The Central Drugs Standard Control Organization (CDSCO) has rejected Indian Immunologicals Ltd’s request for human trials of a six-in-one vaccine, according to two officials and documents seen by Mint. The regulator worries that an unintended leak of the polio strain could revive the crippling disease, which was banished from the country 14 years ago.
Documents reviewed by Mint showed that the IIL product uses antigens (weakened viruses) from Sinovac, China’s largest private-sector vaccine maker. Many vaccines use weakened viruses that prompt the body to create antibodies that defend against the real threat when it arrives. However, the difference here is that the Sinovac antigen uses a Chinese variant of the virus, which has never been used in any polio vaccine in India.
China’s Sinovac has sold 10 million doses of the Sabin Inactivated Poliovirus Vaccine (sIPV) across China, Thailand and Pakistan, the only three countries where it is in use.
A green light for IIL and the ensuing approvals would have paved the way for the vaccine’s commercial launch in India, where tens of millions of infants and children are administered polio vaccine every year. Rejection of the trial proposal underscores the priority placed on public health security and biosafety, even as vaccine makers push for next-generation combination shots in a vast market.
What alarmed the committee
According to documents seen by Mint, the CDSCO’s subject expert committee (SEC) for vaccines flagged potential “safety and containment issues” over the Chinese antigen. At its meeting on 22 December, the committee found IIL had not submitted ‘post-marketing surveillance’ data, including real-world safety reports from the countries where its doses were distributed. The committee noted that no study was available on this specific hexavalent vaccine containing Chinese-sourced antigens in any population.
Furthermore, Sinovac did not have approval under the WHO’s Poliovirus Containment Certification Scheme (CCS), the committee added, concluding that a “considered decision cannot be taken at this stage” for the trials to proceed. The WHO scheme provides assurance through stringent biosafety, biosecurity and oversight mechanisms.
The CDSCO reminded IIL, a subsidiary of the National Dairy Development Board (NDDB), that South-East Asia, including India, has been certified polio-free since 2014.
What Indian Immunologicals says
However, according to IIL, Sinovac is not new to India and has been selling hepatitis A vaccine in bulk to an Indian company for nearly seven years. The Sinovac tie-up for polio vaccine was based on “its superior safety profile,” managing director Dr K. Anand Kumar said in an interview.
“Unlike the Salk IPV, which is derived from a wild virus, the Sabin version uses an attenuated form of the virus that is then inactivated, making it much safer from a containment perspective. Furthermore, these are not ‘Chinese strains’ in a proprietary sense. These strains are distributed and routed through the WHO and the Netherlands Institute. In fact, the Sabin IPV manufactured by Sinovac is already a WHO pre-qualified vaccine,” Dr. Kumar said over the phone.
Lab leak fears
A ‘lab leak’ is another nightmare scenario for public health officials.
Polio viruses for research and vaccine manufacturing must be safely contained in certified ‘polio-essential facilities’, the expert committee said. It warned that ingestion is the natural route of transmission, and even fully vaccinated factory workers could become infected and shed the live virus into the community through wastewater, contaminated skin, or air.
Dr. Kumar said his company will meet all requirements.
“We have already successfully completed all pre-clinical toxicology studies and have manufactured the initial batches. While the SEC has requested specific containment certificates from Sinovac, we have already communicated this to our partners to expedite the process. We will oblige and meet all requirements set forth by the SEC,” Dr. Kumar told Mint.
Queries emailed to the spokespersons of health and family welfare as well as external affairs ministries and the DCGI on 15 January, and the Chinese embassy in New Delhi and Sinovac on 16 January remained unanswered. Queries emailed to Serum Institute, GSK and Sanofi on 15 January also weren’t answered.
What health experts think
Preventing reintroduction of the polio virus is a matter of national security, health experts said. Even though the viruses are weakened, they can “revert” to more dangerous, virulent forms, leading to outbreaks of circulating vaccine-derived polioviruses, they said.
Dr. Naveen Thacker, executive director of the International Pediatric Association (IPA), a global non-governmental professional body representing over 1 million specialists, said, “The proposal to use the Sabin strain, the same strain used in the oral polio vaccine (OPV), presents a unique challenge.” If there is an accidental lab leak during trials and the virus revives, it would become hard to preserve India’s polio-free status, Dr. Thacker said. “Conducting such trials is simply not possible without robust, WHO-certified facilities to manage the storage and handling of the materials.
He said the missing post-marketing surveillance (PMS) data was a red flag. “What happened post-marketing? That data is only from Pakistan and China; that is not enough; so, we cannot risk that,” said Dr. Thacker. “India is not currently facing a shortage that would justify taking such a risk. We have enough supply of the traditional IPV now. That was an issue a few years back, but now supply is not an issue.”
Polio has varied strains and wild polio can still exist in some countries, said Dr. Sanjeev Bagai, senior consultant, pediatrics and chairman of Nephron Clinics in New Delhi.
“Any additional strain of polio in the six-in-one vaccines must be compliant with all guidelines and regulations. The strain must have clinical real-world data validation of phased trials, which document the threshold of vaccine effectiveness. If the Chinese data is missing, then it’s best not to use that vaccine,” he said, adding there was no need for compromise in India’s infectious disease surveillance. “The worst thing is to bring in a neurotropic unverifiable strain on Indian shores.”
Pentavalent, hexavalent vaccines
Newborn babies are typically administered a single-shot pentavalent vaccine in India, which guards against five diseases – diphtheria, whooping cough, tetanus, hepatitis-B, and haemophilus influenzae type b. In addition, polio vaccines are given as oral drops.
However, companies such as Serum Institute of India, Panacea Biotec, GSK and Sanofi make and sell hexavalent vaccines, which defend against polio as well. However, hexavalent vaccines are not part of the government’s universal immunization plan. Also, none of the existing hexavalent vaccines use the Chinese antigen.
A spokesperson for Panacea Biotec, which makes EasySix, a hexavalent vaccine, said, “The SEC outcome signals India’s regulator is aligning with WHO’s Global Action Plan, making poliovirus facility certification non-negotiable. Manufacturers must demonstrate robust alignment with containment frameworks, proactively engage with National Authorities for Containment, and share broad international safety data to satisfy evolving global expectations on vaccine quality and biosafety.”
“Poliovirus Containment Certification is a non-negotiable strategic biosecurity imperative. Safeguarding India’s hard-won polio-free status requires absolute assurance that no poliovirus can escape manufacturing facilities. This certification, per WHO’s GAP-III, provides that assurance through stringent oversight, reinforcing confidence in our vaccine ecosystem,” Panacea Biotec said.
Logical step?
According to Dr. Kumar of IIL, transition is a logical step for India’s public health. “The new combination offers significant advantages for a nation with an annual birth cohort of 27 million by reducing the burden on parents and simplifying the massive logistics involved in vaccine procurement,” he said.
Although post-market surveillance data is being sought, it must be noted that the Sabin IPV program is relatively new globally, with licenses currently in China and sales in markets like Pakistan, he said.
“Ultimately, bringing more players into this space is essential for cost-competitiveness. Our program is designed to support both the private market with single-dose vials and the government’s Universal Immunization Program with multi-dose formats, should they choose to transition to hexavalent protocols,” Kumar reasoned.
