Source-This post on “Polio Vaccine” has been created based on the article “Two vaccines that brought us to the brink of eradicating polio” published in “The Hindu” on 2 July 2024.
Why in the news?
Poliovirus is now restricted to rural pockets of Afghanistan and Pakistan, is reappearing in cities due to vaccine hesitancy. The WHO’s Global Polio Eradication Initiative is expected to miss its 2024 deadline for eradication.
Key Developments in Polio Vaccine
1. Discovery of Poliovirus Growth in Non-Nerve Cells: In 1948, microbiologists John F. Enders, Thomas Weller, and Frederick Robbins found a way to grow poliovirus in non-nerve cells, which was a breakthrough that enabled mass production for vaccine research.
2. Salk’s Inactivated Polio Vaccine (IPV): Jonas Salk developed the first successful polio vaccine by inactivating the virus with formaldehyde. This vaccine induced systemic immunity by being injected into muscles.
3. Sabin’s Oral Polio Vaccine (OPV): Albert Sabin created a live, weakened vaccine administered orally. It induced strong mucosal immunity and directly target the virus’s entry point in the gut.
4. Global Impact and Strategy:
i) Countries used a combination of IPV and OPV to combat polio. OPV’s ease and superior protection were pivotal in high-incidence areas, while IPV was used when polio cases dropped to zero due to its enhanced safety.
ii) Notably, both vaccines were not patented, allowing widespread use.
5. Challenges: Despite these efforts, eradication remains elusive due to challenges like misinformation and limited access in conflict zones. Continued global cooperation and vaccination campaigns are crucial to achieving complete eradication.
Comparative Advantages and Challenges
| IPV (Inactivated Polio Vaccine) | OPV (Oral Polio Vaccine): |
| 1. Safer as it contains inactivated virus particles. 2. Induces systemic immunity, protecting blood and organ systems. 3. Requires syringes and trained personnel for administration. | 1. Easier to administer, needing no syringes or trained personnel. 2. Induces mucosal immunity, offering greater protection at the viral entry site. 3. Rarely, the weakened virus can revert and cause polio. |
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