recommended rubella virus reference strains.Results The target nucleotide se-quences of 10 rubella virus strains were obtained for molecular epidemiological study.All of the 10 strains belonged to 2B genotype and formed an independent branch according to the phylogenetic tree based on the 739 nucleotide fragments of E1 gene.Most of the nucleotide mutations occurred in the 10 strains were non-sense mutations.The amino acid sequences of the circulating strains were highly conservative.No significant mutations in the antigenic sites were identified in the rubella virus strains circulating in Beijing except that one amino acid mutation from Ser to Phe in the No.282 amino acid of E1 protein was identified in the hemag-glutination inhibition and neutralizing site of one strain.Conclusion This study indicated that the rubella virus genotype 2B epidemic strains were isolated in Beijing.
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<p><b>OBJECTIVE</b>To investigate the changes of epidemiological characteristics of measles in Beijing before and after Supplementary Immunization Campaigns (SIA) (2007-2010 vs 2011-2014) of measles-containing vaccine (MCV) among children aged between 8 months and 14 years in 2010.</p><p><b>METHODS</b>Descriptive epidemiological analysis was conducted on surveillance data of measles cases (clinical cases and laboratory confirmed cases), with the occurrence during 2007-2014, and of outbreaks, with the occurrence during 2009-2014, from National Notifiable Disease Reporting System. MapInfo geographic information system (Version 8.5) was used to illustrate the distribution of measles incidence by district. Annual measles incidence was classified into 5 groups at the same intervals between the upper and lower limits to analyze the morbidity of the different areas.</p><p><b>RESULTS</b>In total, 7 722 and 3 132 measles cases were reported during 2007-2010 and 2011-2014, with the annual incidence of 11.59 and 3.84 cases per 100 000 population, respectively. Comparing with the results during 2007-2010, total number of measles cases and average annual incidence during 2011-2014 were decreased by 59.4%, and 66.9%, respectively. Among measles cases during 2011-2014, percentage of cases aged 15 years or above were 57.7%(56/97), 62.0%(49/79), 65.5%(370/565), and 71.4% (1 707/2 391), respectively, which increased by years. During 2007-2010, the highest risk age for adults was 20-34, while 2011-2014, 5 years older: 25-39. During 2009-2010, 2011-2012, and 2013-2014, 50.3% (447/889), 30.3% (10/33), and 57.8% (201/348), respectively, of measles cases aged 8-17 months were unvaccinated by MCV. Percentages of measles cases aged 0-7 months, 8 months-14 years, 15-39 years and 40 years or above during 2013-2014, who visited hospitals 7-21 days before disease onset, were 59.8% (238/398), 49.3% (237/481), 32.2% (529/1641), and 37.6% (164/436), respectively. A total of 11 nosocomial measles outbreaks occurred during 2013-2014, which was much higher than that during 2009-2010 (2 nosocomial outbreaks). And universities accounted for the majority of outbreak settings of schools (3/4). All 11 outbreaks among grouped employees during 2009-2012 occurred in factories, restaurants, or large shopping centers, while the largest proportion (6/16) of that kind of outbreaks during 2013-2014 occurred in office buildings.</p><p><b>CONCLUSIONS</b>SIA of MCV in 2010 effectively decreased measles transmission in Beijing. But routine immunization of MCV still needed to be improved. The issue of adult measles has been a prominent problem. Hospitals, office buildings and universities were the focus of prevention of measles transmission.</p>