Identification and control of a poliomyelitis outbreak in Xinjiang, China.

BACKGROUND: The last case of infection with wild-type poliovirus indigenous to China was reported in 1994, and China was certified as a poliomyelitis-free region in 2000. In 2011, an outbreak of infection with imported wild-type poliovirus occurred in the province of Xinjiang. METHODS: We conducted an investigation to guide the response to the outbreak, performed sequence analysis of the poliovirus type 1 capsid protein VP1 to determine the source, and carried out serologic and coverage surveys to assess the risk of viral propagation. Surveillance for acute flaccid paralysis was intensified to enhance case ascertainment. RESULTS: Between July 3 and October 9, 2011, investigators identified 21 cases of infection with wild-type poliovirus and 23 clinically compatible cases in southern Xinjiang. Wild-type poliovirus type 1 was isolated from 14 of 673 contacts of patients with acute flaccid paralysis (2.1%) and from 13 of 491 healthy persons who were not in contact with affected persons (2.6%). Sequence analysis implicated an imported wild-type poliovirus that originated in Pakistan as the cause of the outbreak. A public health emergency was declared in Xinjiang after the outbreak was confirmed. Surveillance for acute flaccid paralysis was enhanced, with daily reporting from all public and private hospitals. Five rounds of vaccination with live, attenuated oral poliovirus vaccine (OPV) were conducted among children and adults, and 43 million doses of OPV were administered. Trivalent OPV was used in three rounds, and monovalent OPV type 1 was used in two rounds. The outbreak was stopped 1.5 months after laboratory confirmation of the index case. CONCLUSIONS: The 2011 outbreak in China showed that poliomyelitis-free countries remain at risk for outbreaks while the poliovirus circulates anywhere in the world. Global eradication of poliomyelitis will benefit all countries, even those that are currently free of poliomyelitis.

Safety of influenza A (H1N1) vaccine in postmarketing surveillance in China.

BACKGROUND: On September 21, 2009, China began administering vaccines, obtained from 10 different manufacturers, against 2009 pandemic influenza A (H1N1) virus infection in priority populations. We aimed to assess the safety of this vaccination program. METHODS: We designed a plan for passive surveillance for adverse events after immunization with the influenza A (H1N1) vaccine. Physicians or vaccination providers were required to report the numbers of vaccinees and all adverse events to their local Center for Disease Control and Prevention (CDC), which then reported the data to the Chinese CDC through the online National Immunization Information System's National Adverse Event Following Immunization Surveillance System. Data were collected through March 21, 2010, and were verified and analyzed by the Chinese CDC. RESULTS: A total of 89.6 million doses of vaccine were administered from September 21, 2009, through March 21, 2010, and 8067 vaccinees reported having an adverse event, for a rate of 90.0 per 1 million doses. The age-specific rates of adverse events ranged from 31.4 per 1 million doses among persons 60 years of age or older to 130.6 per 1 million doses among persons 9 years of age or younger, and the manufacturer-specific rates ranged from 4.6 to 185.4 per 1 million doses. A total of 6552 of the 8067 adverse events (81.2%; rate, 73.1 per 1 million doses) were verified as vaccine reactions; 1083 of the 8067 (13.4%; rate, 12.1 per 1 million doses) were rare and more serious (vs. common, minor events), most of which (1050) were allergic reactions. Eleven cases of the Guillain-Barré syndrome were reported, for a rate of 0.1 per 1 million doses, which is lower than the background rate in China. CONCLUSIONS: No pattern of adverse events that would be of concern was observed after the administration of influenza A (H1N1) vaccine, nor was there evidence of an increased risk of the Guillain-Barré syndrome.

Sero-survey of polio antibodies during wild poliovirus outbreak in southern Xinjiang Uygur Autonomous Region, China.

BACKGROUND: After being polio free for more than 10 years, an outbreak following importation of wild poliovirus (WPV) was confirmed in Xinjiang Uygur Autonomous Region, China, in 2011. METHODS: A cross-sectional study was conducted prior to supplementary immunization activities (SIAs), immediately after the confirmation of the WPV outbreak. In selected prefectures, participants aged ≤ 60 years old who visited hospitals at county-level or above to have their blood drawn for reasons not related to the study, were invited to participate in our study. Antibody titers ≥ 8 were considered positive. RESULTS: Among the 2,611 participants enrolled, 2,253 (86.3%), 2,283 (87.4%), and 1,989 (76.2%) were seropositive to P1, P2 and P3 respectively, and 1744 (66.8%) participants were seropositive to all the three serotypes. Lower antibody seropositivities and geometric mean titers were observed in children <1 year of age and in adults aged 15-39 years. CONCLUSION: Serosurveys to estimate population immunity in districts at high risk of polio importation might be useful to gauge underlying population immunity gaps to polio and possibly to guide preparedness and response planning. Consideration should be given to older children and adults during polio risk assessment planning and outbreak response.

[Review of the sudden death and death following immunization of influenza vaccine].

To evaluate the safety of influenza Type A (H1N1) vaccine by review the incidence, epidemiology characteristics of sudden death and the deaths related with immunization, especially focus on the sudden deaths after immunization of influenza Type A (H1N1) vaccine. Preliminary showed that those deaths reported as adverse events following immunization did not associated with the vaccine. Vaccination campaign according to the national immunization strategy should be carried out and appropriately respond to the emergency events should be strenghtened.

[Study on the timeliness of detection and reporting on public health emergency events in China].

OBJECTIVE: To analyze the timeliness of detection and reporting on public health emergency events, and to explore the effective strategies for improving the relative capacity on those issues. METHODS: We conducted a retrospective survey on 3275 emergency events reported through Public Health Emergency Events Surveillance System from 2005 to the first half of 2006. Developed by county Centers for Disease Control and Prevention, a uniformed self-administrated questionnaire was used to collect data, which would include information on the detection, reporting of the events. RESULTS: For communicable diseases events, the median of time interval between the occurrence of first case and the detection of event was 6 days (P25 = 2, P75 = 13). For food poisoning events and clusters of disease with unknown origin, the medians were 3 hours (P25, P75 = 16) and 1 days (P25 = 0, P75 = 5). 71.54% of the events were reported by the discoverers within 2 hours after the detection. CONCLUSION: In general, the ranges of time intervals between the occurrence, detection or reporting of the events were different, according to the categories of events. The timeliness of detection and reporting of events could have been improved dramatically if the definition of events, according to their characteristics, had been more reasonable and accessible, as well as the improvement of training program for healthcare staff and teachers.

[Study on the occupational distribution of discoverers and reporters of public health emergency events reported through Internet-based surveillance system].

OBJECTIVE: To describe the occupational distribution of staff who worked on detection and reporting on public health emergency events, and to explore the effective strategies for identification and reporting on emergency events. METHODS: We conducted a retrospective survey on 3275 emergent events reported through Public Health Emergency Events Surveillance System from 2005 to the first half of 2006. Data were collected by uniform self-administrated questionnaires by county Centers for Disease Control and Prevention, including information on events detection and reporting, etc. RESULTS: Among event discoverers, 56.40% (1847/3275) were healthcare staff, 20.58% (674/3275) were teachers, and 15.15% (496/3275) were staff from the disease control systems. Among those event reporters, 56.82% (1861/3275) were healthcare staff, 21.77% (713/3275) from disease control system and 10.75% (352/ 3275) were teachers. CONCLUSION: Healthcare staff and teachers played the most important role in detection and reporting on events. It would be favorable to improve the ability of events detection and reporting if we could enhance the training program to the relative staff in medical facilities and school settings especially at the grass root level.