Cross-sectional Study to Assess Persistence of Immunity Conferred by a Single IPV Dose Administered in the Expanded Program on Immunization(EPI) Routine Immunization Schedule
试验速览
- 阶段
- 4 期
- 状态
- 已完成
- 发起方
- 入组人数
- 502
- 试验地点
- 3
- 主要终点
- Proportion of children with detectable immunity against type 2 poliovirus
研究概览
简要总结
In 2015, Strategic Advisory Group of Experts in Immunization (SAGE) recommended the global switch from trivalent to bivalent oral poliovirus vaccine (OPV) that does not contain type 2 poliovirus and introduction of a single dose of inactivated poliovirus vaccine (IPV) to maintain population immunity to type 2 polio to reduce the risk of vaccine derived polio. Following SAGE recommendations, Nepal introduced one dose of IPV in routine immunization in 2015 followed by withdrawal trivalent OPV in April 2016. However, Nepal, like many other countries had to stop vaccination by the end of 2016 because of a global shortage of IPV.
Single dose of IPV induces detectable antibodies in 34% to 80% of infants, compared to >90% after three doses and most of seronegative children (84-98%) are "immunologically primed" by the first dose. Primed individuals produce protective antibody levels in serum within one week of exposure to a new dose of IPV or OPV. However, it is unknown whether seroconversion or priming responses persist, and for how long they persist after the single dose of IPV. IPV immunogenicity for vaccine delivered low-resource countries may also be inferior to that observed in clinical trials because of program factors that decrease vaccine efficacy.
This cross sectional study aims to determine whether the immune response provided by a single dose of IPV delivered through routine immunization services persists for more than a year.
The study will be implemented in three study sites in Kathmandu, Nepal during November 2018- July 2019.
Information generated from this study is expected to allow better estimation of children partially protected (primed) or fully protected against type 2 poliovirus depending on coverage and time since last IPV vaccination. These estimates will help inform the Global Polio Eradication Initiative (GPEI) on vaccine choices for responding to type 2 vaccine derived poliovirus (VDPV) outbreaks and will help guide decisions on polio immunization schedules for Nepal and for other countries in future.
详细描述
Background and Rationale
Importance of Poliomyelitis and Polioviruses and vaccine
There are three polioviruses types, 1, 2 and 3, with minimal cross-immunity. About 1/200 infections (depending on the type of poliovirus) produce paralytic poliomyelitis. An estimated 5-10% of individuals with paralytic poliomyelitis die and the remaining suffer from lifelong paralysis of one or more limbs without a cure. The presence of detectable antibodies in blood against each type protects against paralytic poliomyelitis, but intestinal immunity develops only after exposure to live poliovirus (vaccine or wild). Oral poliovirus vaccines that contain attenuated poliovirus strains and inactivated poliovirus vaccine both induce humoral immunity and protect against paralysis. OPV can also immunize or boost immunity of close contacts through secondary spread and trivalent OPV (tOPV) with poliovirus types 1, 2 and 3, was the vaccine of choice for polio eradication.
The immunological response to poliovirus vaccines is evaluated by measuring type-specific poliovirus antibodies using neutralization assays and can be detected as early as 1 to 3 days after infection with WPV or receipt of OPV or IPV. Antibody titers usually decline in the first two years (10- to 100-fold reduction) and then plateau, persisting for many years. However, administration of additional doses of vaccine or new exposures to wild poliovirus, induces a quick rise in antibody titers, with a peak reached within one week after the dose due to induction of "priming" or immunological memory.
Changes in polio vaccine use with progress in global polio eradication
研究设计
- 研究类型
- Interventional
- 分配方式
- Non Randomized
- 干预模型
- Parallel
- 主要目的
- Prevention
- 盲法
- None
入排标准
- 年龄范围
- 7 Months 至 36 Months（Child）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •We will be including Nepali infants who fulfil the following criteria:
- •Born after 30 April 2016
- •Healthy infant or mild illness
- •Age groups within one of the following age groups: 7-12 months or >24 months.
- •Receipt of one dose of IPV at 3- 6 months of age (if age >24months) or zero doses (if age within 7-12 months). IPV receipt must be validated through immunization card or registry book.
- •Parents that consent for participation in the full length of the study.
- •Parents those are able to understand and comply with planned study procedures.
排除标准
- •Parents and infants who are unable to participate in the full length of the study.
- •A diagnosis or suspicion of immunodeficiency disorder either in the infant or in an immediate family member.
- •A diagnosis or suspicion of bleeding disorder that would contraindicate parenteral administration of IPV or collection of blood by venipuncture.
- •Acute infection or illness at the time of enrollment that would require infant's admission to a hospital.
- •Evidence of a chronic medical condition identified by a study medical officer during physical exam.
- •Known allergy/sensitivity or reaction to polio vaccines.
- •Discontinuation Criteria
- •Withdrawal of consent for participation for any reason.
- •Request by parents of participant to terminate all study procedures.
- •Identification of immunodeficiency disorder, bleeding disorder or another medical condition for which continued participation, in the opinion of the principal investigator, would pose a risk to the participant to continue in the study.
- •Receipt of immunosuppressive medications.
- •Receipt of any polio (OPV or IPV) vaccine outside of study after enrollment (as per parent's report).
- •Allergic reaction to a dose of polio vaccine.
- •Unable to collect or obtain blood at enrollment.
- •Premature termination of the study.
- •Temporary discontinuation of study activities may occur if there is a mOPV2 campaign.
研究组 & 干预措施
Study Arm A
Children {Age > 24 months and who received a single dose Inactivated Polio Vaccine (IPV) at the time of routine immunization} in this arm will receive an IPV (0.5ml) intramuscularly at the time of enrolment in the trial
干预措施: Inactivated Polio Vaccine (IPV) (Biological)
Study arm B
Children {Age 7-12 months and have not received any IPV till date of enrolment} in this arm will receive an Inactivated Polio Vaccine, IPV (0.5 ml) intramuscularly at the time of enrolment in the trial and a repeat dose of IPV (0.5 ml) after 1 month
干预措施: Inactivated Polio Vaccine (IPV) (Biological)
结局指标
主要结局
Proportion of children with detectable immunity against type 2 poliovirus
时间窗: 5 weeks
To compare the proportion of infants vaccinated with one dose of IPV after 14 weeks of age who are seropositive or primed against type 2 poliovirus, either \> 21 months after vaccination (study group), or one month after vaccination (control group)
次要结局
- Proportion of children who seroconvert or boost antibody titers to type 2 poliovirus(5 weeks)
研究者
Arun Kumar Sharma
Co PI, Associate Professor, Department of Pediatrics
Tribhuvan University Teaching Hospital, Institute Of Medicine.