Emergence of Erythromycin-Resistant and Pertactin- and Filamentous Hemagglutinin-Deficient Bordetella pertussis Strains — Beijing, China, 2022–2023
A recent surveillance study of Bordetella pertussis strains in Beijing, China, has revealed significant changes in the bacterium's antigens compared to vaccine strains. All 44 isolated strains shared the same antigenic profile (ptxA1/ptxC2/ptxP3/prn150/fim2-1/fim3-1/fhaB1/tcfA2/bscI2), differing from the vaccine composition. Notably, 68.2% of the strains were found to be deficient in pertactin (Prn) due to IS481 insertion, and two strains were deficient in filamentous hemagglutinin (Fha), marking the first reported cases of Fha-deficient strains in China. Additionally, all strains exhibited resistance to macrolide antibiotics. The increasing prevalence of strains with altered antigens and antibiotic resistance poses challenges for pertussis prevention and treatment. Researchers emphasize the need for ongoing surveillance and the selection of appropriate pertussis vaccines for China’s National Immunization Program to enhance the efficacy of prevention and control strategies.
For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.085


Evolutionary Diversity of Coxsackievirus A6 Causing Severe Hand, Foot, and Mouth Disease — China, 2012–2023
A study of 74 severe hand, foot, and mouth disease (HFMD) cases in China from 2012–2023 found that coxsackievirus A6 (CVA6) has emerged as the primary pathogen, particularly affecting children under 5. The CVA6 D3a sub-genotype was predominant, showing increased diversity and regional clustering over time. Limited surveillance and diagnostic challenges may contribute to underreporting of severe cases. Researchers emphasize the need for ongoing robust surveillance targeting CVA6, improved clinician training for identifying severe HFMD, and development of CVA6-targeted vaccines to prevent severe complications in vulnerable children. Enhancing surveillance and reporting is crucial to better assess and manage the evolving disease burden of severe HFMD associated with CVA6.
For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.086


Seasonal and Genetic Characteristics of Human Metapneumovirus Circulating — Henan Province, China, 2017–2023
A six-year study in Henan, China, has revealed new insights into the epidemic patterns and genetic characteristics of human metapneumovirus (HMPV), a common cause of acute respiratory infections. The research found that HMPV primarily affects children under five, with a peak positivity rate of 42.11% in November 2020, deviating from the typical spring seasonality. The study also identified a potential subtype switching pattern and the emergence of new dominant strains with genetic modifications. These findings could inform strategies for preventing and controlling HMPV infections in China and support the development of targeted vaccines and immunization policies. The study highlights the importance of ongoing surveillance to better understand the evolving epidemiology of respiratory viruses in the post-COVID-19 era.
For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.087


Epidemiological Characterization of Dengue Fever — Yunnan Province, China, 2010–2021
A comprehensive study spanning from 2010 to 2021 has charted the emergence and spread of dengue fever in China’s Yunnan Province. The research documents 14,098 cases, with a significant number being locally transmitted. A pattern of biennial outbreaks has been revealed, with the years 2013, 2015, 2017, and 2019 experiencing sharp increases in cases. The highest incidence of dengue fever is reported in areas closer to the border, particularly in Xishuangbanna, Dehong, and Lincang, highlighting the disease's trans-border nature. The demographic breakdown suggests adults aged 15–59 are most affected, with commercial service workers, farmers, and domestic workers showing higher case counts. A notable shift in disease incidence was observed after 2019, potentially linked to stringent COVID-19 control measures that inadvertently impacted the transmission of dengue as well. The temporal distribution aligns with warmer seasons, peaking from August to October. The study underscores the critical role of border surveillance and the implementation of preventive measures, such as mosquito control and sanitation practices, to mitigate the spread of dengue fever in this region. The biennial trend of dengue outbreaks emphasizes the need for persistent vigilance, particularly given the high incidence associated with imported cases from neighboring Southeast Asian countries.
For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.088


Exploration for the Priority of HIV Intervention: Modelling Health Impact and Cost-Effectiveness — Six Cities, Eastern China, 2019–2028
A newly published study using Spectrum forecasts the potential health outcomes and cost-effectiveness of expanding human immunodeficiency virus (HIV) interventions in six cities in eastern China. These interventions are vital for customizing local HIV responses in line with unique epidemiological and economic situations. The study considers 10 HIV interventions including antiretroviral therapy (ART) and oral pre-exposure prophylaxis (PrEP), comparing a Base scenario where coverage remains at 2019 levels, an Achievable scenario with substantial but realistic coverage improvements, and an Idealized scenario aiming for near-universal coverage. Results indicate that under the Achievable scenario, substantial health benefits can be achieved at reasonable costs. For instance, in Shijiazhuang, a substantial reduction in HIV infections and deaths was predicted, presenting a cost-effective context for intervention. However, in cities with higher initial ART coverage like Foshan and Ningbo, the cost per infection averted was significantly higher, suggesting poorer cost-effectiveness in scaling up interventions. The study underscores the critical role of customizing intervention strategies to each city’s specific circumstances. Policymakers are advised to adopt the Achievable scenario. The findings guide strategic resource allocation to optimize HIV responses and contribute to controlling the epidemic at a local level.
For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.089