A Study of Ad26.COV2.S in Healthy Pregnant Participants (COVID-19) (HORIZON 1)
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The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. |
ClinicalTrials.gov Identifier: NCT04765384 |
Recruitment Status :
Active, not recruiting
First Posted : February 21, 2021
Last Update Posted : May 31, 2023
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Condition or disease | Intervention/treatment | Phase |
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COVID-19 Prevention | Biological: Ad26.COV2.S | Phase 2 |
Expanded Access : An investigational treatment associated with this study is no longer available outside the clinical trial. More info ...
Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 98 participants |
Allocation: | N/A |
Intervention Model: | Single Group Assignment |
Masking: | None (Open Label) |
Primary Purpose: | Prevention |
Official Title: | An Open-label, Phase 2 Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of Ad26.COV2.S in Healthy Pregnant Participants |
Actual Study Start Date : | August 27, 2021 |
Estimated Primary Completion Date : | November 29, 2023 |
Estimated Study Completion Date : | November 30, 2023 |

Arm | Intervention/treatment |
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Experimental: Groups 1-4: Ad26.COV2.S (One Dose)
Participants who are previously vaccinated (Group 1-3) and participants who are vaccine naïve (Group 4) will receive single dose of Ad26.COV2.S vaccine at standard dose level on Day 1. Participants from group 4 who are no longer pregnant may receive single booster dose of Ad26.COV2.S vaccine at standard dose level.
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Biological: Ad26.COV2.S
Participants will receive intramuscular (IM) injection of Ad26.COV2.S.
Other Name: JNJ-78436735, Ad26COVS1 |
- Number of Participants with Solicited Local Adverse Events (AEs) for 7 Days After Vaccination or Until Resolution [ Time Frame: 7 days after vaccination or until resolution (Up to Day 8) ]Solicited local AEs are pre-defined local (at the injection site) AEs for which participants are specifically asked and which are noted by participants in their reactogenicity diary for 7 days post vaccination or until resolution. Solicited local AEs are: injection site pain/tenderness, erythema, swelling at the vaccination site.
- Number of Participants with Solicited Systemic AEs for 7 Days After Vaccination or Until Resolution [ Time Frame: 7 days after vaccination or until resolution (Up to Day 8) ]Participants will be instructed on how to note signs and symptoms in the diary on a daily basis for 7 days post-vaccination (Day of vaccination and the subsequent 7 days) or until resolution for solicited systemic AEs. Solicited systemic events include fatigue, headache, nausea and myalgia.
- Number of Participants with Unsolicited AEs [ Time Frame: 28 days after vaccination (Up to Day 29) ]Unsolicited AEs are all AEs for which the participant is not specifically questioned in the participant's reactogenicity diary.
- Number of Participants with Serious Adverse Events (SAEs) [ Time Frame: Up to 16 months ]SAE is any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important.
- Number of Participants with Adverse Events of Special Interest (AESIs) [ Time Frame: Up to 16 months ]Number of participants with AESIs will be reported. Thrombosis with thrombocytopenia syndrome is considered to be an AESI.
- Number of Participants with Medically-attended Adverse Events (MAAEs) [ Time Frame: 6 months after vaccination (Up to Day 183) ]MAAEs are defined as AEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits will not be considered medically-attended visits. New onset of chronic diseases will be collected as part of the MAAEs.
- Number of Participants with AEs leading to Discontinuation [ Time Frame: Up to 16 months ]An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study.
- Serological Response to Vaccination as Measured by Enzyme-linked Immunosorbent Assay (ELISA) 28 Days After Vaccination [ Time Frame: 28 days after vaccination (Day 29) ]Serological response to vaccination as measured by enzyme-linked immunosorbent assay (S-ELISA, ELISA Units/milliliter [EU/mL]), 28 days after vaccination will be reported.
- Group 4: Number of Adult Participants with Solicited Local AEs for 7 Days After Booster Vaccination or Until Resolution [ Time Frame: Up to 7 days after booster vaccination or until resolution (up to 16 months) ]Solicited local AEs are pre-defined local (at the injection site) AEs for which participants are specifically asked and which are noted by participants in their reactogenicity diary for 7 days post booster vaccination or until resolution. Solicited local AEs are: injection site pain/tenderness, erythema, swelling at the vaccination site.
- Group 4: Number of Adult Participants with Solicited Systemic AEs for 7 Days After Booster Vaccination or Until Resolution [ Time Frame: Up to 7 days after booster vaccination or until resolution (up to 16 months) ]Participants will be instructed on how to note signs and symptoms in the diary on a daily basis for 7 days post-booster vaccination (Day of booster vaccination and the subsequent 7 days) or until resolution for solicited systemic AEs. Solicited systemic events include fatigue, headache, nausea and myalgia.
- Group 4: Number of Adult Participants with Unsolicited AEs For 28 Days After Booster Vaccination [ Time Frame: Up to 28 days after booster vaccination ]Unsolicited AEs are all AEs for which the participant is not specifically questioned in the participant's reactogenicity diary.
- Group 4: Number of Adult Participants with SAEs Throughout the Study (From Booster Vaccination Until End of the Study [EOS]) [ Time Frame: Up to 16 months ]SAE is any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important.
- Group 4: Number of Adult Participants with AESIs Throughout the Study (From Booster Vaccination Until EOS) [ Time Frame: Up to 16 months ]Number of adult participants with AESIs throughout the study (from booster vaccination until EOS) will be reported. Thrombosis with thrombocytopenia syndrome is considered to be an AESI.
- Group 4: Number of Adult Participants with MAAEs Until 6 Months After Booster Vaccination [ Time Frame: 6 months after booster vaccination ]MAAEs are defined as AEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits will not be considered medically-attended visits. New onset of chronic diseases will be collected as part of the MAAEs.
- Number of Adult Participants with AEs leading to Discontinuation (During the Entire Study) [ Time Frame: Up to 16 months ]An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study.
- Number of Adult Participants with Pregnancy Outcomes [ Time Frame: Up to 6 months ]Number of adult participants with pregnancy outcomes (including, live term birth, live preterm birth, stillbirth, and abortion) (non-exhaustive) will be reported.
- Number of Adult Participants with Pregnancy Related AEs [ Time Frame: Up to 6 months ]Number of adult participants with pregnancy-related AEs including: gestational diabetes, gestational hypertension, premature rupture of membranes, premature labor, premature uterine contractions, poor or restricted fetal growth, pre-eclampsia, eclampsia, vaginal or intrauterine hemorrhage (non-exhaustive) will be reported.
- Serological Response to Vaccination as Measured by ELISA and/or Equivalent Assay, at all Blood Collection Timepoints in Adult Participants [ Time Frame: Up to 16 months ]Serological response to vaccination as measured by ELISA (S-ELISA, EU/mL) and/or equivalent assay, at all blood collection timepoints in adult participants will be reported.
- Serological Response to Vaccination as Measured by Virus Neutralization Assay (VNA) Titers, 28 Days After Vaccination in Adult Participants [ Time Frame: 28 days after vaccination (Day 29) ]Serological response to vaccination as measured by VNA titers, 28 days after vaccination in adult participants will be reported.
- Group 4: Serological Response to Booster Vaccination Measured by Binding (S-ELISA and/or Equivalent Assay) in Adult Participants [ Time Frame: Up to 16 months ]Serological response to booster vaccination measured by binding (S-ELISA and/or equivalent assay) in adult participants will be reported.
- Group 4: Serological Response to Booster Vaccination Measured by Neutralizing (VNA) Antibody Titers in Adult Participants [ Time Frame: Up to 16 months ]Serological response to booster vaccination measured by neutralizing (VNA) antibody titers in adult participants will be reported
- Serological Response to Vaccination as Measured by ELISA and/or Equivalent Assay in Infants and Neonates [ Time Frame: From birth up to 2 and 6 months ]Serological response to vaccination as measured by ELISA (S-ELISA, EU/mL) and/or equivalent assay will be reported for neonates and infants (born to adult participants who received vaccination) at birth (in cord blood) and up to 2 months and 6 months of age.
- Serological Response to Vaccination as Measured by VNA Titers at Birth in Neonates and Infants [ Time Frame: At birth ]Serological response to vaccination as measured by VNA titers will be reported for neonates and infants (born to adult participants who received vaccination) at birth (in cord blood).
- Number of Neonates and Infants with SAEs [ Time Frame: From birth up to 12 months ]Number of neonates and infants (born to adult participants who received vaccination) with SAEs including multisystem inflammatory syndrome in children (MIS-C) from birth up to 12 months of age will be reported.
- Number of Neonates and Infants with AESIs [ Time Frame: From birth up to 12 months ]Number of neonates and infants with AESIs will be reported. Thrombosis with thrombocytopenia syndrome is considered to be an AESI.
- Number of Neonates and Infants with MAAEs [ Time Frame: From birth up to 6 months ]Number of neonates and infants (born to adult participants who received vaccination) with MAAEs from birth up to 6 months of age will be reported.
- Number of Neonates and Infants with AEs leading to Study Discontinuation [ Time Frame: From birth up to 12 months ]Number of neonates and infants (born to adult participants who received vaccination) with AEs leading to discontinuation from birth up to 12 months of age will be reported.
- Number of Neonates and Infants with or without any Complications, Anomalies and Deaths [ Time Frame: From birth up to 12 months ]Number of neonates and infants with or without any complication, anomalies and death will be reported. This will also include normal neonate, term neonate with or without complications, preterm neonate with or without complications, neonatal infection, respiratory distress, congenital anomalies, neonatal death, low birth weight, and small for gestational age measured from birth up to 12 months of age (non exhaustive).

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Ages Eligible for Study: | 18 Years to 45 Years (Adult) |
Sexes Eligible for Study: | Female |
Accepts Healthy Volunteers: | Yes |
Inclusion Criteria:
- If on medication for a condition, the medication dose must have been stable for at least 4 weeks preceding vaccination
- Participant must be healthy as confirmed by medical history, physical examination, vital signs, and obstetric history performed at Screening. Participant may have underlying illnesses, as long as the symptoms and signs are medically controlled
- Participant will be at second or third trimester of pregnancy, that is, Week 16 to Week 38 of gestation (inclusive), at the time of vaccination, based on ultrasound at the time of screening (or not longer than 10 days prior to vaccination if performed elsewhere)
- Participant agrees to not donate bone marrow, blood, and blood products from the first study vaccine administration until 3 months after receiving the last dose of study vaccine
- Participant must be willing to provide verifiable identification, has means to be contacted and to contact the investigator during the study
- Participant either received their last COVID-19 vaccination with an authorized/licensed COVID-19 vaccine (at least 4 months prior to first study vaccination) or is COVID 19 vaccine-naïve
Exclusion Criteria:
- Participants with medical or obstetric histories that put them at higher risk for maternal or fetal complications (example, chronic pregnancy-related disorders, birth defects or genetic conditions during previous pregnancy)
- Participant with abnormal pregnancy screening test (example, ultrasound fetal abnormalities, maternal blood screen)
- Participant has a history of malignancy within 2 years before screening (exceptions are squamous, basal cell carcinomas of the skin, carcinoma in situ of the cervix, or malignancy, considered cured with minimal risk of recurrence)
- Participant has a known or suspected allergy or history of anaphylaxis or other serious adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine)
- Participant has a history of any serious, chronic, or progressive neurological disorders or seizures including Guillain-Barre syndrome, with the exception of febrile seizures during childhood
- Participant has a positive diagnostic test result (polymerase chain reaction [PCR] based viral ribonucleic acid [RNA] detection) severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection at screening or Day 1 (if more than 4 days in between)
- Participant has a history of thrombosis with thrombocytopenia syndrome (TTS), including cerebral venous sinus thrombosis (CVST), or heparin-induced thrombocytopenia (HIT)
- Participant has a history of capillary leak syndrome (CLS)

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04765384

Study Director: | Janssen Vaccines & Prevention B.V. Clinical Trial | Janssen Vaccines & Prevention B.V. |
Responsible Party: | Janssen Vaccines & Prevention B.V. |
ClinicalTrials.gov Identifier: | NCT04765384 |
Other Study ID Numbers: |
CR108962 2020-005330-14 ( EudraCT Number ) VAC31518COV2004 ( Other Identifier: Janssen Vaccines & Prevention B.V. ) |
First Posted: | February 21, 2021 Key Record Dates |
Last Update Posted: | May 31, 2023 |
Last Verified: | May 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Yes |
Plan Description: | The data sharing policy of the Janssen Pharmaceutical Companies of Johnson & Johnson is available at www.janssen.com/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu |
URL: | https://www.janssen.com/clinical-trials/transparency |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
COVID-19 Pneumonia, Viral Pneumonia Respiratory Tract Infections Infections Virus Diseases |
Coronavirus Infections Coronaviridae Infections Nidovirales Infections RNA Virus Infections Lung Diseases Respiratory Tract Diseases |