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Wednesday, October 3, 2018

Outbreak of Type 2 virus in oral polio vaccine (OPV) - India

Although the situation is not worse, its time for the regulator to revisit their enforcement strategies 

It was really moving to study about this incident in the newspapers yesterday, every parent would have experienced a relentless flow of apprehensions in their mind. Although, incidents of these magnitude are prone to occur in India it is because of the affected vulnerable group that eventually led us to dwell into the details of this incident. Let’s understand this issue in great detail


Outbreak of Type 2 virus in Oral Polio Vaccine 


Background
On September 20th 2015, the Global Commission for the Certification of Poliomyelitis Eradication (GCC) has concluded that wild poliovirus type 2 (WPV2) has been eradicated worldwide after reviewing formal documentation submitted by Member States, global poliovirus laboratory network and surveillance systems. Ironically, the last detected WPV2 dates to 1999, from Aligarh, northern India. 

What is the issue at hand?
Traces of polio type 2 virus were found in some batches of oral polio vaccine (OPV) manufactured by a Ghaziabad-based pharmaceutical company. This Polio type 2 virus strains has been eradicated worldwide, including in India. During surveillance in the northern regions of India this virus type was resurfaced. 

Which regions are these affected batches distributed?
As per the initial reports, the contaminated vaccines were majorly distributed in the immunization centers located in Uttar Pradesh, Maharashtra and Telangana. Hence, there is health alert issued for children born after April 2016

Vaccines help develop immunity by imitating an infection. This type of infection, however, almost never causes illness but it does cause the immune system to produce antibodies. Sometimes, after getting a vaccine, the imitation infection can cause minor symptoms, such as fever. Such minor symptoms are normal and should be expected as the body builds immunity. Of various types of vaccine, Live - attenuated vaccines fight viruses and bacteria. These vaccines contain a version of the living virus or bacteria which is closest to a natural infection and they act as good teachers for the immune system (by strengthening it)

What is vaccine derived Poliovirus?
A vaccine-derived polio (VDPV) is caused due to a strain of the poliovirus that are included in oral polio vaccine (OPV). Moreover, these viruses may cause illness and in rare cases paralysis. It is largely believed that Type 2 is the culprit in the vaccine induced polio (Vaccine-associated paralytic poliomyelitis (VAPP))

Why is type 2 virus banned in the oral polio vaccine (OPV)?
Post eradication reports, steps were undertaken for phased removal of type 2 virus in oral polio vaccines. Hence there is switch from using trivalent OPV (containing all three serotypes) to bivalent OPV (containing only type 1 and 3 serotypes, but not type 2) in OPV-using countries, planned for April 2016. Hence, it is not permitted to use trivalent OPV’s post May 2016

Is it time to hit the panic button?
Studies suggest that Vaccine-associated paralytic poliomyelitis (VAPP) is a rare adverse event associated with oral poliovirus vaccine (OPV). Also, the trends in VAPP vary by country income levels. As per the last available statistics by WHO, VAPP is possible in approximately 1 in 2.7 million doses of OPV and there are no reported cases till date (as on Feb 2015). Hence, the situation is not worse. Many advanced nations have already adapted alternative vaccination methods inactivated poliovirus vaccine and therefore the adverse affects of the virus are majorly from low-income nations. 

Challenges for Regulator – Does lessons learned enhance the regulatory outlook?

It is sad that, in spite of large amount being allocated in budgets annually the citizens of India are not receiving the adequate healthcare. Moreover, absence of linking children profiles (citizen identification number) during vaccination in the immunization centers would be challenging for Regulatory bodies to evaluate the gravity of this outbreak. Although, there is a process of manual data collection in these centers, it is never validated which results in weak traceability of the victims (if any). Only corrective action that can effectively implemented is to recall the affected batches of vials. As per the latest reports, the regulator arrested the one of the business owner and prosecuting. Surrounded by these constrains, it would be an uphill task for the incumbent officials to holistically address this issue. Confinement and market withdrawals are definitely one part of the corrective action; however, it would be interesting to witness the preventive measures that the Government undertakes to avoid such accidents in future. 

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Issue 23

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