Haitao Huang1, Ping Gao2, Zhigang Gao3, Lijuan Wang4, Baoyun Hao4, Yong Liu3, Aaimin Yang5, Peng Liu3, Liru Guo3, Ying Zhang3. 1. Expanded Program on Immunization Department, Tianjin Center for Disease Control and Prevention, Tianjin, People's Republic of China. Electronic address: huanghaitao2009jmk@126.com. 2. Institute of Medical Support Technology, Academy of Military Sciences, Tianjin, People's Republic of China. 3. Expanded Program on Immunization Department, Tianjin Center for Disease Control and Prevention, Tianjin, People's Republic of China. 4. Expanded Program on Immunization Department, Binhai Center for Disease Control and Prevention, Tianjin, People's Republic of China. 5. Division of Epidemiology and Biostatistics, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region.
Abstract
BACKGROUND: A big pertussis outbreak occurred in a primary school with high vaccination coverage in northern China. An investigation was carried out in order to calculate the attack rate and identify the risk factors. METHODS: Between May 12 and July 29, an investigation was carried out in the primary school, which included 383 students and 27 teachers. Three definitions were used to distinguish the cases: confirmed, epidemiologically linked and suspected cases. A total of 232 blood samples were collected and examined by ELISA among healthy children in another primary school. RESULTS: A total of 138 suspected pertussis cases were counted, of which 116 students were confirmed. The attack rate among students was as high as 30.29%. The pertussis outbreak lasted 88 days, and had quaternary cases of transmission. Migrant children were almost four times as likely to catch the disease as local children (p = 0.005). In addition, students who had received the last dose of pertussis vaccine more than 4 years prior were three times more likely of becoming ill than those less than 4 years (p = 0.006). The average level of antibodies to pertussis was 30.99 IU/mL among healthy children. No statistically significant difference was observed between DTaP and DTwP (p = 0.843). CONCLUSIONS: This pertussis outbreak in a primary school with high vaccination coverage was an evidence of the pertussis resurgence in China. The major risk factor we identified was the waning of immunity in the years after pertussis vaccination. Booster vaccination for students should be given.
BACKGROUND: A big pertussis outbreak occurred in a primary school with high vaccination coverage in northern China. An investigation was carried out in order to calculate the attack rate and identify the risk factors. METHODS: Between May 12 and July 29, an investigation was carried out in the primary school, which included 383 students and 27 teachers. Three definitions were used to distinguish the cases: confirmed, epidemiologically linked and suspected cases. A total of 232 blood samples were collected and examined by ELISA among healthy children in another primary school. RESULTS: A total of 138 suspected pertussis cases were counted, of which 116 students were confirmed. The attack rate among students was as high as 30.29%. The pertussis outbreak lasted 88 days, and had quaternary cases of transmission. Migrant children were almost four times as likely to catch the disease as local children (p = 0.005). In addition, students who had received the last dose of pertussis vaccine more than 4 years prior were three times more likely of becoming ill than those less than 4 years (p = 0.006). The average level of antibodies to pertussis was 30.99 IU/mL among healthy children. No statistically significant difference was observed between DTaP and DTwP (p = 0.843). CONCLUSIONS: This pertussis outbreak in a primary school with high vaccination coverage was an evidence of the pertussis resurgence in China. The major risk factor we identified was the waning of immunity in the years after pertussis vaccination. Booster vaccination for students should be given.
Authors: Elise Tessier; Helen Campbell; Sonia Ribeiro; Nick Andrews; Julia Stowe; Margot Nicholls; Jaime Morgan; David Litt; Norman K Fry; Gayatri Amirthalingam Journal: Euro Surveill Date: 2021-03