Abstract In April 2021, type Ⅰ vaccine-derived poliovirus (VDPV) was detected from two fecal samples of a male infant with acute flaccid paralysis (AFP) in Zhejiang Province when he was admitted to the Children's Hospital Affiliated to Fudan University in Shanghai, with 12 and 14 nucleotide mutations in the VP1 region, respectively. The case had a history of immunization with three doses of poliovirus vaccines, and grade Ⅲ proximal muscle strength and grade Ⅱ distal muscle strength of the right lower limb. After symptomatic treatment, the activity of the right lower limb and the muscle strength was significantly restored, thus he was discharged. VDPV was not detected from subsequent (the 8th to 12th) fecal samples of the case and fecal samples of close contacts. No similar cases were found in medical institutions in the county, surrounding areas, neighboring villages or towns. Since the case did not exhibit clinical symptoms of poliomyelitis caused by VDPV, poliomyelitis was excluded, and the case was diagnosed with hemophilia type A based on the epidemiological investigation, laboratory tests, and the history of poliomyelitis vaccination. This event involved cross-provincial (municipal) cooperation and was responsed promptly, preventing further spread of the virus. It suggested that the sensitivity of the AFP case surveillance system should be maintained, environmental monitoring methods should be increased, and the poliomyelitis vaccination should be promoted to prevent the spread of the virus.

OBJECTIVES: Several countries have successfully eliminated measles, and China is making significant strides toward achieving this goal. This study focused on investigating the patterns of measles infections in Zhejiang Province, China, as well as control measures. The objective was to provide valuable insights that could contribute to the development of nationwide elimination strategies. METHODS: We analyzed measles surveillance data from 2005 to 2022 in Zhejiang Province. We utilized a joinpoint regression model to examine trends in measles. Additionally, we employed SaTScan version 9.5 to identify spatial-temporal clusters. Finally, we used an age-period-cohort model to assess the effects of age, period, and cohort. RESULTS: The age-standardized incidence rate (ASIR) of measles infection in Zhejiang Province from 2005 to 2022 was 5.24 per 100,000, showing a consistent and significant downward trend with an annual percentage change of -24.93% (p<0.05). After 2020, the ASIR for measles infection fell to below 0.1 per 100,000. The majority of measles cases occurred in individuals either without an immunization history or with an unknown immunization status, representing 41.06% and 41.40% of the cases from 2010 to 2022, respectively. According to data from the National Measles Surveillance System, the annual rate of discarded measles cases from 2009 to 2014, and the annual rate of discarded measles and rubella cases from 2015 to 2022, were both above 2 per 100,000, indicating the high sensitivity of the measles surveillance system. CONCLUSIONS The significant reduction in measles incidence from 2005 to 2022 demonstrates substantial progress in Zhejiang Province towards the elimination of measles.

OBJECTIVES: Several countries have successfully eliminated measles, and China is making significant strides toward achieving this goal. This study focused on investigating the patterns of measles infections in Zhejiang Province, China, as well as control measures. The objective was to provide valuable insights that could contribute to the development of nationwide elimination strategies. METHODS: We analyzed measles surveillance data from 2005 to 2022 in Zhejiang Province. We utilized a joinpoint regression model to examine trends in measles. Additionally, we employed SaTScan version 9.5 to identify spatial-temporal clusters. Finally, we used an age-period-cohort model to assess the effects of age, period, and cohort. RESULTS: The age-standardized incidence rate (ASIR) of measles infection in Zhejiang Province from 2005 to 2022 was 5.24 per 100,000, showing a consistent and significant downward trend with an annual percentage change of -24.93% (p<0.05). After 2020, the ASIR for measles infection fell to below 0.1 per 100,000. The majority of measles cases occurred in individuals either without an immunization history or with an unknown immunization status, representing 41.06% and 41.40% of the cases from 2010 to 2022, respectively. According to data from the National Measles Surveillance System, the annual rate of discarded measles cases from 2009 to 2014, and the annual rate of discarded measles and rubella cases from 2015 to 2022, were both above 2 per 100,000, indicating the high sensitivity of the measles surveillance system. CONCLUSIONS The significant reduction in measles incidence from 2005 to 2022 demonstrates substantial progress in Zhejiang Province towards the elimination of measles.

OBJECTIVES: Several countries have successfully eliminated measles, and China is making significant strides toward achieving this goal. This study focused on investigating the patterns of measles infections in Zhejiang Province, China, as well as control measures. The objective was to provide valuable insights that could contribute to the development of nationwide elimination strategies. METHODS: We analyzed measles surveillance data from 2005 to 2022 in Zhejiang Province. We utilized a joinpoint regression model to examine trends in measles. Additionally, we employed SaTScan version 9.5 to identify spatial-temporal clusters. Finally, we used an age-period-cohort model to assess the effects of age, period, and cohort. RESULTS: The age-standardized incidence rate (ASIR) of measles infection in Zhejiang Province from 2005 to 2022 was 5.24 per 100,000, showing a consistent and significant downward trend with an annual percentage change of -24.93% (p<0.05). After 2020, the ASIR for measles infection fell to below 0.1 per 100,000. The majority of measles cases occurred in individuals either without an immunization history or with an unknown immunization status, representing 41.06% and 41.40% of the cases from 2010 to 2022, respectively. According to data from the National Measles Surveillance System, the annual rate of discarded measles cases from 2009 to 2014, and the annual rate of discarded measles and rubella cases from 2015 to 2022, were both above 2 per 100,000, indicating the high sensitivity of the measles surveillance system. CONCLUSIONS The significant reduction in measles incidence from 2005 to 2022 demonstrates substantial progress in Zhejiang Province towards the elimination of measles.

Objective: To analyze the strengths, weaknesses, opportunities and threats of the construction on intelligent vaccination clinics in Zhejiang Province, so as to provide countermeasures for promoting the construction of intelligent vaccination clinics in Zhejiang Province. Methods: By reviewing the annual reports of Zhejiang immunization planning, survey data from Zhejiang Centers for Disease Control and Prevention and Immunization Intelligent Service System, data of human resources of immunization planning, vaccine procurement, construction progress of intelligent vaccination clinics and vaccination were collected. The relevant literature was searched to gather information on the construction standards and norms of intelligent vaccination clinics. The analysis of the strengths, weaknesses, opportunities and threats (SWOT) of the construction of intelligent vaccination clinics was conducted, and corresponding countermeasures and suggestions were proposed. Results: The National Immunization Program reported vaccine rate in Zhejiang Province is more than 99%, and standardized vaccination clinics have been popularized throughout the province. The vaccination staff are professional, and a province-wide intelligent immunization service information system has been established, providing the resources and conditions for the construction of intelligent vaccination clinics. However, there are problems such as low data quality and matching efficiency in vaccination, insufficient data interoperability and sharing, unbalanced regional capabilities in intelligent transformation, and uneven distribution of talent and resources. It is crucial to seize the opportunities presented by the development of big data and artificial intelligence, rely on the regional development of the Internet and health industry, seize the opportunity of rapid growth in demand for intelligent vaccination services and high public acceptance, accelerate the construction of intelligent vaccination clinics, and establish intelligent vaccination service standards as soon as possible. Conclusion We should seize the opportunities presented by the digital reform and development, fully utilize the existing vaccination resources and strengths, address the shortcomings, and accelerate the construction of intelligent vaccination clinics in Zhejiang Province.

Objective:To evaluate the epidemiological characteristics and explore the associated factors of breakthrough cases (BC) from Public Health Emergency Events (PHEEs) of varicella in Zhejiang Province from 2019 to 2022.Methods:Data on cases were obtained from the China Information System for Disease Control and Prevention and the PHEEs Reporting Information Database of Varicella in Zhejiang Province. History records were matched through the Zhejiang Provincial Immunization Information System. Descriptive analysis and multiple logistic regression model with a bidirectional stepwise selection method were performed to explore associated factors for BC during 2019-2022.Results:A total of 144 276 varicella cases were reported from 2019 to 2022, with the annual reported incidence of 47.35-82.80 cases per 100 000 population. Among these cases, 109 172 were non-breakthrough cases (NBC, accounting for 75.67%), 34 517 were BC (23.92%), and the rest 587 cases had unclear vaccination history on varicella (0.41%). A total of 214 PHEEs of varicella were reported, of which 99.07% occurred in school settings. The proportion of PHEEs that occurred in high school increased significantly as time went on ( χ2trend=5.742, P=0.017). Multiple logistic regression model which focused on "BC vs. NBC (as the reference)" indicated that the year of onset ( OR=1.585, 95% CI:1.343-1.878), the month of onset (taking January as the reference, OR=2.311-15.652), city (taking Hangzhou as the reference, Jiaxing OR=2.370, Jinhua OR=2.197, Lishui OR=0.134), age ( OR=0.887, 95% CI: 0.826-0.944), PHEEs setting (taking "primary school and below" as the reference, "high school and above" OR=0.516, 95% CI: 0.305-0.897), and the number of rashes ( OR=0.569, 95% CI: 0.458-0.703) were associated factors. Multiple logistic regression model which focused on "two-dose BC vs. one-dose BC (as the reference)" showed that the age of initial vaccination ( OR=0.045, 95% CI: 0.014-0.107), the time interval from onset to the last dose ( OR=0.037, 95% CI: 0.011-0.087) and the age of onset ( OR=20.724, 95% CI: 8.383-72.485) were associated factors. Conclusion:During 2019-2022, the reported high-risk group of varicella in Zhejiang Province has shifted to adolescents and young adults. Although vaccination could not completely prevent the onset of VZV, it could relieve clinical symptoms and delay the age of onset.

Objective:To evaluate the epidemiological characteristics and explore the associated factors of breakthrough cases (BC) from Public Health Emergency Events (PHEEs) of varicella in Zhejiang Province from 2019 to 2022.Methods:Data on cases were obtained from the China Information System for Disease Control and Prevention and the PHEEs Reporting Information Database of Varicella in Zhejiang Province. History records were matched through the Zhejiang Provincial Immunization Information System. Descriptive analysis and multiple logistic regression model with a bidirectional stepwise selection method were performed to explore associated factors for BC during 2019-2022.Results:A total of 144 276 varicella cases were reported from 2019 to 2022, with the annual reported incidence of 47.35-82.80 cases per 100 000 population. Among these cases, 109 172 were non-breakthrough cases (NBC, accounting for 75.67%), 34 517 were BC (23.92%), and the rest 587 cases had unclear vaccination history on varicella (0.41%). A total of 214 PHEEs of varicella were reported, of which 99.07% occurred in school settings. The proportion of PHEEs that occurred in high school increased significantly as time went on ( χ2trend=5.742, P=0.017). Multiple logistic regression model which focused on "BC vs. NBC (as the reference)" indicated that the year of onset ( OR=1.585, 95% CI:1.343-1.878), the month of onset (taking January as the reference, OR=2.311-15.652), city (taking Hangzhou as the reference, Jiaxing OR=2.370, Jinhua OR=2.197, Lishui OR=0.134), age ( OR=0.887, 95% CI: 0.826-0.944), PHEEs setting (taking "primary school and below" as the reference, "high school and above" OR=0.516, 95% CI: 0.305-0.897), and the number of rashes ( OR=0.569, 95% CI: 0.458-0.703) were associated factors. Multiple logistic regression model which focused on "two-dose BC vs. one-dose BC (as the reference)" showed that the age of initial vaccination ( OR=0.045, 95% CI: 0.014-0.107), the time interval from onset to the last dose ( OR=0.037, 95% CI: 0.011-0.087) and the age of onset ( OR=20.724, 95% CI: 8.383-72.485) were associated factors. Conclusion:During 2019-2022, the reported high-risk group of varicella in Zhejiang Province has shifted to adolescents and young adults. Although vaccination could not completely prevent the onset of VZV, it could relieve clinical symptoms and delay the age of onset.

OBJECTIVES: Several countries have successfully eliminated measles, and China is making significant strides toward achieving this goal. This study focused on investigating the patterns of measles infections in Zhejiang Province, China, as well as control measures. The objective was to provide valuable insights that could contribute to the development of nationwide elimination strategies. METHODS: We analyzed measles surveillance data from 2005 to 2022 in Zhejiang Province. We utilized a joinpoint regression model to examine trends in measles. Additionally, we employed SaTScan version 9.5 to identify spatial-temporal clusters. Finally, we used an age-period-cohort model to assess the effects of age, period, and cohort. RESULTS: The age-standardized incidence rate (ASIR) of measles infection in Zhejiang Province from 2005 to 2022 was 5.24 per 100,000, showing a consistent and significant downward trend with an annual percentage change of -24.93% (p<0.05). After 2020, the ASIR for measles infection fell to below 0.1 per 100,000. The majority of measles cases occurred in individuals either without an immunization history or with an unknown immunization status, representing 41.06% and 41.40% of the cases from 2010 to 2022, respectively. According to data from the National Measles Surveillance System, the annual rate of discarded measles cases from 2009 to 2014, and the annual rate of discarded measles and rubella cases from 2015 to 2022, were both above 2 per 100,000, indicating the high sensitivity of the measles surveillance system. CONCLUSIONS The significant reduction in measles incidence from 2005 to 2022 demonstrates substantial progress in Zhejiang Province towards the elimination of measles.

Abstract Vaccine-hypervariable poliovirus type Ⅲ was detected in an acute flaccid paralysis infant at age of 6 months in Zhejiang Province in June, 2021, and the isolated and incubated virus had six nucleotide variations in the VP1 region as compared to the poliovirus Sabin vaccine strain. The infant had a history of three-dose poliovirus vaccination, and grade 2 muscle strength of the left upper limb upon onset. He was clinically diagnosed with cellulitis of the left shoulder, and recovered to normal following treatment. No abnormality was detected in the nervous system, and the infant was cured and discharged from hospital. No vaccine-hypervariable poliovirus was detected in subsequent infant' clinical samples or in close contacts, and no similar cases were identified during the active case detection by county/district medical institutions and among community populations. Since the infant did not present poliomyelitis-related clinical symptoms caused by vaccine-hypervariable poliovirus, poliomyelitis was excluded. The vaccine-hypervariable poliovirus was not spread because of timely identification and effective responses, suggesting the urgent need to maintain the sensitivity of the acute flaccid paralysis surveillance system and improve the coverage of poliovirus vaccination, so as to inhibit the transmission of poliovirus.

Objective: To investigate the serum levels of anti-measles antibody among residents in Zhejiang Province in 2018, so as to provide insights into measles control. Methods: Permanent residents aged 0 to 59 years were recruited using the stratified multistage random sampling method in Zhejiang Province in 2018, and subjects' demographic features, medical history of measles and history of immunization with measles-containing vaccine (MCV) were collected using a questionnaire survey. The serum level of anti-measles IgG antibody was detected, and the geometric mean concentration (GMC) of anti-measles IgG antibody was estimated. The seroprevalence, protective rate and GMC of anti-measles IgG antibody were compared among residents at different age groups and regions. Results: A total of 4 189 residents were enrolled, including 1 939 males and 2 250 females, with a male to female ratio of 1∶1.16. There were 3 858 residents positive for anti-measles IgG antibody, with seroprevalence of 92.10%, and there were 2 072 residents with protective antibodies against measles, with a protective rate of 49.46%. The median GMC of anti-measles IgG antibody was 798.33 (interquartile range, 1 024.06) mIU/mL, and the protective rate of anti-measles IgG antibody appeared a tendency towards a decline with age ( χ2trend=18.067, P<0.001 ). There were significant differences in the seroprevalence ( χ2=45.090, P<0.001 ), protective rate ( χ2=57.432, P<0.001 ) and GMC of anti-measles IgG antibody (χ2=88.624, P<0.001 ) among residents at different regions, with the lowest seroprevalence of anti-measles IgG antibody in Ningbo City ( 85.19% ), the lowest antibody-protective rate (38.98%) and the lowest GMC [632.89 ( 909.04 ) mIU/mL] in Zhoushan City, the highest seroprevalence ( 95.16% ), antibody-protective rate (58.48%) and GMC [1 035.84 ( 1 301.77 ) mIU/mL] in Huzhou City. Conclusions The protective rate of anti-measles antibody was low and appeared a tendency towards a decline among residents in Zhejiang Province in 2018. There was a region-specific serum level of anti-measles antibody in Zhejiang Province in 2018.