Polio-free India: Doubts on efficacy of single dose IPV strategy
Kalyan Ray, New Delhi: Dec 1, 2015, dhns
As India introduced the single-dose inactivated polio vaccine (IPV) shot in the national polio eradication programme, doctors doubted the strategy’s efficacy in wiping out the vaccine-derived or vaccine-associated polio infections – the two final hurdles in eradicating the disease.
Since the oral polio vaccine is made out of live but weakened virus, OPV comes with the relatively rare risk of vaccine-derived polio virus (VDPV) and vaccine-associated paralytic polio (VAPP) infections.
India witnessed 41 cases of VDPV in the last six years including two in 2014 besides close to 150 VAPP cases so far. However, there is no wild polio virus infection in India for the last three years.
While switching to IPV offers a permanent solution, three injections at the age of 6, 10 and 14 weeks are required to protect a child. A section of the medical researchers also recommend at least two shots at 6 and 14 weeks.
The union health ministry, however, launches the single dose IPV scheme for two reasons. First there is simply not enough vaccine available to cover 27 million kids and acceptance of a global time line to change the existing OPV, sources said.
“Its not proper use of IPV. What the government is doing is a stop gap manoeuvre and I am not sure of plan's success because that would depend on the extent of coverage,” Vipin Vashishth, chairman of the expert panel on immunisation at the Indian Academy of Paediatrics told Deccan Herald.
The IPV introduction was necessitated because of a global plan to switch from the trivalent OPV that offers protection against three types of polio virus to bivalent OPV by April 2016.
The crippling disease is caused by three types of viruses – type-1, type-2 and type-3. While type-2 wild virus was eliminated from India 15 years ago, the OPV used in the national programme continues to be trivalent – it imparts protection against all three types.
There is an increased risk of emergence of circulating VDPVs during the withdrawal of trivalent OPV as the immunity level against type 2 polio virus will decrease. To prevent such a risk, a single dose of IPV was recommended by the WHO.
“The two challenges for India continuing poor coverage of routine immunisation and infrequent sub-national immunisation day; and protection of young and immuno-compromised children,” argued medical researchers Manoj Grover and Nidhi Bhatnagar from NITI Aayog and Armed Forces Medical College, Pune.
In the first phase IPV will be introduced in six states - Assam, Gujarat, Punjab, Bihar, Madhya Pradesh, and Uttar Pradesh.
Since the oral polio vaccine is made out of live but weakened virus, OPV comes with the relatively rare risk of vaccine-derived polio virus (VDPV) and vaccine-associated paralytic polio (VAPP) infections.
India witnessed 41 cases of VDPV in the last six years including two in 2014 besides close to 150 VAPP cases so far. However, there is no wild polio virus infection in India for the last three years.
While switching to IPV offers a permanent solution, three injections at the age of 6, 10 and 14 weeks are required to protect a child. A section of the medical researchers also recommend at least two shots at 6 and 14 weeks.
The union health ministry, however, launches the single dose IPV scheme for two reasons. First there is simply not enough vaccine available to cover 27 million kids and acceptance of a global time line to change the existing OPV, sources said.
“Its not proper use of IPV. What the government is doing is a stop gap manoeuvre and I am not sure of plan's success because that would depend on the extent of coverage,” Vipin Vashishth, chairman of the expert panel on immunisation at the Indian Academy of Paediatrics told Deccan Herald.
The IPV introduction was necessitated because of a global plan to switch from the trivalent OPV that offers protection against three types of polio virus to bivalent OPV by April 2016.
The crippling disease is caused by three types of viruses – type-1, type-2 and type-3. While type-2 wild virus was eliminated from India 15 years ago, the OPV used in the national programme continues to be trivalent – it imparts protection against all three types.
There is an increased risk of emergence of circulating VDPVs during the withdrawal of trivalent OPV as the immunity level against type 2 polio virus will decrease. To prevent such a risk, a single dose of IPV was recommended by the WHO.
“The two challenges for India continuing poor coverage of routine immunisation and infrequent sub-national immunisation day; and protection of young and immuno-compromised children,” argued medical researchers Manoj Grover and Nidhi Bhatnagar from NITI Aayog and Armed Forces Medical College, Pune.
In the first phase IPV will be introduced in six states - Assam, Gujarat, Punjab, Bihar, Madhya Pradesh, and Uttar Pradesh.
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