A recent story about the contamination of a batch of polio vaccines administered to children in Telangana and Uttar Pradesh has stirred up confusion and panic among parents. Here are the facts.
On Monday, several reports cited that a batch of oral polio vaccines manufactured by the Ghaziabad-based company Biomed was allegedly contaminated by an older strain (strain II) of the virus, which India had supposedly eradicated in 2014, as per reports by the World Health Organisation (WHO). Adding insult to injury, it was reported that a few vials from this batch of vaccines had already been administered to a few children in certain states, including Telangana.
This triggered panic and fear among the public, and not without reason.
India and its Polio-free status
In March 2014, India had been officially declared a ‘polio-free’ country, so why are these vaccines still being administered and what contamination mean? To understand the root cause, we need to delve into polio and the vaccine administered to prevent it.
Poliomyelitis or polio is a disease caused by one of three strains of the poliovirus. “There are three serotypes (or strains) of the poliovirus - PV1, PV2 and PV3,” explains Dr Udayakumar, a Chennai-based senior consultant paediatrician. “All three strains are known to be particularly infectious towards humans. The polio vaccine is developed and administered using these strains.”
The polio vaccine is of two types - the attenuated, oral polio vaccines (OPV), which are made using a weakened form of the virus, and the inactivated polio vaccines (IPV), which are developed using killed or ‘inactivated’ forms of the virus.
India’s major drive against polio began in 1978, with the Expanded Programme on Immunisation (EPI), which was an initiative against the aggressive onset of poliomyelitis in children. “Over time, this programme was altered here and there. The Universal Immunisation Programme (UIP), which we currently use to chart when and what vaccines children should be given and at what age, was launched in the 1980s and also had a huge impact on the reduction of polio rates in the country,” adds Dr Udayakumar.
Around 1995, the government introduced the Pulse Polio Campaign as a commitment towards complete polio eradication. The last known cases of polio were reported in 2011 in West Bengal and Gujarat. After a three-year monitoring period, the country received an official ‘polio-free’ status. “But we were nonetheless giving vaccinations to children, as a precautionary measure,” points out Dr Udayakumar.
However, it is important to note that after 2016, the WHO recommended that polio vaccines need not contain strain 2 of the virus, as it was eradicated globally, and that hospitals can gradually switch to bivalent vaccines. Previously, the vaccines manufactured were trivalent, which covered three strains of the virus - 1, 2 and 3.
“While we had earlier relied on the OPVs for vaccination, we now also have introduced IPV into the UIP,” explains Dr Rakesh K, a paediatrician. “The IPVs are targeted against the forms of the virus, which are currently present, 1 and 3.”
When polio strain 2 was eradicated, officials began implementing IPV into the immunisation schedule because they were found to be more effective against the only remaining two strains of the virus. However, the plan was to slowly switch from using both oral polio vaccines and inactivated polio vaccines, using only inactivated polio vaccines.
“The pulse polio programme has been extremely effective in reaching people in all regions, even remote areas, and it was cost-effective as well. So, it was an ongoing process to replace OPVs with IPVs,” explained one medical officer, working with the National Rural Health Mission.
How did these vaccines get contaminated?
Bio-med is one of few companies in the country that has been given the task of producing enough oral polio vaccines to meet the government’s needs for its campaign. After the WHO recommended bivalent vaccines, the Indian vaccine producers were told to get rid of their stock of the older form of the vaccines.
However, the recent reports seem to lead to the conclusion that the Ghaziabad-based company, Bio-med, had not paid heed to these rules. A random testing of samples indicated that 1.5 lakh vials of the vaccine may have been contaminated with strain 2 of the virus.
While it is not known exactly how these vials have been contaminated, it was reported that a random sample of OPV, tested by officials between September 12 and 14, showed evidence of adulterated vaccines.
Following a complaint registered by the Central Drugs Standard Control Organisation (CDSCO), SP Garg, managing director of Bio-med was arrested by Ghaziabad police.
It should also be noted that the CDSCO had issued a notice on March 14, against two batches of typhoid vaccines manufactured by Bio-med, and stated that the vaccines were 'not of standard quality'.
Who is at risk? What is being done?
Claims that the contaminated vaccines had been administered to children in a few states, including Telangana, drove officials into taking precautionary measures. “Most children in the state have been giving immunisation against this strain, so there is no need to panic. However, we are monitoring the situation and have issued alerts. We have also asked public health officials to be on the lookout for any alarming signs in children,” a government official said.
Additionally, after being notified by the Centre, the Telangana government has recalled the allegedly contaminated vials. “We immediately notified all districts. District medical health officers and district immunisation officers have been given instructions to recall the affected batches,” Dr Srinivasa Rao G, Telangana government’s director of public health and family welfare, told media.
The government has also stated that it would make arrangements for the bivalent, inactivated polio-virus instead of the OPVs.
While officials remain tight-lipped about the proceedings, Union Health Minister J P Nadda did allay fears and said that the government ‘would not allow poliomyelitis to come back.’
However, it also remains unclear why Bio-med was still in possession of a strain of the virus, which was supposed to have been destroyed years earlier.