An interventional study of Serological study after yellow fever vaccination in Yellow Fever, sponsored by Ministry of Public Health, Argentina. Active, not recruiting at 3 sites in Argentina. Open to participants aged 4 Years to 8 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2024-12-09.
Sponsored by Ministry of Public Health, Argentina · Not applicable, Interventional, and Prevention
Northern Argentina is a risk area for yellow fever (YF). Recent studies have suggested that immunity wanes in children vaccinated between 9 and 23 months of age. In 2015, a collaborative study conducted by the Ministry of Health (MoH) of Argentina, the Pan American Health Organization (PAHO), and the US Centers for Disease Control and Prevention (CDC) assessed the immunogenicity and safety of co-administration of YF and MMR vaccines in a pediatric population at 12-13 months of age. A total of 741 children presenting for routine immunization at 12-13 months of age enrolled and completed the study. It is now four to seven years since this pediatric group received their YF vaccinations. This cohort is unique because their initial YF vaccination and immune response to the vaccine dose are well characterized. Contact information collected during the earlier study will be used to locate the children. If consent is obtained, a 5ml specimen of blood will be collected and shipped to the CDC's Arboviral Diseases Reference Laboratory (ADRL) in Fort Collins, CO for plaque reduction neutralization testing using a 50% cut-off (PRNT50) to detect YF virus-specific neutralizing antibodies. Children with neutralizing antibody titers that are higher than their baseline titer collected approximately 28 days following YF vaccination will have PRNTs done for cross-reacting flaviviruses.
Yellow fever (YF) continues to be a public health problem for 13 countries in the Americas, including northern Argentina. From 1960 to 2019, these countries reported 9,673 confirmed cases and 2,480 deaths. In the same period, Argentina reported 69 confirmed cases with two deaths. Vaccination against YF is recommended for all children living in risk areas in the Americas. In Argentina, the vaccine was administered at the same visit as the measles, mumps, and rubella (MMR) vaccine at 12 months of age.
A study published in 2011 found that simultaneous vaccination with YF and MMR vaccines had a negative impact on YF, mumps, and rubella seroconversion rates in Brazilian children aged 12 to 23 months. In 2013, the Strategic Advisory Group of Experts (SAGE) on immunization reviewed the available data on the co-administration of the YF vaccine with other inactivated and lived attenuated vaccines. In its June 2013 position paper, the WHO states that the YF vaccine can be co-administered with other vaccines but recommends further studies on co-administration with other vaccines, including MMR. In 2013, the Ministry of Health of Argentina changed the indication age for the YF vaccine to be administered to the pediatric population of 18 months, given concerns about a possible interference with MMR and the number of additional vaccines recommended for the pediatric population of 12 months.
In 2015, a collaborative study between the Ministry of Health (MoH) of Argentina, the Pan American Health Organization (PAHO), and the US Centers for Disease Control and Prevention (CDC) was initiated to assess the immunogenicity and the safety of joint administration of the YF and MMR vaccines in the pediatric population vaccinated at 12-13 months of age. 741 children presenting for routine immunization at 12-13 months of age enrolled and completed the study. Three randomized groups received the YF and MMR vaccines simultaneously or 28 days apart. The study found high seroconversion rates against all antigens in the co-administered and sequential groups. However, the magnitude of the antibody response was lower for YF, rubella, and mumps when the vaccines were co-administered.
The WHO currently states that a single dose of the YF vaccine is sufficient to confer lifelong sustained protective immunity against the disease; a booster dose is unnecessary. However, since the booster dose requirement was removed in 2013, new data have been published from pediatric population cohorts in Brazil, Mali, and Ghana, indicating a decrease in the proportion of children seropositive for neutralizing antibodies over time. Seropositivity rates as low as 28% for children in Ghana have been reported two years after vaccination. Given these findings, WHO and PAHO have prioritized obtaining additional longer-term immunogenicity data for the pediatric population vaccinated against YF.
The children who participated in the Argentina YF and MMR vaccination study provide an opportunity to assess whether the Argentine childhood immunization program provides adequate long-term immunity against YF. The last minor enrolled in 2018; It has been four to seven years since this pediatric group received their regular YF vaccinations. This cohort is unique because their initial YF vaccination and immune response to the vaccine dose are well characterized. This program evaluation is necessary to provide Argentina with evidence to inform future changes to its childhood immunization schedule.
Contact information collected during the co-administration study will be used to locate the children who completed the study. If consent is obtained, a 5ml specimen of blood will be collected and shipped to the CDC's Arboviral Diseases Reference Laboratory (ADRL) in Fort Collins, CO for plaque reduction neutralization testing using a 50% cut-off (PRNT50) to detect YF virus-specific neutralizing antibodies. Children with neutralizing antibody titers that are higher than their baseline titer collected approximately 28 days following YF vaccination will have PRNTs done for cross-reacting flaviviruses.
52 studies on the registry are indexed under Yellow Fever; 10 are open to participants now.
This study's enrollment of 361 is above the median of 112 across 43 interventional studies indexed under Yellow Fever.
Browse Yellow Fever studies →Ministry of Public Health, Argentina is the lead sponsor of 5 studies on the registry; none are open to participants now.
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Exclusion Criteria:
Children in the 2015 study received one dose of the Yellow Fever vaccine and had NO documented seroconversion.
Weakened immune function, including infection, primary immunodeficiencies, having received immunosuppressive doses of oral or injectable (or equivalent), having received immunomodulators or chemotherapeutic agents, disease of the thymus, Severe illness/fever (mild illness without fever is not an exclusion criteria)
● Any condition that, in the judgment of study personnel, poses a risk to the health of the participant or interferes with the assessment of response to the vaccine
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Yellow fever seropositive pediatric population in Argentina after receiving the YF vaccine at 12-23 months of age.
Biological: Serological study after yellow fever vaccination
It is a serological survey of the cohort of children who participated in the preliminary investigation and seroconverted after vaccination against yellow fever.
Also known as: Immunogenicity after yellow fever vaccine
The proportion of the pediatric population seropositive for yellow fever ≥ 4 years after yellow fever vaccination at 12-23 months of age in Argentina.
The proportion of children with detectable neutralizing antibodies 4-7 years following yellow fever vaccination.
Time frame: 4-7 years following vaccination
To assess the influence of simultaneous administration versus sequential administration 28 days apart of yellow fever and MMR vaccines on yellow fever seropositivity and neutralizing antibody titers four to seven years later.
In the co-administration study, the target population was randomized into three groups. Group 1 received the yellow fever and MMR vaccines simultaneously, group 2 received the MMR vaccine followed by the yellow fever vaccine 28 days later, and group 3 received the yellow fever vaccine followed by the MMR vaccine 28 days later.
Time frame: 4-7 years following vaccination
Plan to share: Yes — Deidentified datasets generated in this study, including particular individual data that underlie the results reported in this article after identification, will be available for three years, starting after publication, to researchers who provide a methodologically sound proposal. All variables deemed to be personally identifiable information will be categorized or removed. The study protocol and informed consent forms will be available also.
Supporting information: Study protocol, Informed consent form
Time frame: It will be available for three years, starting after publication.
Access criteria: Data will be available to researchers who provide a methodologically sound proposal. All variables deemed to be personally identifiable information will be categorized or removed. The information will be available from the lead contact upon request.
Ran from Dec 2022 to primary completion in Sep 2023, 9 months.
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This study is active, not recruiting, as verified in Dec 2024. You cannot join it, but the record below documents what was studied.
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Ministry of Public Health, Argentina