Samples of the contaminated batches were sent to the state-run Central Drugs Laboratory (CDL) Kasauli for retesting, after Bio-Med challenged the results of the initial tests by the same laboratory.
The report was submitted by CDL Kasauli to the Ghaziabad district court on 15 March. “The samples that were sent for testing following the court order were found to be positive again, which means that the batches had type 2 virus in it," two people with direct knowledge of the matter said, requesting anonymity.
The contamination endangers the health of those who have not been vaccinated for the polio-2 virus strain, according to public health expert Sylvia Karpagam. “The bigger problem is that the virus can mutate and no one knows into what form, mild or virulent," Karpagam said. “The contamination endangers many who have not received inactivated polio vaccine (IPV) and are exposed to strain 2."
An email sent to Bio-Med remained unanswered till publishing of this story.
Reports about the contamination set alarm bells in September, when traces of polio type 2 virus were found in sewage and stool samples during routine surveillance. Bio-Med was found to be supplying polio vaccines for the state-run immunization programme.
On 27 September, the Drug Controller General of India asked Bio-Med to explain how the eradicated polio-2 strain found its way into vaccine vials. Around 50,000 vials—one vial has 20 doses—of contaminated vaccine were believed to have been used in Uttar Pradesh and Telangana. The company was thereafter barred from manufacturing and supplying vaccines.
Polio drops, which carry weakened polio viruses, are given to children below five years under a government programme. The type 2 strain is thought to have been eradicated from India so long ago that the current polio vaccine no longer protects against it.
Vaccine makers were also asked to destroy their stocks of type 2 virus strain by April 2016, an order that Bio-Med has allegedly violated. Drug inspectors working to unearth the mystery behind the contamination of polio vaccines had in October also travelled to Indonesia’s PT Bio Farma Pvt. Ltd, the company that supplies the bulk vaccine called key starting material. However, they did not find anything amiss there.
That brought the spotlight back on Bio-Med, which supplied the oral vaccine for the government’s immunization programme.
PT Bio Farma said it had “proactively investigated" the matter, including batch review, facility assessment and testing of retain samples of all bulks shipped to Bio-Med using validated test methods.
“Results have shown that there have not been any discrepancies in the manufacture of these bulks. Test results of retain samples do not indicate presence of type 2 polio virus," the company said in an emailed response.