Clinical Trials For Vaccines in India: Step-by-Step Guide

Vaccine clinical trials in India follow a highly structured and regulated pathway to ensure safety and effectiveness before public use. The clinical trial for vaccines in India begins with research and preclinical studies, followed by Phase I–III human trials to evaluate safety, dosage, and immune response. After a stringent review by CDSCO in compliance with the New Drugs and Clinical Trials Rules (NDCT) rules 2019, vaccines are approved for sale in the market. Even after approval, ongoing surveillance ensures long-term safety, effectiveness, and detection of rare adverse effects in the population.

Clinical Trials for Vaccines in India

Vaccines are biological products that help protect from infectious diseases by stimulating the body’s immune response. They may contain weakened or inactivated microorganisms, toxins, or surface proteins that help the immune system recognize and fight harmful pathogens. In India, vaccine regulation is overseen by the Central Drugs Standard Control Organization (CDSCO), under the Drug Controller General of India (DCGI), to ensure vaccine safety, quality, and effectiveness.

Before approval, vaccines must pass through several stages, including exploratory research, preclinical studies, clinical trials for vaccine phases (Phase I to Phase III), regulatory review, and post-marketing surveillance. In India, this entire pathway is strictly governed by the Drugs and Cosmetics Act of 1940. Each stage helps evaluate whether the vaccine is safe and effective for public use.

Step 1: Exploratory Research and Vaccine Discovery

The vaccine development process begins with exploratory research and vaccine discovery. In this stage, scientists identify a suitable antigen that may help protect against a particular disease. The following activities are carried out during this stage:

Researchers study weakened viruses or bacteria, virus-like particles, or other substances obtained from pathogens.
This stage mainly involves laboratory-based research and scientific evaluation.
Scientists analyze whether the vaccine candidate can produce an immune response.

This stage may take several years because it involves extensive research, approvals, and funding requirements.2

Step 2: Preclinical Testing of Vaccine Clinical Trials in India

The preclinical stage evaluates the safety, immune response, and possible effectiveness of the vaccine in vitro before human testing begins in vaccine clinical trials in India. This stage mainly involves laboratory research and animal studies. Usually, it takes about 1–2 years. Key activities performed during the preclinical stage include:

Mice and monkeys are used for testing.
Researchers study immune and cellular responses.
Challenge studies evaluate protection against the actual pathogen.
Scientists determine the safest dose and best route of administration.
Developers submit laboratory data, study plans, and regulatory forms before Clinical Trials can begin.

Step 3: Submission of IND Application

After successful preclinical testing, the vaccine developer applies for permission to begin human trials in India under the vaccine approval process in India. The application is submitted to the Central Drugs Standard Control Organization (CDSCO) using Form 44, which regulates vaccine approvals under the Drugs and Cosmetics Act, 1940. Important activities carried out during this stage include:

Submission of animal study findings and toxicity data.
Preparation of detailed clinical trial protocols and study procedures.
Inclusion of available data from previous human studies, if applicable.
Submission of investigator and research site details.
Approval from the Institutional Ethics Committee (IEC) before clinical trials begin.

CDSCO reviews the application, usually within 30 days, before granting permission for Phase I–III clinical trials.

Step 4: Phase I Vaccine Clinical Trials Process

Phase I vaccine clinical trials process represent the first stage of clinical testing in humans, where a vaccine is evaluated for safety and initial immune response. This phase helps researchers understand how the body reacts to the vaccine before larger trials are conducted.

These are the key aspects of Phase I clinical trials:

Phase I trials involve a small group, a highly restricted cohort of 10-30 healthy human volunteers.
The main aim is to determine the highest safe dosage that can be tolerated without serious side effects.
Vaccine safety, tolerability, and both local and systemic adverse effects are closely monitored.
The immune response generated by the vaccine is assessed to check its effectiveness. 2

Step 5: Phase II Clinical Trials

Phase II trials are conducted after early safety has been established in humans and are designed to evaluate the vaccine in a larger group from the target population. This phase helps improve understanding of dosage, immune response, and early effectiveness.

The key features of this stage include:

Phase II Trials include several hundred participants, often from high-risk or target groups.
The optimal dose and immune response are further studied and refined.
The study design is randomized and controlled, usually with a placebo group.
Different age groups, schedules, and vaccine formulations are tested to assess performance.2

Step 6: Phase III Clinical Trials

Phase III Trials are large-scale studies conducted to confirm a vaccine’s safety, effectiveness, and optimal dosage in a diverse population over an extended period. This stage compares vaccinated and placebo groups to evaluate real-world protection.

Key aspects of Phase III clinical trials include:

Phase III Trials involve 1,000–3,000 participants from the target population, including vulnerable groups.
The study is randomized, controlled, and usually double-blinded to reduce bias.
Vaccine efficacy, immune response, tolerance, and short-term side effects are carefully assessed.
Different age groups and formulations are evaluated for consistent performance.
A critical milestone of this phase is establishing a definitive benefit versus risk ratio across diverse demographics to ensure generalizable efficacy.
After successful results, the data is submitted to regulatory authorities for detailed review before final approval.1

Step 7: Regulatory Review and Vaccine Approval

After completion of clinical trials, vaccines undergo a detailed regulatory review to ensure they are safe, effective, and of high quality before being approved for public use in India. This evaluation is carried out by the CDSCO, along with the National Regulatory Authority (NRA), expert committees, and ethics committees, following Good Clinical Practice (GCP) guidelines. All clinical and manufacturing data are carefully reviewed before final approval is granted.

The flowchart below explains the complete vaccine development and approval pathway, starting from Clinical Trials and ending with regulatory authorization for public use through the Central Licensing Approval Authority (CLAA) process.

Figure 1

The clinical trial application evaluation follows a rigorous multi-layered timeline. Once submitted to the CDSCO, the application passes to the Subject Expert Committee (SEC) within 4 weeks. Any queries raised must be addressed by the applicant within a 4-week window. The dossier then progresses through the Technical Expert Committee and the Apex Committee within 6 weeks, culminating in a final approval or No Objection Certificate (NOC) issued by the DCGI within 45 days.

During public health emergencies, this process can be compressed into less than 18 months via Emergency Use Authorization (EUA).

Step 8: Post-Marketing Surveillance and Phase IV Studies

Even after approval, vaccine monitoring continues through Phase IV studies and Pharmacovigilance programs. These post-marketing surveillance activities help identify rare adverse events, evaluate long-term safety, and monitor real-world effectiveness.

Continuous safety monitoring ensures that vaccines remain safe and effective for widespread public use.

Short Summary

Vaccine development in India begins with exploratory research where scientists identify and study suitable antigens to understand how they can trigger immune protection.
Preclinical testing is conducted in laboratories and animal models to evaluate safety and immune response and to determine appropriate dosage before human trials begin.
The clinical trials (vaccines) phases include Phase I (10 – 30 subjects), II (100 – 110 subjects), and III studies (1000 – 3000 subjects) that evaluate safety, immune response, optimal dosage, and overall vaccine effectiveness in human volunteers.

Conclusion

The vaccine clinical trials in India process ensures vaccines are safe and effective through strict scientific evaluation. From early research and preclinical testing to Phase I, II, and III human trials, each stage carefully evaluates immune response and side effects. After successful trials, CDSCO reviews the data for approval. Even after approval, continuous monitoring is done to ensure long-term safety and effectiveness in the population.

References

Ms. Srushti Ramdas Shinde, Ms. Prajkta Balakshe2. Comprehensive Review On Vaccine Regulation In India. IJRPR. 2025;6(7):270-279.
Salalli R, Dange JR, Dhiman S, Sharma T. Vaccines development in India: advances, regulation, and challenges. Clin Exp Vaccine Res. 2023;12(3):193. doi:10.7774/cevr.2023.12.3.193
Fundkar K, Gawande M. A Comprehensive Review on Regulatory Aspects of Vaccine Development and Approval Pathways Across the Globe. Computer Research And Development. 2025;25(6):137-161.