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"What is Vaccine-Derived Polio?"

Context: The article discusses a case of vaccine-derived polio (VDPV) in a two-year-old child from Tikrikilla, Meghalaya. This form of polio arises not from the wild poliovirus but from a strain of poliovirus that has mutated from the oral polio vaccine (OPV).

Key Points:

1.     Vaccine-Derived Polio Virus (VDPV):

o   VDPV is a rare occurrence where the weakened virus from the OPV mutates and regains the ability to cause paralysis. This typically happens in areas with low immunization coverage, poor hygiene, and sanitation.

o   The virus circulates and mutates in under-immunized communities, potentially leading to outbreaks.

2.     Types of Polio Virus:

o   The article categorizes polioviruses into three types: wild poliovirus type 1 (WPV1), wild poliovirus type 2 (WPV2), and wild poliovirus type 3 (WPV3).

o   OPV uses a live, attenuated (weakened) virus to stimulate immunity without causing disease under normal conditions. However, in some cases, the attenuated virus can mutate and cause VDPV.

3.     Global Perspective:

o   The World Health Organization (WHO) classifies VDPVs as “circulating” (cVDPV) if they are detected in at least two sources, showing evidence of person-to-person transmission.

o   With the global shift to bivalent OPV (which contains only type 1 and type 3 polioviruses) since 2016, the risk of type 2 VDPV has increased.

4.     Prevention and Challenges:

o   Inactivated polio vaccine (IPV) is preferred because it does not carry the risk of VDPV, as it uses a killed virus. However, IPV is more expensive and requires injection.

o   The switch from trivalent OPV to bivalent OPV was an effort to reduce the risk of VDPV, yet type 2 VDPV cases have been on the rise.

Implications:

• The occurrence of VDPV highlights the need for high immunization coverage to prevent the spread of both wild and vaccine-derived polioviruses.
• The incident in Meghalaya underscores the importance of maintaining robust vaccination programs, even as polio nears global eradication, to prevent such cases.

Conclusion:

• While OPV has been instrumental in reducing polio cases worldwide, the emergence of VDPV cases poses a significant challenge to eradication efforts. The continued use of IPV and maintaining high immunization coverage are critical to preventing further outbreaks.

"NDMA to Monitor 189 High-Risk Glacial Lakes to Prevent Disasters"

Context: A two-year-old child in Tikirilla, Meghalaya, was recently diagnosed with vaccine-derived polio, a rare form of the disease that can occur in areas with low immunization coverage.

Key Points:

1.     Vaccine-Derived Poliovirus (VDPV):

o   VDPV occurs when the weakened virus in the oral polio vaccine (OPV) mutates and regains the ability to cause paralysis.

o   This can happen in areas with low vaccination coverage where the virus circulates for a prolonged period.

2.     Types of Poliovirus:

o   There are three types of poliovirus: wild poliovirus type 1 (WPV1), wild poliovirus type 2 (WPV2), and wild poliovirus type 3 (WPV3).

o   The VDPV identified in this case is classified as circulating vaccine-derived poliovirus type 2 (cVDPV2).

3.     Prevention:

o   The use of inactivated polio vaccine (IPV) is preferred in some regions due to its safety, as it does not contain live virus.

o   However, OPV is still widely used because it is easy to administer and cost-effective.

4.     Global Context:

o   The WHO has approved the use of a genetically modified type 2 novel oral polio vaccine (nOPV2) to combat cVDPV2 outbreaks.

o   The last case of wild poliovirus type 3 was eradicated in 2019.

Implications:

• The occurrence of VDPV underscores the importance of maintaining high vaccination coverage to prevent the virus from circulating and mutating. Efforts must continue to ensure global polio eradication and prevent the re-emergence of the disease.