A study to see if a new 6-in-1 (hexavalent) vaccine is effective and safe for babies in countries with polio
| ISRCTN | ISRCTN16504454 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN16504454 |
| Protocol serial number | 10032025 |
| Sponsor | Aga Khan University Hospital |
| Funder | World Health Organization |
- Submission date
- 26/11/2025
- Registration date
- 13/01/2026
- Last edited
- 26/01/2026
- Recruitment status
- Not yet recruiting
- Overall study status
- Ongoing
- Condition category
- Infections and Infestations
Plain English summary of protocol
Background and study aims
Polio is still present in Pakistan, and children are vaccinated using two types of polio vaccines: OPV (oral polio vaccine) and IPV (injected polio vaccine). Currently, babies receive several separate injections for different diseases. A new vaccine called Hexavalent (Hexasiil) combines protection against six illnesses—diphtheria, tetanus, whooping cough, hepatitis B, Hib, and polio—into one shot. This study will check if the Hexavalent vaccine works as well as the current schedule of Pentavalent (five-in-one) plus IPV for protecting against polio. Researchers will also look at whether giving four doses of Hexavalent makes a difference.
Who can participate?
Healthy babies who were born full-term (at least 37 weeks), are 6–8 weeks old when joining the study, live in the study area for at least 3 months, and have parents or guardians who agree to take part. Babies cannot join if they are very ill, severely underweight, have immune problems, certain medical conditions, or allergies to vaccine ingredients.
What does the study involve?
Babies will be randomly placed into one of four groups. Each group gets a different vaccination schedule using either the Hexavalent vaccine or the current Pentavalent plus IPV schedule. Vaccines will be given at either 6, 10, and 14 weeks or at 2, 4, and 6 months. Parents will bring their baby for blood tests at the start and at several points until the baby is 9 months old. These tests check how well the vaccines worked. After each vaccination, babies will be observed for 30 minutes and parents will record any side effects for 28 days.
What are the possible benefits and risks of participating?
Benefits include babies receiving WHO-approved vaccines under close medical care, parents learning more about vaccination and follow-up care, and the study helping improve Pakistan’s immunization program. Risks include common side effects like pain, swelling, redness, or fever, and rare but serious allergic reactions. If any serious problems occur, the study team will act quickly and may stop further vaccinations. Safety is monitored by an independent committee.
Where is the study run from?
The study is led by the Clinical Trial Unit at Aga Khan University Hospital in Karachi, Pakistan. Recruitment happens in Cattle Colony, Ibrahim Hyderi, and Aga Khan Hospital for Women and Children in Kharadar.
When is the study starting and how long is it expected to run for?
The study will run for about 24 months. This includes time for approvals, training, recruitment, vaccinations, follow-up, and analysis. The exact start date depends on ethics approval.
Who is funding the study?
Funding is requested from the WHO Global Polio Eradication Initiative (GPEI) – Polio Research Committee.
Who is the main contact?
Dr Ali Faisal Saleem
Department of Paediatrics and Child Health
Aga Khan University, Karachi, Pakistan
ali.saleem@aku.edu
Contact information
Principal investigator
Deaprtment of Peadiatrics and Child Health, Aga Khan University Hospital, Stadium Road
Karachi
74800
Pakistan
 ORCID ID |
0000-0003-1804-9868 |
|---|---|
| Phone | +92 3002245776 |
| ali.saleem@aku.edu |
Scientific
Department of Peadiatrics and Child Health, Aga Khan University Hospital, Stadium Road
Karachi
74800
Pakistan
| ORCID ID |
0000-0003-3669-0851 |
|---|---|
| Phone | +92 3008250671 |
| zaubina.kazi@aku.edu |
Public
Department of Peadiatrics and Child Health, Aga Khan University Hospital, Stadium Road
Karachi
74800
Pakistan
| ORCID ID |
0000-0001-9446-3468 |
|---|---|
| Phone | +92 3332232023 |
| mahjabeen.zehra@aku.edu |
Study information
| Primary study design | Interventional |
|---|---|
| Study design | Open label- randomized controlled trial |
| Secondary study design | Randomised controlled trial |
| Scientific title | Randomized trial to evaluate and compare the immunogenicity and safety of hexavalent vaccine in healthy infants in a polio-endemic country |
| Study objectives | Primary objectives: 1. To compare the humoral immunity against type 1-3 poliovirus after administering 3 doses of the Hexavalent schedule (Arm A) and compare it with the national EPI schedule of pentavalent + IPV administered at 6, 10, and 14 weeks of age (Arm B) 2. To compare the humoral immunity against type 1-3 poliovirus after administering 3 doses of the Hexavalent schedule (Arm C) and compare it with routine immunization pentavalent + IPV administered at 2, 4, and 6 months of age (Arm D) 3. To compare the humoral immunity against type 1-3 poliovirus after administering 4 doses of the Hexavalent schedule given according to the national EPI schedule at 6, 10, 14 weeks, and 9 months of age (Group I) with Hexavalent doses given at 2, 4, 6, and 12 months of age (Group II) Secondary objectives: 1. To evaluate the humoral immunity against type 1-3 poliovirus after administering the Hexavalent vaccine schedule at 6, 10, and 14 weeks (Arm A) and 2, 4, and 6-month schedule (Arm C) |
| Ethics approval(s) |
Approved 27/03/2025, Aga Khan University Ethical Review Committee (Stadium Road, P. O. Box 3500, Karachi, 74800, Pakistan; +92 21 3493 0051 Ext: 2447/4988; erc.pakistan@aku.edu), ref: 2025-10964-33978 |
| Health condition(s) or problem(s) studied | Polio virus |
| Intervention | This is a randomized, open-label, controlled clinical trial designed to evaluate and compare the immunogenicity and safety of a newly prequalified hexavalent vaccine (Hexasiil®, Serum Institute of India) with the currently used pentavalent plus inactivated polio vaccine (IPV) under Pakistan’s national immunization schedule. Healthy full-term infants aged 6–8 weeks will be enrolled from peri-urban communities of Karachi and the Aga Khan Hospital for Women and Children, Kharadar. A total of 1,760 infants will be randomized equally into four parallel arms using stratified blocked randomization. Infants starting at six weeks (Group I) will receive either Hexavalent + OPV or Pentavalent + OPV + IPV according to the national EPI schedule, while those starting at two months (Group II) will receive the same vaccines at 2, 4 and 6 months. The hexavalent vaccine (0.5 mL intramuscularly) contains diphtheria, tetanus, whole-cell pertussis, hepatitis B, Haemophilus influenzae type b, and inactivated poliovirus types 1–3. The comparator pentavalent vaccine contains DTP, Hep B and Hib, administered with separate IPV doses. Blood samples will be collected at baseline and 28 days after each vaccination for antibody assessment. Safety will be monitored through active follow-up, 30-minute post-vaccination observation, and diary-based adverse-event reporting. An independent Data Safety Monitoring Board will oversee participant safety throughout the study. |
| Intervention type | Drug |
| Phase | Not Applicable |
| Drug / device / biological / vaccine name(s) | Hexasiil |
| Primary outcome measure(s) |
The proportion of infants achieving seroprotection against poliovirus types 1, 2, and 3, measured using blood samples will be for antibody assessment at 4 weeks after the third dose |
| Key secondary outcome measure(s) |
The proportion of infants achieving seroprotection against poliovirus types 1, 2, and 3, measured 4 using blood samples will be for antibody assessment at weeks after the third dose of the Hexavalent vaccine |
| Completion date | 01/01/2027 |
Eligibility
| Participant type(s) | Healthy volunteer |
|---|---|
| Age group | Child |
| Lower age limit | 6 Weeks |
| Upper age limit | 8 Weeks |
| Sex | All |
| Target sample size at registration | 1760 |
| Key inclusion criteria | 1. All healthy full-term infants (born at 37 weeks) at 6-8 weeks old of either gender 2. Not planning to travel away during entire the study period (enrolment- approximately 294 days; 5 weeks – 42 weeks) 3. Parents resident of the study area for the last 3 months at the time of enrolment 4. Parent/guardian provides informed consent |
| Key exclusion criteria | 1. Newborns found acutely ill at the time of enrolment and requiring emergent medical care/hospitalization. 2. Enrolment weight & height <-3 weight for height z-score 3. Infants with certain medical conditions i.e., syndromic infants, infants with petechial, purpura, or bleeding disorder (contraindication of intramuscular injections) 4. A diagnosis or suspicion of immunodeficiency disorder (either in the participant or in a member of the immediate family - e.g. several early infant deaths, a household member on chemotherapy) will render the newborn ineligible for the study 5. Diagnosed neurological disorder or a history of seizures or temperature >380C in last 3 days or any other indication of acute illness/infection within the past 7 days 6. Having a record of anaphylaxis or allergy to vaccine components |
| Date of first enrolment | 01/03/2026 |
| Date of final enrolment | 01/09/2026 |
Locations
Countries of recruitment
- Pakistan
Study participating centre
Stadium Road, P. O. Box 3500
Karachi
74800
Pakistan
Results and Publications
| Individual participant data (IPD) Intention to share | Yes |
|---|---|
| IPD sharing plan summary | Available on request |
| IPD sharing plan | The datasets generated during and/or analysed during the current study wil lbe available upon request from Ali Faisal Saleem ali.saleem@aku.edu |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Protocol file | version 1.0 | 14/12/2024 | 01/12/2025 | No | No |
Additional files
- 48565 Protocol v1.0 14Dec2024.pdf
- Protocol file
Editorial Notes
26/01/2026: The date of first enrolment was changed from 01/01/2026 to 01/03/2026.
26/11/2025: Trial's existence confirmed by Aga Khan University.
