Progress in research of influenza vaccination in pregnant women / 中华流行病学杂志

Influenza is an acute respiratory infectious disease caused by influenza virus. Pregnancy is associated with physiologic and immunological changes that may increase the risk for influenza virus infection and influenza-related complications. Influenza vaccination is the most effective way to prevent influenza virus infection. WHO and many countries have classified pregnant women as a priority population for influenza vaccination, however, there are still many challenges for promoting influenza vaccination in pregnant women in China, influenza vaccination coverage in pregnant women remains low and some influenza vaccine package inserts list pregnancy as an absolute contraindication. In this paper, we summarize the research progress in the effects of influenza infection and influenza vaccination during pregnancy both at home and abroad, then discuss the strategies to promote influenza vaccination in pregnancy for the purpose of providing reference for the related research and policy development in China.

Performance of screening of contacts of COVID-19 cases in same flight / 中华流行病学杂志

Objective: To understand the performance of 2019-nCoV nucleic acid detection in screening of contacts of COVID-19 cases in same flights and provide evidence for the effective screening of persons at high risk for the infection in domestic flights. Methods: The information of passengers who took same domestic flights with COVID-19 cases in China from April 1, 2020 to April 30, 2022 were retrospectively collected,and χ2 test was used to analyze positive nucleic acid detection rates in the passengers in different times before the onsets of the index cases, in different seat rows and in epidemic periods of different 2019-nCoV variants. Results: During the study period, a total of 433 index cases were identified among 23 548 passengers in 370 flights. Subsequently, 72 positive cases of 2019-nCoV nucleic acid were detected in the passengers, in whom 57 were accompanying persons of the index cases. Further analysis of the another 15 passengers who tested positive for the nucleic acid showed that 86.67% of them had onsets or positive detections within 3 days after the diagnosis of the index cases, and the boarding times were all within 4 days before the onsets of the index cases. The positive detection rate in the passengers who seated in first three rows before and after the index cases was 0.15% (95%CI: 0.08%-0.27%), significantly higher than in the passengers in other rows (0.04%, 95%CI: 0.02%-0.10%, P=0.007),and there was no significant difference in the positive detection rate among the passengers in each of the 3 rows before and after the index cases (P=0.577). No significant differences were found in the positive detection rate in the passengers, except the accompanying persons, among the epidemics caused by different 2019-nCoV variants (P=0.565). During the Omicron epidemic period, all the positive detections in the passengers, except the accompanying persons, were within 3 days before the onset of the index cases. Conclusions: The screening test of 2019-nCoV nucleic acid can be conducted in the passengers took the same flights within 4 days before the onsets of the index cases on board. Passengers who seated within 3 rows from the index cases can considered as the close contacts at high risk for 2019-nCoV, for whom screening should be conducted first and special managements are needed. The passengers in other rows can be classified as general risk persons for screening and management.

Assessment of intensity of seasonal influenza activity in Beijing-Tianjin-Hebei region, 2019-2021 / 中华流行病学杂志

Objective: To explore the feasibility of moving epidemic method (MEM) in the assessment of seasonal influenza (influenza) activity intensity from the perspective of urban agglomeration, assess influenza activity intensity in the Beijing-Tianjin-Hebei region from 2019 to 2021 and evaluate the reliability of surveillance data and the effectiveness of the MEM model application. Methods: The weekly reported incidence rate (IR) of influenza and the percentage of influenza-like illness (ILI%) from 2011-2021 in Beijing-Tianjin-Hebei region were collected to establish MEM models respectively. The model fitting effect and the reliability of the two data were evaluated for the purpose of establishing an optimal model to assess the influenza activity intensity in Beijing-Tianjin-Hebei region from 2019-2021. A cross-validation procedure was used to evaluate the performance of the models by calculating the Youden's index, sensitivity and specificity. Results: The MEM model fitted with weekly ILI% had a higher Youden's index compared with the model fitted with weekly IR at both Beijing-Tianjin-Hebei region level and provincial level. The MEM model based on ILI% showed that the epidemic threshold in Beijing-Tianjin-Hebei region during 2019-2020 was 4.42%, the post-epidemic threshold was 4.66%, with medium, high and very high intensity thresholds as 5.38%, 7.22% and 7.84%, respectively. The influenza season during 2019-2020 had 10 weeks (week 50 of 2019 to week 7 of 2020). The influenza season started in week 50 of 2019, and the intensity fluctuated above and below medium epidemic level for six consecutive weeks. The high intensity was observed in week 4 of 2020, the threshold of very high intensity was excessed in week 5, and the intensity gradually declined and became lower than the threshold at the end of the influenza season in week 8. The epidemic threshold was 4.29% and the post-epidemic threshold was 4.35% during 2020-2021. Influenza activity level never excessed the epidemic threshold throughout the year, and no epidemic period emerged. Conclusions: The MEM model could be applied in the assessment of influenza activity intensity in Beijing-Tianjin-Hebei region, and the use of ILI% to assess influenza activity intensity in this region was more reliable than IR data. Influenza activity intensity in Beijing-Tianjin-Hebei region was higher during 2019-2020 but significantly lower in 2020-2021.

Progress in the practice of surveillance and early warning of infectious diseases in major countries and regions / 中华流行病学杂志

The COVID-19 pandemic is yet another reminder that the threat of infectious disease has never really gone away. As the cornerstone of preventing and controlling infectious diseases, effective surveillance and early warning are of great significance in understanding the outbreak and epidemic of specific infectious diseases and putting forward effective prevention and control measures. Therefore, we must continue strengthening the construction of infectious disease surveillance and early warning system. We reviewed the surveillance and early warning practices of infectious diseases in major countries and regions, then discussed the development direction in the field of surveillance and early warning of infectious diseases to provide the reference for strengthening the construction and capacity of infectious disease surveillance and early warning system in China.

Study on the prevalence of HIV and AIDS-related risky sexual behaviors among male university students who have sex with men in Beijing,China / 中华流行病学杂志

Objective To assess the prevalence of HIV and risky sexual behaviors among university students who have sex with men(MSM)in Beijing.Methods MSM students in the universities were mainly recruited via internet.Questionnaires were self-administered to collect social demographic information and AIDS-related risky sexual behaviors.After completing the questionnaire,blood sample was collected to determine HIV infection through serological testing.X2 test and logistic regression were employed for univariate and multivariate analysis,respectively.Results A total of 157 students were recruited with mean age of 22.7±2.8 years old,12.1%of them were minorities and 77.7% were self-identified as homosexual.98.1% had engaged in anal intercourse(AI)in their lifetime and 73.9%reported that AI was common sexual behavior they often practised.In the past 6 months,58.6% had ever had unprotected anal intercourse(UAI),58.0% never used condoms during oral intercourse,and 59.2% had multiple sex partners(≥2).Nearly half of them believed that they were at low or no risk of contracting HIV and the prevalence of HIV infection was 2.5%.Data from logistic regression analysis showed that ever having had sex with a casual partner in a lifetime (OR=13.10).understanding that serving an insertive role had less risk than being receptive during the AI (OR=3.37),and ever having been to a gay bar(OR=2.49)was independently related to having multiple sex partners in the past 6 months.Conclusion Despite the extensive programs on education,behaviors regarding UAI and ever having had multiple sex partners were silll commonly seen among university MSM students.Interventions were needed to prevent HIV transmission in this population.