April 21, 2024

Ensuring Global Protection Through IPV Vaccines

The History and Development of IPV
Polio was once one of the most feared diseases worldwide, paralysing hundreds of thousands each year. After many decades of effort, global vaccination programmes have brought the world to the brink of polio eradication. One of the key vaccines used in this fight has been the inactivated poliovirus vaccine (IPV).

IPV was developed in the 1950s by Jonas Salk as scientists sought safer alternatives to previous polio vaccines. Early versions used formaldehyde to inactivate the live poliovirus. This process killed the virus so it could no longer cause disease but still provoked an immune response. Initial trials found IPV provided good protection against the three poliovirus types that can cause paralysis.

Following licensure of IPV, mass vaccination campaigns helped dramatically reduce polio incidence in many developed nations through the mid-20th century. However, uptake remained uneven in some areas. The live oral polio vaccine (OPV) also became available in the 1960s. OPV provided gut immunity and could interrupt person-to-person transmission better than IPV. As a result, WHO recommended switching primary reliance to OPV for global polio eradication efforts from the late 1980s onwards.

Manufacturing Advances Extend IPV’s Role
While OPV remained the vaccine of choice for most polio-endemic nations, IPV production faced challenges. The process of inactivating live virus was complex and expensive. This limited IPV supply and global access for many years. However, improved cell culture methods and sterile filtration technologies in the 1980s-90s helped reduce costs and boost yields.

This revitalised interest in IPV, including for routine immunisation programs in nations no longer using OPV. Further developments now allow IPV Vaccines to be produced more affordably at scale. New combinations also pair it with other core childhood vaccines. As a result, the World Health Assembly has endorsed a long-term global policy shift back to solely using IPV after wild polio is eradicated.

Ensuring a Safe Transition Away from OPV
A key reason for this planned transition is to minimise very rare risks from OPV. In under-immunised communities, the live vaccine virus can sometimes mutate and circulate, increasing the small chance it regains ability to cause paralysis. Only two nations currently have endemic wild polio transmission, yet vaccine-derived outbreaks still occur occasionally elsewhere. Switching to IPV worldwide would eliminate this risk.

However, any change requires extensive preparation. Children who previously received OPV require follow-up IPV doses to maintain protection. countries must also ensure high vaccination rates before stopping OPV use. Transition plans are being implemented in stages, closely coordinated by WHO and partners. The final eradication of all poliovirus transmission worldwide depends on all nations safely transitioning from trivalent OPV to only using enhanced IPV schedules.

Continued Progress Towards a Polio-Free Future
Thanks to tremendous efforts, only Afghanistan and Pakistan now have endemic wild poliovirus transmission. Case numbers are also at a record low. However, continuing immunisation pressure is still needed to fully interrupt circulation. Maintaining high IPV coverage remains critical during the worldwide switch from trivalent OPV in order to protect future generations.

New presentation formats now pair IPV with other routine childhood immunisations like DTP. This makes IPV easier to deliver and improves uptake. Additional IPV doses are also recommended for high-risk communities and travelers to previously polio-affected areas. Governments, health agencies and vaccine partners continue collaborating closely on transition preparation. If strong commitment persists, global polio eradication through exclusive IPV use could be achieved within only a few more years. This would help secure a polio-free future for all children.

Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it