Injected polio vaccine in addition to oral drops improves immunity, says study

Indian doctors warn it may be a move to bring in more expensive IPV

 
By Kundan Pandey
Last Updated: Saturday 04 July 2015

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Citing new evidence, scientists claim that giving inactivated poliovirus vaccine (IPV) to individuals who have already been administered oral poliovirus vaccine (OPV) may improve their immunity to the poliovirus.

A research paper published in the journal, Science, on Friday claims that its finding can help to resolve the controversy over vaccine choice. 

Researchers conducted a large, community-based, randomised clinical trial on nearly 1,000 infants and children in Uttar Pradesh. All subjects were given one vaccine or the other. After four weeks, all subjects, regardless of the initial dose type, got a dose of OPV.

IPV reduced viral shedding

In children who were given IPV, viral shedding was reduced, meaning that these children were much less infectious to others—a key in halting the spread of the virus.

They also found that a single dose of IPV, which is administered by injection, induced intestinal mucosal immunity more effectively in children than an additional OPV dose.

Lead author of the research and WHO’s director for polio operations and research, Hamid Jafari, suggests that  IPV should be used to accelerate the eradication of the virus in populations that have limited access to vaccination. 

Boost to global eradication drive?

Another author of the research who is assistant director-general for Polio, Emergencies and Country Collaboration with WHO, Bruce Aylward, says this study “revolutionised our understanding of IPV and how to use it in the global eradication effort to ensure children receive the best and quickest protection possible from this disease”. 

Since the development of the polio vaccine in the 1950s, efforts to eradicate the poliovirus, which can cause life-long paralysis, relied mainly on OPV—the choice of the Global Polio Eradication Initiative—rather than IPV.

In hopes of one day withdrawing OPV from treatment regimens, Jafari, Aylward and colleagues tested whether use of both vaccines would improve mucosal immunity; although administering IPV after OPV is known to close certain immunity gaps, its effect on intestinal mucosal immunity is less well-characterised.

This study was funded by the Rotary International Polio Plus Program through a grant approved by the Polio Research Committee of WHO.

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'IPV may lead to children missing vaccination'

However, Indian experts believe it as an effort to promote IPV. A Delhi based senior doctor requesting anonimity says that India has successfully controlled polio using OPV. But there is an effort to introduce IPV which would not only be costly but tough to administer as well.

There is fear that IPV will be introduced free of cost for public but gradually it would be withdrawn because of its cost. In such an event, parents would have to vaccinate their kids at their own expense. Many will miss the vaccination which may cause return of disease, they warn. 

In a letter to editor of Indian Journal of Pediatrics in 2004, visiting professor at the Centre for Social Medicine and Community Health in Jawaharlal Nehru University, C Sathyamala, and head of pediatrics department of St. Stephens Hospital in Delhi, Jacob M Puliyel, explain this with the help of Gresham’s Law. They write, “Gresham’s law states that the bad drives out the good, and that bad money drives good money out of circulation. In the context of vaccines, the equivalent law will state that if there is a more expensive vaccine alongside a cheaper vaccine (good coin of Gresham), the cheaper version will disappear from the market. (Like how the Typhoid A & B and Cholera vaccine [TABC vaccine] inexplicably disappeared, once a more expensive typhoid vaccine arrived on the scene).”

The logic is that IPV need not to be given several times like OPV. But experts say anyone cannot administer IPV; for that people will have to go to health centres and would involve, injection and pain.

 

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