Introduction: Enterovirus A71(EV-A71)-associated hand, foot, and mouth disease (HFMD) has been reported worldwide, and poses a particularly heavy burden on patients, families, and society in China. Three Chinese companies have licensed inactivated EV-A71 vaccines, all of which have demonstrated good efficacy for preventing EV-A71-associated disease in clinical trials. However, real-world performance of EV-A71 vaccine has not been evaluated. Methods: We used a test-negative design case-control study to estimate vaccine effectiveness (VE) against medically attended EV-A71-associated HFMD. Subjects were children 5 years of age and under who had been in health facilities participating in the HFMD case and virologic surveillance platforms in Beijing. Enterovirus infections were laboratory confirmed, and EV-A71 vaccination status was extracted from electronic immunization records. Children testing positive for EV-A71 were cases; controls were children testing negative for EV-A71 infection. Logistic regression was used to estimate VE. We assessed sensitivity of VE estimates to control group inclusion criteria by repeating the regression analyses with two alternative control groups. Results: A total of 2,184 HFMD patients aged 5 years and under were enrolled in the study; 24 were severe, and 2,160 were mild. For severe cases, two-dose VE estimate was 100% (95% CI: −68.1%, 100%). For mild cases, 1-dose and 2-dose adjusted VE estimates were 69.8% and 83.7%, respectively. Two-dose VE estimates varied by less than 4 percentage points regardless of control group definition. Conclusions: Our findings suggested the vaccines performed well in the real world for children 5 years of age and under in Beijing, China.

Background: To obtain the baseline data on the incidence and cost of community acquired pneumonia among under-5 children for future studies, and provide evidence for shaping China's strategies regarding pneumococcal conjugate vaccine (PCV). Methods: Three townships from Heilongjiang, Hebei and Gansu Province and one community in Shanghai were selected as study areas. A questionnaire survey was conducted to collect data on incidence and cost of pneumonia among children under 5 y old in 2012. Results: The overall incidence of clinically diagnosed pneumonia in children under 5 y old was 2.55%. The incidence in urban area was 7.97%, higher than that in rural areas (1.68%). However, no difference was found in the incidences of chest X-ray confirmed pneumonia between urban and rural areas (1.67% vs 1.23%). X-ray confirmed cases in rural and urban areas respectively accounted for 73.45% and 20.93% of all clinically diagnosed pneumonia. The hospitalization rate of all cases was 1.40%. Incidence and hospitalization rate of pneumonia decreased with age, with the highest rates found among children younger than one year and the lowest among children aged 4 (incidence: 4.25% vs 0.83%; hospitalization: 2.75% vs 0.36%). The incidence was slightly higher among boys (2.92% vs 2.08%). The total cost due to pneumonia for the participants was 1138 733 CNY. The average cost and median cost was 5722 CNY and 3540 CNY separately. Multivariate analysis showed that the only factor related to higher cost was hospitalization. Conclusions: The disease burden was high for children under 5 y old, especially the infant. PCV has not been widely used among children, and thus further health economics evaluation on introducing PCV into National Immunization Program should be conducted.

Following implementation of China's 2006-2012 Action Plan for measles elimination, which led to a nadir of measles in 2012, a resurgence started in 2013 that continued into 2014. Measles typically is a disease that mainly affects children. We investigated a community outbreak in 2014 with measles virus transmission among adults without children serving as virus reservoirs. Our investigation highlights adult susceptibility to measles. We conducted a retrospective active case search, and analyzed confirmed case data to describe person, place, and time characteristics of the outbreak. All individuals with measles with onset during the first 2 months of the outbreak were interviewed face-to-face to determine source(s) of infection and transmission route (from whom and to whom). Among the 280 cases, 220 (77.6%) were among ≥20-year-old adults, 24 (8.6%) were among 8-23 month olds, 22 (7.9%) were among <8-month-old infants, and the remaining 14 (5.9%) were among 2-19 year olds. Of the 83 cases in the early stage of the outbreak, 41 (49.4%) were acquired in the community, 24 (28.9%) were acquired nosocomially, 13 (15.7%) were acquired by family contact, and 5 were imported. Among 44 clearly determined transmission linkages, 37 (84.1%) were adult to other age-group (these include 29 adult-to-adult, seven adult-to-child, and one adult-to-infant), six were from infants to adult and children, and one was child-to-child. Outbreak response immunization activities were implemented by non-selective supplementary immunization activities, with 51.3% of targeted 5-19-year-old children and adolescents, and 30.2% of targeted 20-49-year-old adults being vaccinated. Despite high population immunity among children and adolescents following three rounds of measles vaccine supplementary immunization activities, sustained measles virus transmission still occurred among adults in this community. Adult measles immunity gaps might threaten measles elimination, highlighting the importance targeting susceptible adults during outbreak response immunization.

Introduction The current study aims to assess the performance of data mining techniques in detecting safety signals for adverse events following immunization (AEFI) using routinely obtained data in China. Four different methods for detecting vaccine safety signals were evaluated. Methods The AEFI data from 2011 to 2015 was collected for our study. We analyzed the data using four different methods to detect signals: the proportional reporting ratio (PRR), reporting odds ratio (ROR), Bayesian confidence propagation neural network (BCPNN), and multi-item gamma Poisson shrinker (MGPS). Each method was evaluated at 1–3 thresholds for positivity. To assess the performance of these methods, we used the published signal rates as gold standards to determine the sensitivity and specificity. Results The number of identified signals varied from 602 for PRR1 (with a threshold of 1) to 127 for MGPS1. When considering the common reactions as the reference standard, the sensitivity ranged from 0.9% for MGPS1/2 to 38.2% for PRR1/2, and the specificity ranged from 85.2% for PRR1 and ROR1 to 96.7% for MGPS1. When considering the rare reactions as the reference standard, PRR1, PRR2, ROR1, ROR2, and BCPNN exhibited the highest sensitivity (73.3%), while MGPS1 exhibited the highest specificity (96.9%). Discussion For common reactions, the sensitivities were modest and the specificities were high. For rare reactions, both the sensitivities and specificities were high. Our study provides valuable insights into the selection of signal detection methods and thresholds for AEFI data in China.