HUMAN VACCINES & IMMUNOTHERAPEUTICS 2016, VOL. 12, NO. 11, 2749–2752 http://dx.doi.org/10.1080/21645515.2016.1208327
RESEARCH PAPER
Coverage estimates and patterns of inactivated poliovirus vaccine (IPV) use prior to and during the polio eradication endgame, Jinan City, China, 2010–2015 Caiyun Chang, Ji Zhang, Jingwen Zhou, Ruoming Cao, Kaijun Song, Chong Liu, Xianhui Zhang, Xingyi Geng, Xiaoxue Liu, and Chuanbin Li Jinan Center for Disease Control and Prevention, Jinan, Shandong, China
ABSTRACT
ARTICLE HISTORY
Background: Use of inactivated poliovirus vaccine (IPV) in Jinan during the polio eradication endgame has not been previously documented. Two IPV-containing vaccines were made available as an option for Jinan parents in 2009. We describe coverage levels and patterns of use of IPV over time using data from the Jinan Childhood Immunization Information Management System (JNCIIMS). Methods: Children born between January 2010 and December 2014 who were registered in JNCIIMS were included in this study. Vaccination records were obtained from JNCIIMS on April 30, 2015. JNCIIMS distinguishes among available poliovirus vaccines; doses administered data were used to describe IPV usage over time. We identified the polio vaccination sequences used by children in the 2012 and 2013 birth cohorts. Coverage estimates were analyzed by birth cohort and migration status. We developed 3 categories for analysis: “resident child,” “migrant child” and “other child” according to migration status. Results: In total, 12,354 (11.7%) IPV, 5,893(5.6%) DTP-IPV-Hib vaccine and 87,054(82.7%) OPV doses were administered to children in the 2010 to 2014 birth cohorts. The proportion of children using an IPV-only schedule increased each year, consistent with the introduction of IPV that is called for by the Polio Eradication Endgame Strategic Plan 2013–2018. During this time, 4.7% children used a schedule containing both IPV and oral poliovirus vaccine (OPV). In the 2012 to 2013 birth cohorts, 14.4% children used an IPV-only schedule; 5.7% children used a sequential schedule, and 79.9% used OPV-only schedule. Use of IPV only schedules was higher among migrant children than among resident children. Among those sequential schedule using both IPV and OPV, 87.2% children used IPV for the first dose and 12.8% used OPV for the first dose. Conclusions: JNCIIMS provided a mechanism for tracking IPV and OPV vaccination patterns, and showed areas in need of improvement. Ensuring appropriately sequenced IPV and OPV supports reduction of risk of vaccine associated paralytic polio.
Received 28 March 2016 Revised 20 June 2016 Accepted 25 June 2016
Introduction In 2012, the Global Polio Eradication Initiative partners developed the Polio Eradication and Endgame Strategic Plan 2013– 2018, which was subsequently approved by the World Health Assembly.1 This plan includes the introduction of at least one dose of inactivate polio vaccine (IPV) into routine immunization schedules as a strategy to reduce risk from type 2 vaccinederived polioviruses (VDPV2) following the withdrawal of Sabin type 2 strains from oral polio vaccine (OPV).2 IPV provides a base of immunity that can be boosted with monovalent OPV2 in case of a VDPV2 outbreak. IPV induces long lasting immunity and does not cause vaccine-associated paralytic poliomyelitis (VAPP) or VDPVs. In 2009, imported IPV-containing vaccines were licensed and made available in China as private-sector, parent-pay vaccines.3 IPV became available in Jinan in April of 2009. Although IPV was made available in China, utilization was low due to its high price. In contrast, OPV has always been provided at no charge to parents, regardless of socioeconomic status. Huizhou City in Guangdong Province introduced IPV into
CONTACT Ji Zhang © 2016 Taylor & Francis
[email protected]
KEYWORDS
coverage rate; Inactivate polio vaccine; sequential schedule
the management of the Expanded Program on Immunization making the vaccine available at no charge. However, in other cities IPV remained an option for parents to consider, although they would have to pay for the vaccine. Optional use of IPV has not been documented. We used data from the Jinan Childhood Immunization Information Management System (JNCIIMS) to describe polio vaccination coverage and patterns of use of IPV and OPV in order to provide baseline data and experience to inform national immunization strategies.
Results In total, 105,301 doses of polio vaccine were administered to children in the 2010 to 2014 birth cohorts; 87,054 (82.7%) doses were OPV, 12,354 (11.7%) were IPV, and 5,893(5.6%) were DTP-IPV-Hib combined vaccine. Table 1 shows vaccine use by year. Table 2 shows use of different polio vaccination schedules by year of birth. Use of IPV-only schedules increased over time, but they were used less frequently than an OPV-only schedule and more frequently than sequential schedules.
2 Weiliu Road, Huaiyin District, Jinan, Shandong, China.
2750
C. CHANG ET AL.
Table 1. Different types of polio vaccine used by year of birth. Type OPV IPV DTP-IPV-Hib combined vaccine Total
2010
2011
2012
2013
2014
Total
16,760 375 19
18,712 830 53
16,967 1,966 866
16,127 3,693 1,765
18,488 5,490 3,190
87,054 12,354 5,893
17,154
19,595
19,799
21,585
27,168
10,5301
population. A weakness is that JNCIIMS may underestimate coverage due to incomplete provider reporting. Children not captured by JNCIIMS may differ in their immunization status from children in JNCIIMS, but this should have minimal impact on coverage rates, as over 95% of children are registered in Jinan CIIMS. An advantage of our study is that we were able to determine trends in utilization of IPV-containing vaccines going into the early part of the Polio Eradication Endgame Strategic Plan 2013–2018. This information may help to predict IPV demand after the globally-synchronized switch from trivalent OPV to bivalent OPV and nationwide introduction of IPV. Like other immunization information systems, the JNCIIMS platform is able to provide data to assess immunization coverage levels. In the United States, Shauer and colleagues estimated baseline childhood immunization rates using an immunization information system.5 Zhang and colleagues6 assessed the status of CIIMS in Shandong province, and they found that the CIIMS was in universal use in Jinan by the end of 2012. We found that polio vaccination coverage for migrant children was lower than for resident children in both 2012 and 2013 birth cohorts, which is consistent with previous research in China.7 Our study has program implications. The risk of VAPP is highest with the first dose of OPV in an all-OPV schedule. The rate of VAPP associated with the first dose of OPV has been shown to be approximately 1 case per 0.9 million doses, a 6.6fold greater risk than that following exposure to subsequent doses of OPV.8 The introduction of inactivated poliovirus vaccines with enhanced potency9 has generated interest in sequential schedules with IPV given before OPV to reduce risk of VAPP.10 Our study showed that among children using a sequential schedule, 87.2% used IPV for first dose for 2012 and 2013 birth cohort; however, 12.8% child used a sequential schedule that started with OPV, which provide less protection from VAPP than an IPV-first schedule. Our findings support 2 recommendations. First, it is important to increase the basic immunization coverage rate of polio vaccine, especially among migrant children. Second, ensuring appropriately sequenced IPV and OPV supports reduction of risk of vaccine associated paralytic polio.
To ensure that children were old enough to have received at least 3 polio vaccine doses by April 30, 2015, we conducted analyses restricted to the 2012 and 2013 cohorts. Table 3 shows use of different schedules by birth cohort and by migration status for children in the 2012 and 2013 cohorts. Use of IPV only schedules was higher among migrant children than among resident children. Table 4 shows use of sequential schedules by the type of polio vaccine used for the first dose – IPV or OPV. For the 2012 and 2013 birth cohorts, 87.2% children used an IPV-first sequential schedule, with a higher percentage in the 2013 birth cohort; 77.2% of migrant children used an IPV-first sequential schedule, compared with 89.2% of resident children. Table 5 shows variants of sequential schedules for the 2012 and 2013 birth cohort children. Among children in these cohorts, 55.8% used an IPV-IPV-OPV sequential schedule, 28.8% used an IPV-OPV-OPV sequential schedule.
Discussion Our study took advantage of the Jinan Childhood Immunization Information Management System (CIIMS) to evaluate coverage and use of IPV in Jinan in the years prior to the nationwide introduction of IPV into China. Use of IPV-containing schedules increased from less than 3% the year after IPV became available in Jinan to approximately 30% 4 y later. Use of an all-OPV schedule decreased concomitantly. We also showed that vaccination coverage levels for migrant children were lower than for resident children in the 2012 and 2013 birth cohorts. In these cohorts, 12.8% of children used an OPV-IPV sequential schedule, which provides less protection from VAPP than an IPV-first schedule. A strength of our study is that it used JNCIIMS, which serves as the official vaccination record for children in Jinan. Because it is the official record, JNCIIMS is the most accurate method to evaluate and establish baseline coverage.4,5 A second advantage of JNCIIMS is that it is considered as a census of all children
RESEARCH PAPER
Coverage estimates and patterns of inactivated poliovirus vaccine (IPV) use prior to and during the polio eradication endgame, Jinan City, China, 2010–2015 Caiyun Chang, Ji Zhang, Jingwen Zhou, Ruoming Cao, Kaijun Song, Chong Liu, Xianhui Zhang, Xingyi Geng, Xiaoxue Liu, and Chuanbin Li Jinan Center for Disease Control and Prevention, Jinan, Shandong, China
ABSTRACT
ARTICLE HISTORY
Background: Use of inactivated poliovirus vaccine (IPV) in Jinan during the polio eradication endgame has not been previously documented. Two IPV-containing vaccines were made available as an option for Jinan parents in 2009. We describe coverage levels and patterns of use of IPV over time using data from the Jinan Childhood Immunization Information Management System (JNCIIMS). Methods: Children born between January 2010 and December 2014 who were registered in JNCIIMS were included in this study. Vaccination records were obtained from JNCIIMS on April 30, 2015. JNCIIMS distinguishes among available poliovirus vaccines; doses administered data were used to describe IPV usage over time. We identified the polio vaccination sequences used by children in the 2012 and 2013 birth cohorts. Coverage estimates were analyzed by birth cohort and migration status. We developed 3 categories for analysis: “resident child,” “migrant child” and “other child” according to migration status. Results: In total, 12,354 (11.7%) IPV, 5,893(5.6%) DTP-IPV-Hib vaccine and 87,054(82.7%) OPV doses were administered to children in the 2010 to 2014 birth cohorts. The proportion of children using an IPV-only schedule increased each year, consistent with the introduction of IPV that is called for by the Polio Eradication Endgame Strategic Plan 2013–2018. During this time, 4.7% children used a schedule containing both IPV and oral poliovirus vaccine (OPV). In the 2012 to 2013 birth cohorts, 14.4% children used an IPV-only schedule; 5.7% children used a sequential schedule, and 79.9% used OPV-only schedule. Use of IPV only schedules was higher among migrant children than among resident children. Among those sequential schedule using both IPV and OPV, 87.2% children used IPV for the first dose and 12.8% used OPV for the first dose. Conclusions: JNCIIMS provided a mechanism for tracking IPV and OPV vaccination patterns, and showed areas in need of improvement. Ensuring appropriately sequenced IPV and OPV supports reduction of risk of vaccine associated paralytic polio.
Received 28 March 2016 Revised 20 June 2016 Accepted 25 June 2016
Introduction In 2012, the Global Polio Eradication Initiative partners developed the Polio Eradication and Endgame Strategic Plan 2013– 2018, which was subsequently approved by the World Health Assembly.1 This plan includes the introduction of at least one dose of inactivate polio vaccine (IPV) into routine immunization schedules as a strategy to reduce risk from type 2 vaccinederived polioviruses (VDPV2) following the withdrawal of Sabin type 2 strains from oral polio vaccine (OPV).2 IPV provides a base of immunity that can be boosted with monovalent OPV2 in case of a VDPV2 outbreak. IPV induces long lasting immunity and does not cause vaccine-associated paralytic poliomyelitis (VAPP) or VDPVs. In 2009, imported IPV-containing vaccines were licensed and made available in China as private-sector, parent-pay vaccines.3 IPV became available in Jinan in April of 2009. Although IPV was made available in China, utilization was low due to its high price. In contrast, OPV has always been provided at no charge to parents, regardless of socioeconomic status. Huizhou City in Guangdong Province introduced IPV into
CONTACT Ji Zhang © 2016 Taylor & Francis
[email protected]
KEYWORDS
coverage rate; Inactivate polio vaccine; sequential schedule
the management of the Expanded Program on Immunization making the vaccine available at no charge. However, in other cities IPV remained an option for parents to consider, although they would have to pay for the vaccine. Optional use of IPV has not been documented. We used data from the Jinan Childhood Immunization Information Management System (JNCIIMS) to describe polio vaccination coverage and patterns of use of IPV and OPV in order to provide baseline data and experience to inform national immunization strategies.
Results In total, 105,301 doses of polio vaccine were administered to children in the 2010 to 2014 birth cohorts; 87,054 (82.7%) doses were OPV, 12,354 (11.7%) were IPV, and 5,893(5.6%) were DTP-IPV-Hib combined vaccine. Table 1 shows vaccine use by year. Table 2 shows use of different polio vaccination schedules by year of birth. Use of IPV-only schedules increased over time, but they were used less frequently than an OPV-only schedule and more frequently than sequential schedules.
2 Weiliu Road, Huaiyin District, Jinan, Shandong, China.
2750
C. CHANG ET AL.
Table 1. Different types of polio vaccine used by year of birth. Type OPV IPV DTP-IPV-Hib combined vaccine Total
2010
2011
2012
2013
2014
Total
16,760 375 19
18,712 830 53
16,967 1,966 866
16,127 3,693 1,765
18,488 5,490 3,190
87,054 12,354 5,893
17,154
19,595
19,799
21,585
27,168
10,5301
population. A weakness is that JNCIIMS may underestimate coverage due to incomplete provider reporting. Children not captured by JNCIIMS may differ in their immunization status from children in JNCIIMS, but this should have minimal impact on coverage rates, as over 95% of children are registered in Jinan CIIMS. An advantage of our study is that we were able to determine trends in utilization of IPV-containing vaccines going into the early part of the Polio Eradication Endgame Strategic Plan 2013–2018. This information may help to predict IPV demand after the globally-synchronized switch from trivalent OPV to bivalent OPV and nationwide introduction of IPV. Like other immunization information systems, the JNCIIMS platform is able to provide data to assess immunization coverage levels. In the United States, Shauer and colleagues estimated baseline childhood immunization rates using an immunization information system.5 Zhang and colleagues6 assessed the status of CIIMS in Shandong province, and they found that the CIIMS was in universal use in Jinan by the end of 2012. We found that polio vaccination coverage for migrant children was lower than for resident children in both 2012 and 2013 birth cohorts, which is consistent with previous research in China.7 Our study has program implications. The risk of VAPP is highest with the first dose of OPV in an all-OPV schedule. The rate of VAPP associated with the first dose of OPV has been shown to be approximately 1 case per 0.9 million doses, a 6.6fold greater risk than that following exposure to subsequent doses of OPV.8 The introduction of inactivated poliovirus vaccines with enhanced potency9 has generated interest in sequential schedules with IPV given before OPV to reduce risk of VAPP.10 Our study showed that among children using a sequential schedule, 87.2% used IPV for first dose for 2012 and 2013 birth cohort; however, 12.8% child used a sequential schedule that started with OPV, which provide less protection from VAPP than an IPV-first schedule. Our findings support 2 recommendations. First, it is important to increase the basic immunization coverage rate of polio vaccine, especially among migrant children. Second, ensuring appropriately sequenced IPV and OPV supports reduction of risk of vaccine associated paralytic polio.
To ensure that children were old enough to have received at least 3 polio vaccine doses by April 30, 2015, we conducted analyses restricted to the 2012 and 2013 cohorts. Table 3 shows use of different schedules by birth cohort and by migration status for children in the 2012 and 2013 cohorts. Use of IPV only schedules was higher among migrant children than among resident children. Table 4 shows use of sequential schedules by the type of polio vaccine used for the first dose – IPV or OPV. For the 2012 and 2013 birth cohorts, 87.2% children used an IPV-first sequential schedule, with a higher percentage in the 2013 birth cohort; 77.2% of migrant children used an IPV-first sequential schedule, compared with 89.2% of resident children. Table 5 shows variants of sequential schedules for the 2012 and 2013 birth cohort children. Among children in these cohorts, 55.8% used an IPV-IPV-OPV sequential schedule, 28.8% used an IPV-OPV-OPV sequential schedule.
Discussion Our study took advantage of the Jinan Childhood Immunization Information Management System (CIIMS) to evaluate coverage and use of IPV in Jinan in the years prior to the nationwide introduction of IPV into China. Use of IPV-containing schedules increased from less than 3% the year after IPV became available in Jinan to approximately 30% 4 y later. Use of an all-OPV schedule decreased concomitantly. We also showed that vaccination coverage levels for migrant children were lower than for resident children in the 2012 and 2013 birth cohorts. In these cohorts, 12.8% of children used an OPV-IPV sequential schedule, which provides less protection from VAPP than an IPV-first schedule. A strength of our study is that it used JNCIIMS, which serves as the official vaccination record for children in Jinan. Because it is the official record, JNCIIMS is the most accurate method to evaluate and establish baseline coverage.4,5 A second advantage of JNCIIMS is that it is considered as a census of all children
