[Surveillance and response to measles outbreaks in China, 2016-2020]

Objective: To understand the epidemiological characteristics of measles outbreaks in China from 2016 to 2020 and related outbreak investigations and response performances. Methods: The information about the incidence of measles outbreaks, the investigation and response of measles outbreaks in 31 provinces from 2016 to 2020 were collected from Measles Surveillance System, and the incidence of suspected measles outbreaks detected through sporadic case finding during the same period according to the measles outbreak definition was analyzed. Results: From 2016 to 2020, a total of 344 measles outbreaks were reported nationwide, involving 1 886 measles cases. The median of intervals between the first case onsets and reported outbreaks ranged from 4 to 10 days, the median of the numbers of involved cases ranged from 2 to 3, and the median of the duration of the epidemic ranged from 8 to 13 days, and some outbreaks had long durations of 65,44,28,63 and 13 days. The top three provinces with high number of reported outbreaks were Gansu, Beijing and Shandong. Among the reported outbreaks, 115 occurred in communities/villages, accounting for the highest proportion. The genotype identification results indicated that all the outbreaks in 2016 were caused by measles virus H1, and the proportion of the outbreaks caused by measles virus H1 decreased year by year since then, which was 88.57% (31/35) in 2017, 85.00% (17/20) in 2018 and 15.79% (3/19) in 2019 respectively. There was no outbreak caused by measles H1 reported in 2020, the 4 isolates all belonged to genotype D8. Active case findings were conducted in local medical institutions for 313 outbreaks, and measles-containing vaccine coverage surveys were conducted for 266 outbreaks. From 2016 to 2020, a total of 919 suspected measles outbreaks were detected nationwide, involving 4 212 measles cases. The top three provinces with suspected measles outbreaks were Xinjiang, Gansu and Sichuan. The suspected measles outbreaks also mainly occurred in communities/villages (493). Conclusions: The number, scale and duration of measles outbreaks were gradually decreasing, the measles outbreaks at the community level can not be ignored, and the local H1 genotypes tend to be gradually replaced by other genotypes. Improving the sensitivity of outbreak surveillance, promoting vaccination, expanding the vaccine coverage, timely and effective response to the outbreaks are the focus of measles elimination in China in the future.

[Associations of Dairy Consumption during Pregnancy and Neonatal Birth Body Mass: a Prospective Study]

Objective

To investigate the dairy product intake during pregnancy in Southwest China and to explore its relationship with neonatal birth body mass.

Methods

A prospective study was conducted to select healthy singleton pregnant women at 8-14 weeks of gestation in a maternal and fetal health care institution in Chengdu City. Dairy product consumption during the first, second, third trimester of pregnancy were collected by 24-hour dietary recalls at 8-14 weeks, 24-28 weeks and 32-36 weeks of pregnancy, respectively, and the total milk intake and milk consumption rate were calculated. According to the dietary guidelines for Chinese pregnant women (2016), the recommended amount of milk (300 g/d) was used as the standard to calculate the compliance rate. The respondents were divided into three groups: no dairy consumption group, insufficient dairy consumption group and suitable dairy consumption group. The gestational age at delivery and neonatal birth body mass were collected by the hospital information system. Logistic regression model was used to analyze the association between milk intake during pregnancy and neonatal birth body mass.

Results

A total of 962 pregnant women were included. The average milk intake in the first, second and third trimester of pregnancy were 125.0 (0, 236.1) g/d, 208.3 (0, 284.7) g/d and 250.0 (150.0, 416.7) g/d, respectively, with the compliance rates of 12.6%, 33.2% and 48.4%, respectively. The average neonatal birth body mass was (3 225.0±399.8) g. The incidence of small for gestational age (SGA) and large for gestational age (LGA) was 8.3% and 3.9%, respectively. Compared with no dairy consumption group in the second trimester of pregnancy, the risk of SGA was lower in suitable dairy consumption group (odds ratio (OR)=0.786, 95% confidence interval (CI): 0.385-0.976). Compared with no dairy consumption group in the third trimester of pregnancy, the risk of SGA was lower in insufficient dairy consumption group and suitable dairy consumption group (OR=0.672, 95%CI: 0.477-0.821 and OR=0.497, 95%CI: 0.116-0.807, respectively). No association was observed between milk intake in the first trimester and neonatal birth body mass, and milk intake in the second and third trimester of pregnancy was not associated with the risk of LGA.

Conclusion

Insufficient milk intake of pregnant women is a significant problem in southwest China and needs to be improved. Milk intake during pregnancy is associated with neonatal birth body mass, and increased milk intake in the second and third trimester of pregnancy may reduce the risk of SGA.

Vaccine-derived poliovirus surveillance in China during 2001-2013: the potential challenge for maintaining polio free status

Background

The goal of polio eradication is to complete elimination and containment of all wild, vaccine-related and Sabin polioviruses. Vaccine-derived poliovirus (VDPV) surveillance in China from 2001–2013 is summarized in this report, which has important implications for the global polio eradication initiative.

Methods

Acute flaccid paralysis (AFP) cases and their contacts with VDPVs isolated from fecal specimens were identified in our AFP surveillance system or by field investigation. Epidemiological and laboratory information for these children were analyzed and the reasons for the VDPV outbreak was explored.

Results

VDPVs were isolated from a total of 49 children in more than two-thirds of Chinese provinces from 2001–2013, including 15 VDPV cases, 15 non-polio AFP cases and 19 contacts of AFP cases or healthy subjects. A total of 3 circulating VDPVs (cVDPVs) outbreaks were reported in China, resulting in 6 cVDPVs cases who had not been vaccinated with oral attenuated poliomyelitis vaccine. Among the 4 immunodeficiency-associated VDPVs (iVDPVs) cases, the longest duration of virus excretion was about 20 months. In addition, one imported VDPV case from Myanmar was detected in Yunnan Province.

Conclusions

Until all wild, vaccine-related and Sabin polioviruses are eradicated in the world, high quality routine immunization and sensitive AFP surveillance should be maintained, focusing efforts on underserved populations in high risk areas.

[Epidemic profile of mumps in China during 2004-2013]

OBJECTIVE

To analyze the epidemiological characteristics of mumps in China from 2004 to 2013.

METHODS

Data of mump cases occurring between 2004 and 2013 were gathered from the national notifiable disease reporting system in China (excluding Hong Kong, Macao, and Taiwan); only cases classified as "final card" , laboratory confirmed, or clinical diagnosis were included. Descriptive epidemiology techniques were used to analyze features of sex, age, trends over time, and geography.

RESULTS

Average incidence of mumps between 2004 to 2013 was 24.20/100 000. Peaks were in 2011 and 2012, with incidence 33.9/100 000 (454 385/1.340 million) and 35.6/100 000 (479 518/1.347 million). Two seasonal peaks occurred regularly in years, one from April to July in the first year, and the other from November to January in the next year. During the study period, provinces with the highest incidence were Ningxia, Tibet, Xinjiang, and Guangxi; incidences were 72.1/100 000 (4 425/6.13 million), 48.5/100 000 (1 396/3 million), 51.7/100 000 (10 887/21.04 million), and 40.8/100 000 (19 179/46.99 million), respectively. Guangdong (28 078), Sichuan (21 924), Guangxi (21 616), and Zhejiang (20 000) provinces reported the highest number of mumps cases. Beijing, Tianjin, and Shanghai showed a consistently low incidence. Mumps cases occurred primarily among children aged 5-9 years, with incidence ranging from 118.2/100 000 to 281.4/100 000. In 2004-2008, the peak age was 6-8 years (174.1/100 000) and in 2009-2013, peak age was 5-7 years (234.5/100 000).

CONCLUSION

The highest incidences of mumps in China were reported in 2011 and 2012, with children of school age constituting the majority of cases.

[Spatial autocorrelation analysis of measles in China, 2005-2014]

OBJECTIVE

To detect the spatial features of measles in China by means of spatial statistical analysis.

METHODS

Data of prefecture-level measles cases and incidence from 2005 to 2014 were collected from the China Information System for Disease Control and Prevention. Information collected from the system included demographic characteristics, spatial distribution information, and diagnostic reports. Cases of unconfirmed measles and those with unknown address were ruled out. Cases from Hong Kong, Macao, Taiwan, and foreign countries were not included in this study. Maps were obtained from geographical boundary data at prefecture level from the Chinese Center for Disease Control and Prevention and demographic data from the National Bureau of Statistics. Based on different measures of measles elimination, we divided the data from 2005 to 2014 into three stages: stage 1 (2005-2008), stage 2 (2009-2012), and stage 3 (2013-2014). ArcGIS software was used to describe the spatial distribution and for global and local spatial autocorrelation analysis.

RESULTS

The total number of confirmed measles cases reported in the system was 650 222, with average incidence 0.46/100 000. The highest reported incidence was in 2008 (9.95/100 000) and the lowest in 2012 (0.46/100 000). Average incidences for stages 1, 2, and 3 were 8.87/100 000, 1.99/100 000 and 2.96/100 000, respectively. Global Moran's I coefficients from 2005 to 2014 were 0.31, 0.08, 0.36, 0.56, 0.26, 0.48, 0.34, 0.20, 0.29 and 0.52, respectively; all were significant (P<0.05). Average incidences for high-high (H-H) clusters in 2005-2008, 2009-2012, and 2013-2014 were 33.02/100 000, 7.06/100 000, 11.91/100 000, respectively. Western China had high-value clustering consistently throughout all three periods; however, the number of prefectures covered by high-value clusters and discrepancy in the incidence between western and eastern regions were low. Northeast and northern China had H-H clustering in stages 2 and 3.

CONCLUSION

In this study, measles incidence was spatially autocorrelated at the prefecture level from 2005 to 2014. Although China has made great progress in the elimination of measles, H-H clusters were consistently present. A need remains in China for targeted measles prevention and control measures.

An outbreak of type π vaccine-derived poliovirus in Sichuan province, China: emergence and circulation in an under-immunized population

BACKGROUND

During August 2011-February 2012, an outbreak of type Π circulating vaccine-derived poliovirus (cVDPVs) occurred in Sichuan Province, China.

METHODS

A field investigation of the outbreak was conducted to characterize outbreak isolates and to guide emergency response. Sequence analysis of poliovirus capsid protein VP1 was performed to determine the viral propagation, and a coverage survey was carried out for risk assessment.

RESULTS

One clinical compatible polio case and three VDPV cases were determined in Ngawa County, Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan Province. Case patients were unimmunized children, 0.8-1 years old. Genetic sequencing showed that the isolates diverged from the VP1 region of the type Π Sabin strain by 5-12 nucleotides (nt) and shared the same 5 nt VP1 substitutions, which indicate single lineage of cVDPVs. Of the 7 acute flaccid paralysis cases (all>6 months) reported in Ngawa Prefecture in 2011, 4 (57.1%) cases (including 2 polio cases) did not receive oral attenuated poliovirus vaccine. Supplementary immunization activities (SIAs) were conducted in February-May, 2012, and the strain has not been isolated since.

CONCLUSION

High coverage of routine immunization should be maintained among children until WPV transmission is globally eradicated. Risk assessments should be conducted regularly to pinpoint high risk areas or subpopulations, with SIAs developed if necessary.

Enhanced surveillance of acute flaccid paralysis following importation of wild poliovirus in Xinjiang Uygur Autonomous Region, China

Background

After being polio free for more than 10 years, an outbreak occurred in China in 2011 in Xinjiang Uygur Autonomous Region (Xinjiang) following the importation of wild poliovirus (WPV) originating from neighboring Pakistan.

Methods

To strengthen acute flaccid paralysis (AFP) surveillance in Xinjiang, “zero case daily reporting” and retrospective searching of AFP cases were initiated after the confirmation of the WPV outbreak. To pinpoint all the polio cases in time, AFP surveillance system was expanded to include persons of all ages in the entire population in Xinjiang.

Results

Totally, 578 AFP cases were reported in 2011 in Xinjiang, including 21 WPV cases, 23 clinical compatible polio cases and 534 non-polio AFP cases. Of the 44 polio cases, 27 (61.4%) cases were reported among adults aged 15–53 years. Strengthening AFP surveillance resulted in an increase in the number of non-polio AFP cases in 2011 (148 children < 15 years) compared with 76 cases < 15 years in 2010. The AFP surveillance system in Xinjiang was sensitive enough to detect polio cases, with the AFP incidence of 3.28/100,000 among children < 15 years of age.

Conclusions

Incorporating adult cases into the AFP surveillance system is of potential value to understand the overall characteristics of the epidemic and to guide emergency responses, especially in countries facing WPV outbreak following long-term polio free status. The AFP surveillance system in Xinjiang was satisfactory despite limitations in biological sample collection.

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.

[Progress on rubella control and immunization strategies]

Rubella is one of the global public health problems, and the main harm is CRS which derives from pregnant women that infected rubella virus in the first pregnant periods. CRS could cause great economic burden to society. In order to decrease the incidence of Rubella and CRS, China has integrated MMR into Expanded Program on Immunization (EPI) in 2007. This article will provide some ideas on Rubella vaccine into EPI. The paper will review the rubella vaccine immunigation Strategy both at home and abroad.