Monday June 25, 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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A One-Shot Nanoparticle Vaccine for Polio is Developed by MIT scientists

A novel single-shot nanoparticle vaccine developed by MIT researchers could assist efforts to eradicate polio worldwide. Currently, two to four polio vaccine injections are required to build up immunity, and because of the difficulty in reaching children in remote areas, the disease still prevails.

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vaccine, wikimedia

A novel single-shot nanoparticle vaccine developed by MIT researchers could assist efforts to eradicate polio worldwide.

Currently, two to four polio vaccine injections are required to build up immunity, and because of the difficulty in reaching children in remote areas, the disease still prevails.

The novel vaccine delivers multiple doses in just one injection to prevent the paralysis caused by the polio virus.

“Having a one-shot vaccine that can elicit full protection could be very valuable in being able to achieve eradication,” said Ana Jaklenec, a research scientist at MIT’s Koch Institute for Integrative Cancer Research in Cambridge, US.

“Children in some of these hard-to-reach developing world locations tend to not get the full series of shots necessary for protection. The goal is to ensure that everyone globally is immunized,” Jaklenec added, in a paper appearing in the journal Proceedings of the National Academy of Sciences.

To create a single-injection vaccine, the team encapsulated the inactivated polio vaccine in a biodegradable polymer known as PLGA.

polio
An Afghan child looks on as a health worker administers polio vaccine .

This polymer can be designed to degrade after a certain period of time, allowing the researchers to control when the vaccine is released.

The researchers designed particles that would deliver an initial burst at the time of injection, followed by a second release about 25 days later.

They injected the particles into rats, and found that the blood samples from rats immunised with the single-injection particle vaccine had an antibody response against polio virus just as strong as, or stronger than, antibodies from rats that received two injections of Salk polio vaccine — the first polio vaccine, developed in the 1950s.

Furthermore, the researchers said that they could design vaccines that deliver more than two doses, each a month apart and hope to soon be able to test the vaccines in clinical trials.

Also Read: Parents More Worried About the Vaccines Rather Than the Disease

They are also working to apply this approach to create stable, single-injection vaccines for other viruses such as Ebola and HIV. (IANS)

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