Development of Polio Vaccines | 05 Jul 2024

Source: TH

Why in News?

The wild poliovirus is beginning to reappear in big cities in Afghanistan and Pakistan, due to vaccine hesitancy, misinformation, conflict, poverty, and limited access to these isolated regions.

• As a result, the World Health Organization's Global Polio Eradication Initiative is set to miss its deadline of eradicating polio by the end of 2026.
• The two vaccines namely Inactivated Polio Vaccine (IPV) and Oral Polio Vaccine (OPV) have helped in nearly eradicating polio from the world.

What is the History of Development of Polio Vaccines?

• The development of the 2 polio vaccines - the Inactivated Polio Vaccine (IPV) by Jonas Salk and the Oral Polio Vaccine (OPV) by Albert Sabin was a result of several key breakthroughs:
  • Culturing the Poliovirus in Non-Nerve Cells:

    • In 1948, microbiologists discovered a method to grow the poliovirus in human muscle and skin cells, rather than just in nerve cells as was previously believed.

    • This allowed for the mass production of the poliovirus, which was crucial for vaccine research and development.
  • Development of the Inactivated Polio Vaccine (IPV):

    • Jonas Salk developed the first successful polio vaccine by growing the poliovirus, inactivating it and injecting it into test subjects.

    • The IPV generated systemic immunity, as it was introduced into the muscle.

  • Development of the Oral Polio Vaccine (OPV):

    • Albert Sabin developed the OPV, which contained live, weakened poliovirus strains that were administered orally.

    • The OPV induced a powerful protective mucosal immune response in the gut, where the virus begin its infection.

What are Advantages and Disadvantages of IPV and OPV?

What are the Key Facts about Polio?

• Polio (poliomyelitis) is a highly infectious viral disease that enters the body through the mouth, multiplying in the intestine before invading the nervous system.
• It mainly affects children under 5 years of age.

  • The incubation period for poliovirus is usually 7–10 days, but it can range from 4–35 days.

• Initial symptoms of poliovirus infection include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs.
  • Up to 90% of those infected with poliovirus experience no or mild symptoms, often going unrecognised.
• One in 200 infections leads to permanent paralysis of the legs, which can occur within a few hours of infection.
  • 5-10% of those paralyzed by polio virus die when their breathing muscles become immobilised.
• The virus is shed by infected people, usually children, through faeces, and can spread quickly in areas with poor hygiene and sanitation systems.
• Cases due to wild poliovirus have decreased by over 99% since 1988, from an estimated 350 000 cases in more than 125 endemic countries, to just 2 endemic countries Afghanistan and Pakistan (as of October 2023).
• India received polio-free certification by the WHO in 2014, after three years of zero cases.

What are the Measures Taken to Eradicate Polio?

• Global:

  • Global Polio Eradication Initiative: It was launched in 1988 by  national governments and spearheaded by the WHO, Rotary International, the United States Centers for Disease Control and Prevention (CDC), and the United Nations Children's Fund (UNICEF).

  • World Polio Day: It is observed every year on 24^th October in order to call on countries to stay vigilant in their fight against the disease

• India:

  • Pulse Polio Programme:

  • Intensified Mission Indradhanush 2.0

  • Universal Immunization Programme (UIP): It was launched in 1985 with the modification to ‘Expanded Programme of Immunization (EPI). The objectives of the Programme include:

    • Rapidly increasing immunisation coverage, Improving the quality of services, Establishing a reliable cold chain system to the health facility level, Introducing a district-wise system for monitoring of performance, Achieving self-sufficiency in vaccine production.

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