What is Vaccine Derived Poliovirus (VDPV)?
Vaccine Derived Poliovirus (VDPV) refers to a strain of the poliovirus that has genetically mutated from the original strain contained in the oral polio vaccine (OPV). While the OPV is highly effective and safe, in rare instances, the weakened virus can mutate over time and regain virulence, leading to cases of poliovirus infection.
How Does VDPV Occur?
VDPV typically occurs when the weakened virus in the OPV is excreted by a vaccinated individual and begins to circulate in a community. Over time, especially in areas with low immunization coverage, the virus can undergo genetic changes. If it mutates enough, it can regain the ability to cause paralysis, much like the wild poliovirus.
Types of VDPV
There are three main types of VDPV:1. Circulating VDPV (cVDPV): This occurs when the excreted virus spreads within a community.
2. Immunodeficiency-related VDPV (iVDPV): Occurs in individuals with primary immunodeficiencies who are unable to clear the virus.
3. Ambiguous VDPV (aVDPV): Isolated cases where the source of the virus cannot be determined.
Why is VDPV a Concern in Pediatrics?
Children are the primary recipients of the OPV, and they are also most vulnerable to complications from poliovirus infections, including VDPV. With low immunization coverage, children are at higher risk of contracting and spreading the mutated virus, potentially leading to outbreaks of polio.
How is VDPV Diagnosed?
Diagnosis of VDPV involves collecting stool samples from the patient and testing them for poliovirus. Genetic sequencing is then performed to determine whether the virus is a vaccine-derived strain. Clinicians must also assess for symptoms such as acute flaccid paralysis, which is characteristic of poliovirus infection.
- Fever
- Fatigue
- Headache
- Vomiting
- Stiffness in the neck
- Pain in the limbs
- Acute flaccid paralysis
Prevention and Control
The primary method to prevent VDPV is maintaining high immunization coverage with the polio vaccine. The inactivated poliovirus vaccine (IPV) does not carry the risk of VDPV and is increasingly being used in many countries to mitigate this risk. Additionally, strengthening surveillance systems to quickly detect and respond to cases of poliovirus is crucial.What Should Parents Know?
Parents should be aware that the benefits of polio vaccination far outweigh the risks of VDPV. Ensuring their children are fully vaccinated according to the recommended schedule is essential for both individual and community protection. In areas where OPV is still in use, parents should understand that the vaccine is safe and that the risk of VDPV is extremely low.
Future Directions
The global health community is working towards the eradication of poliovirus. Efforts include transitioning from OPV to IPV, increasing immunization coverage, and enhancing surveillance systems. Research continues to focus on understanding the mechanisms behind VDPV and developing strategies to prevent its occurrence.Conclusion
While VDPV is a rare but serious condition, maintaining high vaccination coverage and transitioning to IPV can significantly mitigate the risk. Pediatricians play a crucial role in educating parents and ensuring children receive the necessary vaccines to protect against poliovirus and its complications.
