Sunday September 23, 2018

India introduces injectable Inactivated Polio Vaccine

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By Nithin Sridhar

Health Minister JP Nadda launched India’s first injectable inactivated polio vaccine (IPV) on Monday. This marks the beginning of the shift from purely orally administered polio-vaccines or Oral Polio Vaccines (OPV) to a combination of dosages of OPV’s and IPV’s.

This is indeed a welcome move in the global fight against polio eradication.

One of the major disadvantages of OPV usage is that there is a chance that it leads to vaccine-associated paralytic poliomyelitis (VAPP). Studies have shown that one child out of every 2.4 million dosages of OPVs administered will suffer from VAPP.

This disadvantage can be overcome by the administration of IPV dosages. IPV was developed by Dr. Jonas Salk in 1955. IPVs consist of killed poliovirus strains (as against live attenuated polioviruses in OPVs) of all three poliovirus types which are then used as vaccines. Hence, they produce antibodies in the blood that provide immunity against all three poliovirus types resulting in protection against VAPPS as well. Further, IPVs are considered very safe and efficient and there are no major side-effects.

This is not to say that, IPVs have no disadvantage. For a long time, polio eradication programs were using OPVs alone because IPVs were observed to be weak in providing intestinal immunity. Hence, if a person immunized with IPV becomes infected with wild poliovirus, then the virus can still multiply inside the intestine and come out in the feces resulting in its continued circulation. But, a recent study shows that, when IPV is used in combination with OPV dosages, then IPVs will boost intestinal immunity.

Thus, World Health Organization (WHO) no longer recommends OPV alone vaccination against polio. It recommends usage of at least one dose of IPV in countries which is using OPV only vaccinations. In polio endemic countries, it recommends usage of 1 OPV birth dosage, 3 OPV dosages and 1 IPV dosage. In countries with high immunization cover and low chances of importation of wild polio viruses, but with a significant VAPP concern, WHO recommends an IPV–OPV sequential schedule. It recommends IPV only vaccination only in those countries which have low importation as well as transmission risks along with very high immunization coverage.

Hence, India’s move in introducing IPVs is in sync with WHO recommendations. This step will go a long way in preventing VAPP and ensuring complete polio eradication from the world.

(Photo: www.erewise.com)

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Will Polio Workers Step Out of Their Comfort Zones to End Virus?

What's more, the border between Afghanistan and Pakistan stretches for more than 2,000 kilometers. Thousands of people who cross this very porous border can easily transmit the virus in both countries.

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Polio
Widespread unrest in Afghanistan has kept thousands of children from receiving polio vaccines this year. Conflict in northern Nigeria does the same. VOA

The move to end Polio started in 1985 with Rotary International. At that time, polio paralyzed hundreds of thousands of children every year. There is still no cure, but two scientists developed vaccines against the virus in the 1950’s.

Dr. Jonas Salk produced one with an inactivated virus that could protect against polio without spreading the disease. Later, Dr. Albert Sabin developed an oral vaccine with weakened strains of the virus.

In 1988, public and private groups joined the effort in the Global Polio Eradication Program. Members included governments, the World Health Organization, the United Nations Children’s Fund (UNICEF), Rotary International, the U.S. Centers for Disease Control and Prevention (CDC) and the Bill and Melinda Gates Foundation.

Since then, the number of polio cases has dropped by 99.9 percent. Last year, 22 children were crippled by this disease. The wild polio virus exists in only three countries: Pakistan, Afghanistan and Nigeria, but it’s still a global threat.

Dr. John Vertefeuille, from the CDC said, “This last mile is a complicated mile.” It’s not just because of conflict or terrorism. “It’s extreme remoteness. It’s very fragile health systems.” And in these remote conflict prone areas gaining access to children can be a major problem.

If polio exists anywhere, it can once again spread everywhere.

Polio
In many places the vaccinators are women because women can go into the homes, talk to other women and gain access to the children. Wikimedia

Vertefeuille and other experts discussed strategies to realize a polio-free world July 10 at the Center for Strategic and International Studies in Washington.

Widespread unrest in Afghanistan has kept thousands of children from receiving polio vaccines this year. Conflict in northern Nigeria does the same.

What’s more, the border between Afghanistan and Pakistan stretches for more than 2,000 kilometers. Thousands of people who cross this very porous border can easily transmit the virus in both countries.

While the funding and technical support has to come from large, private-public partnerships, immunization teams succeed best if they are local. Approaches have to take culture and customs into consideration.

In many places the vaccinators are women because women can go into the homes, talk to other women and gain access to the children.

Elsewhere, soldiers vaccinate children when they take over an area run by anti-government forces. Vaccination teams have to be prepared to move quickly when there is a lull in the fighting and to deliver multiple doses of vaccine in a short period of time.

Polio
Community volunteers are a great resource. Some get cell phones so they can alert health officials if a child becomes paralyzed. VOA

Surveillance is just as critical. To end polio, you have to know where the outbreaks are. Community volunteers are a great resource. Some get cell phones so they can alert health officials if a child becomes paralyzed.

Another challenge is getting children in migrant groups vaccinated. Vertefeuille says this is where technology helps. The CDC uses satellites to see where people have moved and what areas are abandoned. Clues are where structures have been repaired, where the grass grows on roads, indicating abandoned areas, and where it doesn’t, indicating where people are living.

Dr. Andrew Etsana from the International Federation of Red Cross and Red Crescent Societies said these groups present a particular challenge because “you have people moving with a virus and it is difficult to track them and vaccinate the vulnerable children in this mobile population.”

Another issue is the nature of viruses themselves. Viruses mutate. So far, the polio vaccines have been effective, but if not enough children get vaccinated, the virus can change, and perhaps make the vaccine less effective. That’s why every child needs to be vaccinated.

Outbreaks that can be avoided by vaccinating the whole population so that there are no gaps for the mutated virus to slip through.

International experts are working with local leaders to close this gap.

Another issue is complacency. Etsana said, “People are getting tired. The program has been going on. They thought it would have ended.”

Rotary has pledged to continue its support, other groups as well. International support and funding is critical to ending polio, but after three decades, many people have never seen polio. Etsana says he sees complacency creeping into all areas of the program. “The funders of the program are also getting tired. The fund is drying up and if the fund dries up and the job is not done, we’re going to have a major problem. We may have reinfection.”

Also Read-After Three Years Struggle, WHO Declares Somalia Polio Free

But, if people recognize the program’s value – it has united communities, established vaccine centers, created partnerships never before imagined – the world can not only end polio, but tackle other diseases as well. The polio program is widely credited with stopping the spread of Ebola in Nigeria while the disease ravaged other west African countries. (VOA)